Patent Publication Number: US-2019170952-A1

Title: Optical module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-232321, filed on Dec. 4, 2017, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to an optical module. 
     BACKGROUND 
     In the related art, there is an optical module that includes, for example, multiple light sources such as laser diodes arranged in parallel in the form of an array, and lenses corresponding to the respective light sources. In addition, there has been known a lens unit which includes a lens array in which multiple pairs of lenses, each of which includes a first lens for forming a contracted inverted image of an object and a second lens for forming an expanded inverted image of the image formed by the first lens, are arranged in a substantially linear shape (see, e.g., Japanese Laid-open Patent Publication No. 2012-189915). 
     Related techniques are disclosed in, for example, Japanese Laid-open Patent Publication No. 2012-189915. 
     SUMMARY 
     According to an aspect of the embodiments, an optical module includes a first light source configured to emit a first light beam, a second light source configured to emit a second light beam, and a lens member configured to include a first lens configured to transmit the first light beam, a second lens provided adjacent to the first lens and configured to transmit the second light beam, and a gap provided between the first lens and the second lens. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view illustrating an example of a microlens according to a first embodiment; 
         FIG. 2  is a top plan view illustrating an example of the microlens according to the first embodiment; 
         FIG. 3  is a bottom view illustrating another example of the microlens according to the first embodiment; 
         FIG. 4  is a top plan view illustrating another example of the microlens according to the first embodiment; 
         FIG. 5  is a cross-sectional view illustrating another example of the microlens according to the first embodiment; 
         FIG. 6  is a cross-sectional view illustrating an example of an optical module according to the first embodiment; 
         FIG. 7  is a cross-sectional view illustrating an example of a part of the optical module according to the first embodiment; 
         FIG. 8  is a front view illustrating an example of a microlens according to a second embodiment; 
         FIG. 9  is a top plan view illustrating an example of the microlens according to the second embodiment; 
         FIG. 10  is a bottom view illustrating another example of the microlens according to the second embodiment; 
         FIG. 11  is a top plan view illustrating another example of the microlens according to the second embodiment; 
         FIG. 12  is a cross-sectional view illustrating another example of the microlens according to the second embodiment; 
         FIG. 13  is a front view illustrating an example of a microlens according to a third embodiment; 
         FIG. 14  is a top plan view illustrating an example of the microlens according to the third embodiment; and 
         FIG. 15  is a bottom view illustrating another example of the microlens according to the third embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the related art, an oblique light beam incident to a lens leaks to a neighboring lens in some cases. If the light leaks to the neighboring lens, for example, quality of an optical signal deteriorates. 
     Hereinafter, embodiments of a technology capable of suppressing an oblique light beam incident to a lens from leaking to a neighboring lens will be described in detail with reference to the drawings. 
     First Embodiment 
     Example of Microlens According to First Embodiment 
       FIG. 1  is a front view illustrating an example of a microlens according to a first embodiment.  FIG. 2  is a top plan view illustrating an example of the microlens according to the first embodiment. A microlens  100  according to the first embodiment illustrating  FIGS. 1 and 2  is an example of a lens member included in an optical module according to the first embodiment. For example, light emitted from a light source included in the optical module according to the first embodiment, is incident to the microlens  100 . The optical module according to the first embodiment will be described below (see, e.g.,  FIGS. 6 and 7 ). 
     The microlens  100  is a one-piece lens member. The one-piece lens member is a single member having a portion that acts as a lens. As illustrated in  FIGS. 1 and 2 , the microlens  100  has, for example, lens units  111  to  116  arranged in the form of an array. Each of the lens units  111  to  116  is a part of the microlens  100  and acts as a lens. 
     For example, the lens unit  111  is a lens unit that corresponds to a VCSEL  151  and an optical fiber  161 . The VCSEL  151  emits a laser beam  171   a  to the lens unit  111 . VCSEL stands for Vertical Cavity Surface Emitting Laser. For example, the laser beam  171   a  is an optical signal to be transmitted by the optical fiber  161 . The laser beam  171   a  emitted from the VCSEL  151  is incident to the lens unit  111  from a convex lens portion  111   a  formed at a portion of the lens unit  111  adjacent to the VCSEL  151 . The lens unit  111  emits the laser beam, which has been incident to the lens unit  111 , to the optical fiber  161  from a convex lens portion  111   b  formed at a portion of the lens unit  111  adjacent to the optical fiber  161 . For example, the laser beam, which has been incident to the lens unit  111  from the convex lens portion  111   a , is transmitted through an intermediate portion  111   c  between the convex lens portion  111   a  and the convex lens portion  111   b  and then emitted from the convex lens portion  111   b . A laser beam  171   b , which has been emitted from the convex lens portion  111   b , is incident to the optical fiber  161 . The optical fiber  161  transmits the laser beam, which has been incident to the optical fiber  161 , to a corresponding device of the optical module according to the first embodiment. 
     For example, the lens unit  112  is a lens unit that corresponds to a VCSEL  152  and an optical fiber  162 . The VCSEL  152  emits a laser beam  172   a  to the lens unit  112 . For example, the laser beam  172   a  is an optical signal to be transmitted by the optical fiber  162 . The laser beam  172   a  emitted from the VCSEL  152  is incident to the lens unit  112  from a convex lens unit  112   a  formed at a portion of the lens unit  112  adjacent to the VCSEL  152 . The lens unit  112  emits the laser beam, which has been incident to the lens unit  112 , to the optical fiber  162  from a convex lens portion  112   b  formed at a portion of the lens unit  112  adjacent to the optical fiber  162 . For example, the laser beam, which has been incident to the lens unit  112  from the convex lens portion  112   a , is transmitted through an intermediate portion  112   c  between the convex lens portion  112   a  and the convex lens portion  112   b  and then emitted from the convex lens portion  112   b . A laser beam  172   b , which has been emitted from the convex lens portion  112   b , is incident to the optical fiber  162 . The optical fiber  162  transmits the laser beam, which has been incident to the optical fiber  161 , to the corresponding device of the optical module according to the first embodiment. 
     Similarly, the lens units  113  to  116  are lens units that correspond to VCSELs  153  to  156  and optical fibers  163  to  166 , respectively. The VCSELs  153  to  156  emit laser beams  173   a  to  176   a  to the lens units  113  to  116 , respectively. The laser beams  173   a  to  176   a  are optical signals to be transmitted by the optical fibers  163  to  166 , respectively. The laser beams  173   a  to  176   a , which have been emitted from the VCSELs  153  to  156 , respectively, are incident to the lens units  113  to  116  from convex lens portions  113   a  to  116   a , respectively. The lens units  113  to  116  emit the laser beams, which have been incident to the lens units  113  to  116 , respectively, to the optical fibers  163  to  166  from convex lens portions  113   b  to  116   b , respectively. For example, the laser beams, which have been incident to the lens units  113  to  116  from the convex lens portions  113   a  to  116   a , respectively, are transmitted through intermediate portions between the convex lens portions  113   a  to  116   a  and the convex lens portions  113   b  to  116   b  and then emitted from the convex lens portions  113   b  to  116   b , respectively. The laser beams  173   b  to  176   b , which have been emitted from the convex lens portions  113   b  to  116   b , respectively, are incident to the optical fibers  163  to  166 , respectively. The optical fibers  163  to  166  transmit the laser beams, which have been incident to the optical fibers  163  to  166 , respectively, to the corresponding device of the optical module according to the first embodiment. 
     The VCSELs  151  to  156  are examples of the light sources included in the optical module according to the first embodiment. In addition, the optical fibers  161  to  166  are examples of optical transmission paths provided in the optical module according to the first embodiment. 
     Because the lens units  111  to  116  are made of, for example, resin or glass, a refractive index (absolute refractive index) of each of the lens units  111  to  116  is greater than 1. An example of the refractive index of each of the lens units  111  to  116  is 1.5. In addition, an example of a pitch of each of the lens units  111  to  116  is 250 μm. The pitch of each of the lens units  111  to  116  is, for example, a distance between centers of the convex lens portions of the adjacent lens units, that is, a pitch of the arrangement of the respective lens units. In addition, an example of a diameter of each of the lens units  111  to  116  is 250 μm. In addition, the pitch of each of the lens units  111  to  116  may be greater than, for example, 250 μm in order to provide connecting units  121   a  to  121   e  and  122   a  to  122   e  and gaps  131   a  to  131   e  to be described below. 
     Each of the connecting unit  121   a  to  121   e  and  122   a  to  122   e  and each of the gaps  131   a  to  131   e  are provided between the adjacent lens units among the lens units  111  to  116  of the microlens  100 . Each of the connecting units  121   a  to  121   e  and  122   a  to  122   e  is a portion that connects the adjacent lens units among the lens units  111  to  116 . Here, the connection means the physical connection. The physical connection means, for example, that there is no gap. Since there is the portion that connects the adjacent lens units, the adjacent lens units are fixed to each other by the portion. For example, the connecting units  121   a  and  122   a  between the lens unit  111  and the lens unit  112  are portions that connect the lens unit  111  and the lens unit  112 . The connecting units  121   a  to  121   e  and  122   a  to  122   e  may maintain a predetermined pitch of the lens units  111  to  116  and the state where the lens units  111  to  116  are disposed in parallel with one another. 
     For example, as described below, the VCSELs  151  to  155  are provided on a board included in the optical module according to the first embodiment. In the following description, the board included in the optical module according to the first embodiment is simply referred to as a “board” in some cases. 
     The VCSELs  151  to  155  are provided on the board to have the same pitch as the lens units  111  to  115 . For example, it is assumed that the lens units  111  to  115  are provided to have a pitch of 250 μm. In this case, the VCSELs  151  to  155  are also provided to have a pitch of 250 μm. That is, the pitch of the VCSELs  151  to  155  is 250 μm. The pitch of the VCSELs  151  to  155  is, for example, a distance between centers of laser beam emitting ports of the adjacent VCSELs, that is, a pitch of the arrangement of the respective VCSELs. 
     For example, when manufacturing the optical module, a manufacturer of the optical module according to the first embodiment positions the microlens  100  so that the laser beams  171   a  to  175   a  emitted from the VCSELs  151  to  155  are incident to the lens units  111  to  115 , respectively. At the time of the positioning, when the lens unit  111  and the VCSEL  151  are positioned, for example, the lens units  112  to  115  and the VCSELs  152  to  155  are also positioned because of the connecting units  121   a  to  121   e  and  122   a  to  122   e . For this reason, according to the microlens  100 , it is not necessary to individually position the lens units  111  to  115  and the VCSELs  151  to  155 , and as a result, it is possible to reduce the number of positioning processes. 
     Each of the gaps  131   a  to  131   e  is a portion between the adjacent lens units among the lens units  111  to  116 , that is, a portion where the adjacent lens units are disconnected from each other. Here, the disconnection means the physical disconnection. The physical disconnection means, for example, that the adjacent lens units are spaced apart from each other. For example, the gap  131   a  between the lens unit  111  and the lens unit  112  is a portion where the lens unit  111  and the lens unit  112  are disconnected from each other. In addition, each of the gaps  131   a  to  131   e  is provided, for example, between the intermediate portions of the adjusted lens units. For example, as illustrated in  FIG. 1 , the gap  131   a  between the lens unit  111  and the lens unit  112  is provided between the intermediate portion  111   c  and the intermediate portion  112   c . In addition, the gaps  131   a  to  131   e  are filled with, for example, air. In this case, a refractive index (absolute refractive index) of each of the gaps  131   a  to  131   e  is about 1 and smaller than the refractive index of each of the lens units  111  to  116 . 
     Therefore, for example, in a case where an oblique light beam, which is oblique with respect to an optical axis of the lens unit  111 , is incident to the lens unit  111  and then the oblique light beam reaches a boundary surface between the lens unit  111  and the gap  131   a , the oblique light beam is totally reflected toward the lens unit  111  by the boundary surface between the lens unit  111  and the gap  131   a . The optical axis is a virtual light ray that represents the light beam passing through an entire optical system. For example, the optical axis is a straight line (main axis) that passes through the center of the lens and is perpendicular to a lens surface. For example, the gap  131   a  is provided in parallel with the optical axis of the lens unit  111 . For example, the optical axis of the lens unit  111  is a straight line that passes through the center of the convex lens portion  111   a  and the center of the convex lens portion  111   b . Since the gap  131   a  is provided in parallel with the optical axis of the lens unit  111 , when the oblique light beam, which has been incident to the lens unit  111  from a light incidence side of the lens unit  111 , reaches the boundary surface between the lens unit  111  and the gap  131   a , the oblique light beam is, for example, totally reflected to a light emission side of the lens unit  111 . 
     Similarly, it is assumed that the oblique light beams, which are oblique with respect to the optical axes of the lens units  112  to  116 , respectively, are incident to the lens units  112  to  116  and then the oblique light beams reach the boundary surfaces between the lens units  112  to  116  and the gaps  131   b  to  131   e . In this case, the oblique light beams are totally reflected toward the lens units  112  to  116  by the boundary surfaces between the lens units  112  to  116  and the gaps  131   b  to  131   e . In addition, for example, the gaps  131   b  to  131   e  are provided in parallel with the optical axes of the lens units  112  to  116 , respectively. The optical axes of the lens units  112  to  116  are straight lines that pass through the centers of the convex lens portions  112   a  to  116   a  and the centers of the convex lens portions  111   b  to  116   b , respectively. Since the gaps  131   b  to  131   e  are provided in parallel with the optical axes of the lens units  112  to  116 , when the oblique light beams, which have been incident from the light incidence sides of the lens units  112  to  116 , reach the boundary surfaces with the gaps  131   b  to  131   e , the oblique light beams are totally reflected toward the light emission sides of the lens units  112  to  116 . 
     The gaps  131   a  to  131   e  may be filled with gas other than air, or may be in a vacuum state. As the refractive index of each of the gaps  131   a  to  131   e  decreases, a difference between the refractive index of each of the lens units  111  to  116  and the refractive index of each of the gaps  131   a  to  131   e  may increase. Therefore, by decreasing the refractive index of each of the gaps  131   a  to  131   e , it is possible to decrease a critical angle set for totally reflecting the oblique light beam, which has been incident to each of the lens units  111  to  116 , by the boundary surface with each of the gaps  131   a  to  131   e . For this reason, by decreasing the refractive index of each of the gaps  131   a  to  131   e , it is easy to totally reflect the oblique light beam, which has been incident to each of the lens units  111  to  116 , by the boundary surface between each of the lens units  111  to  116  and each of the gaps  131   a  to  131   e . The gaps  131   a  to  131   e  are examples of slits which are parallel to the optical axes of the lens units  111  to  116 , respectively. 
     For example, the microlens  100  may be implemented by integrally forming the lens units  111  to  116  and the connecting units  121   a  to  121   e  and  122   a  to  122   e  by using a mold or the like and by using resin or glass. Therefore, it is possible to easily form the microlens  100  that has the lens units  111  to  116  in which the directions of the optical axes and the pitch are constant, and the connecting units  121   a  to  121   e  and  122   a  to  122   e  and the gaps  131   a  to  131   e.    
     In the optical module having the microlens  100  and the VCSELs  151  to  156 , the VCSEL  151  may be provided in a state deviating from a regular state. For example, as illustrated in  FIG. 1 , the VCSEL  151  may be provided obliquely with respect to the lens unit  111  without facing the convex lens portion  111   a.    
     In the case where the VCSEL  151  is provided obliquely with respect to the lens unit  111 , a center of the laser beam  171   a , which is emitted from the VCSEL  151 , is also oblique with respect to the optical axis of the lens unit  111 , as illustrated in  FIG. 1 . As a result, the oblique light beam is incident to the lens unit  111 . Further, in this case, an optical path of the oblique light beam, which has been incident to the lens unit  111 , is, for example, an optical path indicated by the arrow  181 . That is, in this case, the oblique light beam, which has been incident to the lens unit  111 , travels in the lens unit  111  first, for example, to a point P 1  which is a part of the boundary surface between the lens unit  111  and the gap  131   a . Further, the oblique light beam, which has reached the point P 1 , is totally reflected at the point P 1  toward the lens unit  111 , travels in the lens unit  111  again, and then is emitted, as the laser beam  171   b , from the convex lens portion  111   b  to the optical fiber  161 . 
     Therefore, according to the microlens  100 , since the oblique light beam, which has been incident to the lens unit  111 , is totally reflected when the oblique light beam reaches the gap  131   a , it is possible to suppress the oblique light beam, which has been incident to the lens unit  111 , from leaking to the neighboring lens unit  112 . For this reason, according to the microlens  100 , it is possible to reduce crosstalk occurring when the oblique light beam, which has been incident to the lens unit  111 , leaks to the lens unit  112 , and thus it is possible to reduce deterioration in the optical signal caused by the crosstalk. 
     Similarly, in the optical module having the microlens  100  and the VCSELs  151  to  156 , the VCSEL  152  may be provided in a state deviating from a regular state. For example, as illustrated in  FIG. 1 , the VCSEL  152  may be provided obliquely with respect to the lens unit  112  without facing the convex lens portion  112   a.    
     In the case where the VCSEL  152  is provided obliquely with respect to the lens unit  112 , a center of the laser beam  172   a , which is emitted from the VCSEL  152 , is also oblique with respect to the optical axis of the lens unit  112 , as illustrated in  FIG. 1 . As a result, the oblique light beam is incident to the lens unit  112 . Further, in this case, an optical path of the oblique light beam, which has been incident to the lens unit  112 , is, for example, an optical path indicated by the arrow  182 . That is, in this case, the oblique light beam, which has been incident to the lens unit  112 , travels in the lens unit  112  first, for example, to a point P 2  which is a part of the boundary surface between the lens unit  112  and the gap  131   a . Further, the oblique light beam, which has reached the point P 2 , is totally reflected at the point P 2  toward the lens unit  112 , travels in the lens unit  112  again, and then is emitted, as the laser beam  172   b , from the convex lens portion  112   b  to the optical fiber  162 . 
     Therefore, according to the microlens  100 , since the oblique light beam, which has been incident to the lens unit  112 , is totally reflected when the oblique light beam reaches the gap  131   a , it is possible to suppress the oblique light beam, which has been incident to the lens unit  112 , from leaking to the neighboring lens unit  111 . For this reason, according to the microlens  100 , it is possible to reduce crosstalk occurring when the oblique light beam, which has been incident to the lens unit  112 , leaks to the lens unit  111 , and thus it is possible to reduce deterioration in the optical signal caused by the crosstalk. 
     A simulation in terms of the amount of crosstalk occurring when the laser beam of the VCSEL  151  leaks to the lens unit  112  was performed on the microlens  100  illustrated in  FIG. 1  in respect to a case where the gap  131   a  is provided and a case where no gap  131   a  is provided. As a result of the simulation, the amount of crosstalk was 0 dBm in the case where the gap  131   a  was provided, and the amount of crosstalk was 3.653e−8 dBm in the case where no gap  131   a  was provided. Here, e−8 means 10 to the power of −8. In addition, the simulations were performed under a condition in which it was assumed that the VCSEL  151  was provided to face the lens unit  111 . It is conceivable that a difference in amount of crosstalk between the presence and the absence of the gap  131   a  becomes greater when it is assumed that the VCSEL  151  is provided in the state deviating from the regular state, as illustrated in  FIG. 1 . 
     In the example described above, the VCSELs  151  to  156  are provided as the light sources corresponding to the microlens  100 , but the light sources corresponding to the microlens  100  are not limited to the VCSELs  151  to  156 . For example, as illustrated in  FIG. 1 , a PD  191  may be provided instead of the VCSEL  151 . PD stands for photodiode. In the case where the PD  191  is provided, the optical fiber  161 , for example, outputs the laser beam, which has been incident to the optical fiber  161  from the corresponding device of the optical module according to the first embodiment, to the lens unit  111 . The laser beam, which has been emitted from the optical fiber  161 , is incident to the lens unit  111  from the convex lens portion  111   b . Further, the lens unit  111  outputs the laser beam, which has been incident to the lens unit  111 , to the PD  191  from the convex lens portion  111   a . The PD  191  receives the light incident to the PD  191 . 
     In the case where the PD  191  is provided, the corresponding device of the optical module according to the first embodiment may receive the laser beam obliquely with respect to the optical fiber  161 , or an angle deviation may occur in the optical fiber  161 . In this case, the center of the laser beam emitted from the optical fiber  161  is oblique with respect to the optical axis of the lens unit  111 . As a result, the oblique light beam may be incident to the lens unit  111 , and the oblique light beam, which has been incident to the lens unit  111 , may reach the boundary surface between the lens unit  111  and the gap  131   a . Even in this case, according to the microlens  100 , the oblique light beam, which has reached the boundary surface between the lens unit  111  and the gap  131   a , may be totally reflected toward the lens unit  111  by the boundary surface between the lens unit  111  and the gap  131   a.    
     Therefore, according to the microlens  100 , even in the case where the PD  191  is provided, it is possible to suppress the oblique light beam, which has been incident to the lens unit  111 , from leaking to the neighboring lens unit  112 . For this reason, according to the microlens  100 , it is possible to reduce crosstalk when the oblique light beam, which has been incident to the lens unit  111 , leaks to the neighboring lens unit  112 , and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     Similarly, PDs  192  to  196  may be provided instead of the VCSELs  152  to  156 . In the case where the PDs  192  to  196  are provided, the optical fibers  162  to  166 , for example, output the laser beams, which have been incident to the optical fibers  162  to  166  from the corresponding device of the optical module according to the first embodiment, to the lens units  112  to  116 . The laser beams, which have been emitted from the optical fibers  162  to  166 , are incident to the lens units  112  to  116  from the convex lens portions  112   b  to  116   b . Further, the lens units  112  to  116  output the laser beams, which have been incident to the lens units  112  to  116 , to the PDs  192  to  196  from the convex lens portions  112   a  to  116   a . The PDs  192  to  196  receive the light incident to the PDs  192  to  196 . 
     Even in the case where the PDs  192  to  196  are provided, the centers of the laser beams emitted from the optical fibers  162  to  166  may tilt with respect to the optical axes of the lens units  112  to  116 , so that oblique light beams may be incident to the lens units  112  to  116 . Even in this case, according to the microlens  100 , the oblique light beams, which have reached the boundary surfaces between the lens units  112  to  116  and the gaps  131   b  to  131   e , may be totally reflected toward the lens units  112  to  116  by the boundary surfaces between the lens units  112  to  116  and the gaps  131   b  to  131   e.    
     Therefore, according to the microlens  100 , even in the case where the PDs  192  to  196  are provided, it is possible to suppress the oblique light beams, which have been incident to the lens units  112  to  116 , from leaking to the neighboring lens units. For this reason, according to the microlens  100 , it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  112  to  116 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by the crosstalk. The PDs  191  to  196  are examples of the light sources included in the optical module according to the first embodiment. 
     In the above description, the example in which the six lens units, that is, the lens units  111  to  116  are provided in the microlens  100  has been described, but the number of lens units is not limited thereto. For example, in the microlens  100 , two to five lens units (e.g., only the two lens units  111  and  112 ) may be provided, or seven or more lens units may be provided. 
     In the example described above, the adjacent lens units among the lens units  111  to  116  are physically connected to each other by the two connecting units, but the connection is not limited thereto. For example, the adjacent lens units among the lens units  111  to  116  may be physically connected to each other by a single connecting unit. For example, in this case, the lens unit  111  and the lens unit  112  is physically connected to each other only by the connecting unit  121   a , and a side below the connecting unit  121   a  between the lens unit  111  and the lens unit  112  in  FIG. 1  is entirely formed as the gap  131   a . In this way, it is possible to suppress the oblique light beams, which have been incident to the lens units  111  to  116 , from leaking to the neighboring lens units through the connecting units. For this reason, it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  112  to  116 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by the crosstalk. In addition, in this way, only the connecting units  121   a  to  121   e , which are closer to the light incidence sides than the light emission sides of the lens units  111  to  116 , are provided, and as a result, it is possible to suppress the oblique light beams, which have been incident to the lens units  111  to  116 , from leaking to the neighboring lens units through the connecting units  121   a  to  121   e . For this reason, it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  112  to  116 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     The adjacent lens units among the lens units  111  to  116  may be physically connected to each other by three or more connecting units. For example, in this case, the lens unit  111  and the lens unit  112  are physically connected to each other by the connecting units  121   a  and  122   a  and another connecting unit, and the gaps  131   a  are provided between the respective connecting units. In this way, it is possible to increase strength by which the adjacent lens units among the lens units  111  to  116  are connected to each other. 
     In the example described above, for example, the connecting units  122   a  to  122   e  are provided at the positions close to the convex lens portions  111   b  to  116   b  of the lens units  111  to  116  from which the laser beams  171   b  to  176   b  are emitted, but the positions of the connecting units  122   a  to  122   e  are not limited thereto. For example, similar to the connecting units  121   a  to  121   e , the connecting units  122   a  to  122   e  may also be provided at the positions closer to the convex lens portions  111   a  to  116   a  of the lens units  111  to  116 , from which the laser beams  171   a  to  176   a  enter, than the convex lens portions  111   b  to  116   b . Since the connecting units  121   a  to  121   e  and  122   a  to  122   e  are provided at the positions closer to the light incidence sides than the light emission sides of the lens units  111  to  116 , it is possible to suppress the oblique light beams, which have been incident to the lens units  111  to  116 , from leaking to the neighboring lens units through the connecting units  121   a  to  121   e  and  122   a  to  122   e . For this reason, it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  112  to  116 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     Another Example of Microlens According to First Embodiment 
     Another example of the microlens  100  according to the first embodiment to be described below is an example in which an optical path changing unit, which changes a traveling direction of the light which has been incident to the microlens  100 , is provided in the microlens  100 . 
       FIG. 3  is a bottom view illustrating another example of the microlens according to the first embodiment.  FIG. 4  is a top plan view illustrating another example of the microlens according to the first embodiment. In  FIGS. 3 and 4 , constituent elements identical to the constituent elements in  FIG. 1  are denoted by the same reference numerals, and descriptions thereof will be omitted. 
     The microlens  100  illustrated in  FIGS. 3 and 4  has the lens units  111  to  115 . In addition, the microlens  100  is formed in the form of a block having a lower surface  301  (see  FIG. 3 ), a lateral surface  302  (see  FIG. 3 ), and an upper surface  303  (see  FIG. 4 ). The convex lens portions  111   a  to  115   a  of the lens units  111  to  115  protrude, for example, from the lower surface  301 . That is, the lower surface  301  of the microlens  100  is, for example, provided to face the VCSELs  151  to  155 . 
     The lateral surface  302  is, for example, provided to be perpendicular to the lower surface  301 . The convex lens portions  111   b  to  115   b  of the lens units  111  to  115  protrude, for example, from the lateral surface  302 . That is, the lateral surface  302  of the microlens  100  is, for example, provided to face the optical fibers  161  to  165 . In addition, the upper surface  303  is, for example, provided to be inclined at 45 degrees with respect to each of the lower surface  301  and the lateral surface  302 . 
       FIG. 5  is a cross-sectional view illustrating another example of the microlens according to the first embodiment. For example,  FIG. 5  illustrates an example of a cross section of the microlens  100  illustrated in  FIGS. 3 and 4  taken along line A-A in  FIG. 4  when viewed in a direction from the bottom to the top in  FIG. 4 . 
     As illustrated in  FIG. 5 , a portion of the upper surface  303 , which corresponds to the convex lens portion  111   a  and the convex lens portion  111   b , is an optical path changing unit  500 . The optical path changing unit  500  is inclined at 45 degrees with respect to each of an optical axis of the convex lens portion  111   a  and an optical axis of the convex lens portion  112   a . In addition, the outside of the microlens  100  is, for example, air. For this reason, a refractive index outside the microlens  100  is about 1 and smaller than the refractive index of the lens unit  111 . Therefore, for example, the laser beam, which has been incident to the lens unit  111  from the convex lens portion  111   a , is totally reflected toward the convex lens portion  111   b  by a boundary surface between the lens unit  111  and the optical path changing unit  500 . For this reason, a traveling direction of the laser beam, which has been incident to the lens unit  111  from the convex lens portion  111   a , is changed by 90 degrees toward the convex lens portion  111   b , as indicated by the arrow  510 , and the laser beam is emitted from the convex lens portion  111   b.    
     Although not illustrated, similarly, optical path changing units are also provided by the upper surface  303  at portions of the upper surface  303  which corresponds to the convex lens portions  112   a  to  115   a  and the convex lens portions  112   b  to  115   b . Therefore, for example, the laser beams, which have been incident to the lens units  112  to  115  from the convex lens portions  112   b  to  115   b , are totally reflected toward the convex lens portions  112   b  to  115   b  by the boundary surfaces between the lens units  112  to  115  and the optical path changing units. For this reason, traveling directions of the laser beams, which have been incident to the lens units  112  to  115  from the convex lens portions  112   a  to  115   a , are changed by 90 degrees toward the convex lens portions  112   b  to  115   b , and the laser beams are emitted from the convex lens portions  112   b  to  115   b.    
     In the microlens  100  illustrated in  FIGS. 3 to 5 , the gap  131   a  between the lens unit  111  and the lens unit  112  is provided such that the laser beam, which has been incident from the convex lens portion  111   a , travels along at least a part of the optical path along which the laser beam travels until the laser beam is emitted from the convex lens portion  111   b . For example, in the microlens  100  illustrated in  FIGS. 3 to 5 , the gap  131   a  between the lens unit  111  and the lens unit  112  is provided at a position indicated by a virtual line  520 . In addition, the gap  131   a  between the lens unit  111  and the lens unit  112  is not limited thereto and may be provided at a position indicated by a virtual line  530 , for example, in consideration of ease of forming using a mold. 
     In the microlens  100  illustrated in  FIGS. 3 to 5 , the optical axis of the lens unit  111  coincides with the arrow  510 , for example. In the microlens  100  illustrated in  FIGS. 3 to 5 , the gap  131   a  between the lens unit  111  and the lens unit  112  may be provided in parallel with the optical axis of the lens unit  111  which coincides with the arrow  510 . 
     In the microlens  100  illustrated in  FIGS. 3 to 5 , the connecting unit  121   a  between the lens unit  111  and the lens unit  112  is provided from an end of the gap  131   a  adjacent to the lower surface  301  to the lower surface  301 , for example. In addition, in the microlens  100  illustrated in  FIGS. 3 to 5 , the connecting unit  122   a  between the lens unit  111  and the lens unit  112  is provided from an end of the gap  131   a  adjacent to the lateral surface  302  to the lateral surface  302 , for example. 
     Although not illustrated, similarly, the connecting units  121   b  to  121   d  and  122   b  to  122   d  and the gaps  131   b  to  131   d  are provided between the adjacent lens units among the lens units  112  to  115 . 
     According to the microlens  100  illustrated in  FIGS. 3 to 5 , similar to the microlens  100  illustrated in  FIG. 1 , the oblique light beams, which have been incident to the lens units  111  to  115 , are totally reflected when the oblique light beams reach the gaps  131   a  to  131   d , and as a result, it is possible to suppress the oblique light beams from leaking to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIGS. 3 to 5 , it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  111  to  115 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     According to the microlens  100  illustrated in  FIGS. 3 to 5 , the traveling direction of the light, which has been incident to the microlens  100 , may be changed by 90 degrees. Therefore, for example, the light, which has been emitted from the VCSEL perpendicularly to the board, is changed to be parallel to the board, so that the light may be incident to the optical fiber provided in parallel with the board. 
     Optical Module According to First Embodiment 
       FIG. 6  is a cross-sectional view illustrating an example of the optical module according to the first embodiment. In  FIG. 6 , constituent elements identical to the constituent elements in  FIGS. 3 to 5  are denoted by the same reference numerals, and descriptions thereof will be omitted. An optical module  600  according to the first embodiment illustrated in  FIG. 6  is an example of the optical module having the microlens  100  illustrated in  FIGS. 3 to 5 . For example, the optical module  600  is an optical module that converts an electrical signal, which has been inputted from a server or the like, into an optical signal and outputs the converted optical signal from the optical fibers  161  to  165 . 
     As illustrated in  FIG. 6 , the optical module  600  has, for example, a board  610 , a lens block  620 , and an exterior member  630 . The board  610  is electrically connected to a motherboard  650  of a server or the like through a connector  651  of the motherboard  650 . Therefore, an electrical signal is inputted to the optical module  600  from the motherboard  650 . In addition, for example, the VCSEL  151  and a drive circuit  611  are provided on the board  610 . 
     The drive circuit  611  creates a driving signal for the VCSEL  151  based on the electrical signal inputted to the board  610  and outputs the created driving signal to the VCSEL  151 . The VCSEL  151  outputs an optical signal by operating based on the driving signal inputted from the drive circuit  611 , thereby converting the electrical signal, which has been inputted to the board  610 , into the optical signal. 
     Although not illustrated, similarly, the VCSELs  152  to  155  are also provided on the board  610 , for example. Further, the drive circuit  611  creates driving signals for the VCSELs  152  to  155  based on the electrical signals inputted to the board  610  and outputs the created driving signals to the VCSELs  152  to  155 . The VCSELs  152  to  155  output optical signals by operating based on the driving signals inputted from the drive circuit  611 , thereby converting the electrical signals, which have been inputted to the board  610 , into the optical signals. 
     A non-illustrated optical modulator may be provided on the board  610 . In this case, the VCSELs  151  to  155  emit continuous light. In addition, for example, the drive circuit  611  creates a driving signal for the optical modulator based on the electrical signal inputted to the board  610  and outputs the created driving signal to the optical modulator. The optical modulator operates based on the driving signal inputted from the drive circuit  611  and modulates the continuous light emitted from the VCSELs  151  to  155 , thereby converting the electrical signal, which has been inputted to the board  610 , into the optical signal. 
     As illustrated in  FIG. 6 , the drive circuit  611  may be thermally connected to the exterior member  630  through a thermal block  612  made of copper or the like. Therefore, it is possible to decrease a temperature of the drive circuit  611  by removing heat of the drive circuit  611  to the exterior member  630 . 
     The lens block  620  has the microlens  100 , and a support unit  621  which supports the microlens  100 . For example, the lens block  620  is implemented by integrally forming the microlens  100  and the support unit  621  and fixed to the board  610  as the support unit  621  is attached to the board  610 . 
     The optical fiber (e.g., the optical fiber  161 ) inserted into the optical module  600  is fixed to the lens block  620 , for example, by an MT ferrule  622  and an MT clip  623 . The lens block  620  and the periphery of the lens block  620  will be described below with reference to  FIG. 7 . MT stands for Mechanically Transferable. 
     The exterior member  630  is provided to surround the board  610  and the lens block  620 . An opening  631  is provided in the exterior member  630 . The optical fiber  161  is inserted into the exterior member  630  from the outside through the opening  631 . In addition, although not illustrated, for example, similar to the optical fiber  161 , the optical fibers  162  to  165  are also inserted into the exterior member  630  from the outside through the opening  631 . 
     As illustrated in  FIG. 6 , the exterior member  630  may be thermally connected to a heat sink  641  and a cooling unit  642 . For example, the cooling unit  642  includes a heat dissipation plate which is provided such that a lower surface thereof is in contact with the heat sink  641 , and a heat pipe which is provided to be in contact with an upper surface of the heat dissipation plate. Therefore, heat of the exterior member  630  is removed to the heat sink  641  and the cooling unit  642 , so that a temperature of or in the exterior member  630  may be decreased. 
       FIG. 7  is a cross-sectional view illustrating an example of a part of the optical module according to the first embodiment. For example,  FIG. 7  is an enlarged view illustrating the lens block  620  and the periphery of the lens block  620  illustrated in  FIG. 6 . 
     As illustrated in  FIG. 7 , in the optical module  600 , the microlens  100  is, for example, fixed to the board  610  in a state where the convex lens portion  111   a  and the VCSEL  151  face each other. Further, in the optical module  600 , the optical fiber  161  is fixed to the lens block  620  by the MT ferrule  622  and the MT clip  623  in the state where the end of the optical fiber  161  faces the convex lens portion  111   b.    
     Therefore, in the optical module  600 , as indicated by the arrow  700 , the laser beam emitted from the VCSEL  151  is incident to the microlens  100  from the convex lens portion  111   a . Further, the traveling direction of the laser beam, which has been incident from the convex lens portion  111   a , is changed by 90 degrees toward the convex lens portion  111   b , so that the laser beam is emitted from the convex lens portion  111   b  and then incident to the optical fiber  161 . The laser beam, which has been incident to the optical fiber  161 , is transmitted to the corresponding device of the optical module  600  through the optical fiber  161 . 
     Although not illustrated, similarly, in the optical module  600 , the microlens  100  is, for example, fixed to the board  610  in a state where the convex lens portions  112   a  to  115   a  face the VCSELs  152  to  155 , respectively. Further, in the optical module  600 , the optical fibers  162  to  165  are fixed to the lens block  620  by the MT ferrule  622  and the MT clip  623  in the state where the ends of the optical fibers  162  to  165  face the convex lens portions  112   b  to  115   b.    
     Therefore, in the optical module  600 , the laser beams emitted from the VCSELs  152  to  155  are incident to the microlens  100  from the convex lens portions  112   a  to  115   a . Further, the traveling directions of the laser beams, which have been incident from the convex lens portions  112   a  to  115   a , are changed by 90 degrees toward the convex lens portions  112   b  to  115   b , so that the laser beams are emitted from the convex lens portions  112   b  to  115   b  and then incident to the optical fibers  162  to  165 . The laser beams, which have been incident to the optical fibers  162  to  165 , are transmitted to the corresponding device of the optical module  600  through the optical fibers  162  to  165 . 
     In the optical module  600 , for example, the PDs  191  to  195  may be provided on the board  610  instead of the VCSELs  151  to  155 . For example, in the case where the PDs  191  to  195  are provided, the laser beams are incident to the optical fibers  161  to  165  from the corresponding device of the optical module  600 . Further, the optical fibers  161  to  165  output the laser beams, which have been incident from the corresponding device of the optical module  600 , to the convex lens portions  111   b  to  115   b , respectively. The traveling directions of the laser beams, which have been incident from the convex lens portions  111   b  to  115   b , are changed by 90 degrees, so that the laser beams are emitted from the convex lens portions  111   a  to  115   a . Further, the PDs  191  to  195  receive the laser beams emitted from the convex lens portions  111   a  to  115   a , respectively. The drive circuit  611  converts the optical signals received by the PDs  191  to  195  into electrical signals and outputs the converted electrical signals to the motherboard  650  through the connector  651 , for example. 
     The corresponding device of the optical module  600  having the VCSELs  151  to  155  may be changed to the optical module  600  that has the PDs  191  to  195  instead of the VCSELs  151  to  155 . In addition, the configuration of the optical module  600  is not limited thereto, and for example, the optical module  600  may be an optical transceiver that has all of the VCSELs  151  to  155  and the PDs  191  to  195  and transmits and receives optical signals. 
     In this way, the optical module  600  according to the first embodiment has, between the multiple lens units in the microlens  100 , the connecting units that connect the lens units, and the gaps where the lens units are not connected to one another. Therefore, the multiple lens units are fixed to one another by the connecting units that connect the lens units, and the respective optical axes of the multiple lens units may be aligned without individually positioning or adjusting the multiple lens units. In addition, the oblique light beam, which has been incident to the lens unit, is totally reflected by the gap where the lens units are not connected to each other, and as a result, it is possible to suppress the oblique light beam from leaking to the neighboring lens unit. 
     Second Embodiment 
     Parts of a second embodiment, which are different from the parts of the first embodiment, will be described. The second embodiment to be described below is, for example, an example in which a light shielding plate, which shields the laser beams emitted from the VCSELs  151  to  156  so as not to be incident to the neighboring lens unit, is provided. 
     Example of Microlens According to Second Embodiment 
       FIG. 8  is a front view illustrating an example of the microlens according to the second embodiment.  FIG. 9  is a top plan view illustrating an example of the microlens according to the second embodiment. In  FIG. 8 , constituent elements identical to the constituent elements in  FIG. 1  are denoted by the same reference numerals, and descriptions thereof will be omitted. In addition, in  FIG. 9 , constituent elements identical to the constituent elements in  FIG. 2  are denoted by the same reference numerals, and descriptions thereof will be omitted. 
     In the microlens  100  according to the second embodiment illustrated in  FIGS. 8 and 9 , light shielding plates  801  to  805  are provided between the adjacent lens units among the lens units  111  to  116 . For example, the light shielding plate  801  is provided between the convex lens portion  111   a  and the convex lens portion  112   a  and shields the laser beam  172   a  emitted from the VCSEL  152  so as not to be incident to the neighboring convex lens portion  111   a . In addition, the light shielding plate  801  may shield the laser beam  171   a  emitted from the VCSEL  151  so as not to be incident to the neighboring convex lens portion  112   a.    
     For example, the light shielding plate  801  is provided at a portion of the connecting unit  121   a  adjacent to the VCSELs  151  and  152  between the lens unit  111  and the lens unit  112 . In addition, the light shielding plate  801  is provided to protrude further toward the VCSELs  151  and  152  than the convex lens portions  111   a  and  112   a . In addition, a material that reflects light and does not transmit light may be deposited or applied onto portions of the light shielding plate  801  adjacent to the convex lens portions  111   a  and  112   a . An example of the material that reflects light and does not transmit light is gold. With the configuration, the light shielding plate  801  may shield the laser beam  172   a  emitted from the VCSEL  152  so as not to be incident to the convex lens portion  111   a , and the light shielding plate  801  may shield the laser beam  171   a  emitted from the VCSEL  151  so as not to be incident to the convex lens portion  112   a.    
     For this reason, the light shielding plate  801  may reduce crosstalk occurring when the laser beam  172   a  emitted from the VCSEL  152  is incident to the convex lens portion  111   a , thereby reducing deterioration in optical signal caused by the crosstalk. In addition, the light shielding plate  801  may reduce crosstalk occurring when the laser beam  171   a  emitted from the VCSEL  151  is incident to the convex lens portion  112   a , thereby reducing deterioration in optical signal caused by the crosstalk. 
     Similarly, the light shielding plates  802  to  805  are provided at portions of the connecting units  121   b  to  121   e  adjacent to the VCSELs  152  to  156  between the adjacent convex lens portions among the convex lens portions  112   a  to  116   a . In addition, the light shielding plates  802  to  805  are provided to protrude further toward the VCSELs  152  and  156  than the convex lens portions  112   a  and  116   a . In addition, a material that reflects light and does not transmit light may be deposited or applied onto portions of the light shielding plates  802  to  805  adjacent to the convex lens portions  112   a  and  116   a . With the configuration, the light shielding plates  802  to  805  may shield the laser beams  172   a  to  176   a  emitted from the VCSELs  152  to  156  so as not to be incident to the neighboring convex lens portions. For this reason, the light shielding plates  802  to  805  may reduce crosstalk occurring when the laser beams  172   a  to  176   a  emitted from the VCSELs  152  to  156  are incident to the neighboring convex lens portions, thereby reducing deterioration in the optical signal caused by crosstalk. 
     For example, the light shielding plate  801  reflects the laser beam, which has reached the light shielding plate  801  among the laser beams  171   a  emitted from the VCSEL  151 , toward the convex lens portion  111   a , thereby allowing the laser beam to be incident to the convex lens portion  111   a . For this reason, the light shielding plate  801  may suppress deterioration in intensity of the laser beam incident to the convex lens portion  111   a.    
     Similarly, for example, the light shielding plates  802  to  805  may reflect the laser beams, which have reached the light shielding plates  802  to  805  among the laser beams  172   a  to  176   a  emitted from the VCSELs  152  to  156 , toward the convex lens portions  112   a  to  116   a . Therefore, the light shielding plates  802  to  805  may allow the laser beams, which have reached the light shielding plates  802  to  805  among the laser beams  172   a  to  176   a  emitted from the VCSELs  152  to  156 , to be incident to the convex lens portions  112   a  to  116   a . For this reason, the light shielding plates  802  to  805  may suppress deterioration in the intensity of the laser beams incident to the convex lens portions  112   a  to  116   a.    
     For example, in the microlens  100  according to the second embodiment, the portions of the lens units  111  to  116 , the connecting units  121   a  to  121   e  and  122   a  to  122   e , and the light shielding plates  801  to  805  are integrally formed by using a mold and by using resin or the like. Further, the microlens  100  according to the second embodiment may be implemented by integrally forming the lens units  111  to  116 , the connecting units  121   a  to  121   e  and  122   a  to  122   e , and the light shielding plates  801  to  805 , and then depositing gold on the portions of the light shielding plates  801  to  805 . Therefore, it is possible to easily form the microlens  100  having the lens units  111  to  116  in which the directions of the optical axes and the pitch are constant, and the gaps  131   a  to  131   e  and the light shielding plates  801  to  805 . 
     In the example described above, the light shielding plates  801  to  805  are configured to reflect light, but the light shielding plates  801  to  805  are not limited thereto. For example, a material, which absorbs light, is deposited or applied onto the portions of the light shielding plates  801  to  805  adjacent to the convex lens portions  111   a  to  116   a , so that the light shielding plates  801  to  805  may absorb light. 
     As described above, according to the microlens  100  illustrated in  FIGS. 8 and 9 , similar to the microlens  100  according to the first embodiment, the oblique light beams, which have been incident to the lens units  111  to  116 , are totally reflected when the oblique light beams reach the gaps  131   a  to  131   e . Therefore, according to the microlens  100  illustrated in  FIGS. 8 and 9 , it is possible to suppress the oblique light beams, which have been incident to the lens units  111  to  116 , from leaking to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIGS. 8 and 9 , it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  111  to  116 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     According to the microlens  100  illustrated in  FIGS. 8 and 9 , the laser beams  171   a  to  176   a  emitted from the VCSELs  151  to  156  may be shielded by the light shielding plates  801  to  805  so as not to be incident to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIGS. 8 and 9 , it is possible to reduce crosstalk occurring when the laser beams  171   a  to  176   a  emitted from the VCSELs  151  to  156  are incident to the neighboring lens units, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     In the example described above, the VCSELs  151  to  156  are provided, but the operations of the light shielding plates  801  to  805  are not limited thereto. For example, as illustrated in  FIG. 8 , the PD  191  may be provided instead of the VCSEL  151 . In the case where the PD  191  is provided, the light shielding plate  801  may shield the laser beam, which has been emitted from the convex lens portion  112   a , so as not to be incident to the PD  191  For this reason, according to the microlens  100  illustrated in  FIGS. 8 and 9 , it is possible to reduce crosstalk occurring when the laser beam, which has been emitted from the convex lens portion  112   a , is incident to the PD  191 , and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     Similarly, in the microlens  100  illustrated in  FIGS. 8 and 9 , the PDs  192  to  196  may be provided instead of the VCSELs  152  to  156 . In the case where the PDs  192  to  196  are provided, the light shielding plates  802  to  805  may shield the laser beams, which have been emitted from the convex lens portions  112   a  to  116   a , so as not to be incident to the neighboring PDs. For this reason, according to the microlens  100  illustrated in  FIGS. 8 and 9 , it is possible to reduce crosstalk occurring when the laser beams, which have been emitted from the convex lens portions  112   a  to  116   a , are incident to the neighboring PDs, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     Another Example of Microlens According to Second Embodiment 
     Another example of the microlens  100  according to the second embodiment to be described below is an example in which the optical path changing unit  500 , which changes the traveling direction of the light which has been incident to the microlens  100 , is provided in the microlens  100  according to the second embodiment. 
       FIG. 10  is a bottom view illustrating another example of the microlens according to the second embodiment.  FIG. 11  is a top plan view illustrating another example of the microlens according to the second embodiment. In  FIG. 10 , constituent elements identical to the constituent elements in  FIGS. 3 and 8  are denoted by the same reference numerals, and descriptions thereof will be omitted. In  FIG. 11 , constituent elements identical to the constituent elements in  FIGS. 4 and 8  are denoted by the same reference numerals, and descriptions thereof will be omitted. 
     In the microlens  100  illustrated in  FIGS. 10 and 11 , for example, the light shielding plates  801  to  804  are provided between the adjacent convex lens portions among the convex lens portions  111   a  to  115   a  on the lower surface  301  and provided to protrude from the lower surface  301 . 
       FIG. 12  is a cross-sectional view illustrating another example of the microlens according to the second embodiment. For example,  FIG. 12  illustrates an example of a cross section of the microlens  100  illustrated in  FIGS. 10 and 11  taken along line B-B in  FIG. 11  when viewed in a direction from the bottom to the top in  FIG. 11 . As illustrated in  FIG. 12 , for example, the light shielding plate  801  between the convex lens portion  111   a  and the convex lens portion  112   a  is provided to further protrude from the lower surface  301  than the convex lens portion  111   a . In addition, although not illustrated, similarly, the light shielding plates  802  to  804  are provided to further protrude from the lower surface  301  than the convex lens portions  112   a  to  115   a.    
     According to the microlens  100  illustrated in  FIGS. 10 to 12 , similar to the microlens  100  illustrated in  FIG. 8 , the oblique light beams, which have been incident to the lens units  111  to  115 , are totally reflected when the oblique light beams reach the gaps  131   a  to  131   d , and as a result, it is possible to suppress the oblique light beams from leaking to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIGS. 10 to 12 , it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  111  to  115 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. In addition, according to the microlens  100  illustrated in  FIGS. 10 to 12 , the traveling direction of the light, which has been incident to the microlens  100 , may be changed by 90 degrees. 
     According to the microlens  100  illustrated in  FIGS. 10 to 12 , the laser beams emitted from the VCSELs  151  to  155  may be shielded by the light shielding plates  801  to  804  so as not to be incident to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIGS. 10 to 12 , it is possible to reduce crosstalk occurring when the laser beams emitted from the VCSELs  151  to  155  are incident to the neighboring lens units, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     According to the microlens  100  illustrated in  FIGS. 10 to 12 , the laser beams, which have been emitted from the lens units  111  to  115 , may be shielded by the light shielding plates  801  to  804  so as not to be incident to the neighboring PDs. For this reason, according to the microlens  100  illustrated in  FIGS. 10 to 12 , it is possible to reduce crosstalk occurring when the laser beams, which have been emitted from the lens units  111  to  115 , are incident to the neighboring PDs, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     Example of Optical Module According to Second Embodiment 
     For example, the optical module  600  according to the second embodiment is made by substituting the microlens  100  of the optical module  600  according to the first embodiment illustrated in  FIG. 6  with the microlens  100  illustrated in  FIGS. 10 to 12 . 
     For this reason, according to the optical module  600  according to the second embodiment, similar to the microlens  100  illustrated in  FIGS. 10 to 12 , the oblique light beams, which have been incident to the lens units  111  to  115 , are totally reflected when the oblique light beams reach the gaps  131   a  to  131   d . Therefore, according to the optical module  600  according to the second embodiment, it is possible to suppress the oblique light beams, which have been incident to the lens units  111  to  115 , from leaking to the neighboring lens units. For this reason, according to the optical module  600  according to the second embodiment, it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  111  to  115 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     According to the optical module  600  according to the second embodiment, similar to the microlens  100  illustrated in  FIGS. 10 to 12 , the laser beams emitted from the VCSELs  151  to  155  may be shielded by the light shielding plates  801  to  804  so as not to be incident to the neighboring lens units. For this reason, according to the optical module  600  according to the second embodiment, it is possible to reduce crosstalk occurring when the laser beams emitted from the VCSELs  151  to  155  are incident to the neighboring lens unit, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     According to the optical module  600  according to the second embodiment, the laser beams, which have been emitted from the lens units  111  to  115 , may be shielded by the light shielding plates  801  to  804  so as not to be incident to the neighboring PDs. For this reason, according to the optical module  600  according to the second embodiment, it is possible to reduce crosstalk occurring when the laser beams, which have been emitted from the lens units  111  to  115 , are incident to the neighboring PDs, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     In this way, according to the optical module  600  according to the second embodiment, similar to the optical module  600  according to the first embodiment, it is possible to suppress the oblique light beam, which has been incident to the lens unit, from leaking to the neighboring lens unit. In addition, according to the optical module  600  according to the second embodiment, the light shielding plates are provided between the respective lens units at the light incidence side of the microlens  100 , and as a result, it is possible to suppress the oblique light beam, before being incident to the lens unit, from being incident to the neighboring lens unit. Alternatively, according to the optical module  600  according to the second embodiment, the light shielding plates are provided between the respective lens units at the light emission side of the microlens  100 , and as a result, it is possible to suppress the oblique light beam, which has been emitted from the lens unit to the PD, from being incident to the neighboring PD. For this reason, according to the optical module  600  according to the second embodiment, it is possible to reduce deterioration in optical signal. 
     Third Embodiment 
     Parts of a third embodiment, which are different from the parts of the first embodiment, will be described. The third embodiment to be described below is, for example, an example in which a light shielding film, which shields the laser beams emitted from the VCSELs  151  to  156  so as not to be incident to the neighboring lens unit, is provided. 
     Example of Microlens According to Third Embodiment 
       FIG. 13  is a front view illustrating an example of a microlens according to the third embodiment.  FIG. 14  is a top plan view illustrating an example of the microlens according to the third embodiment. In  FIG. 13 , constituent elements identical to the constituent elements in  FIG. 1  are denoted by the same reference numerals, and descriptions thereof will be omitted. In addition, in  FIG. 14 , constituent elements identical to the constituent elements in  FIG. 2  are denoted by the same reference numerals, and descriptions thereof will be omitted. 
     In the microlens  100  according to the third embodiment illustrated in  FIGS. 13 and 14 , light shielding films  1301  to  1306  are provided on the lens units  111  to  116 . For example, the light shielding films  1301  are provided on the convex lens portion  111   a  and shield the laser beam  172   a  emitted from the VCSEL  152  so as not to be incident to the convex lens portion  111   a.    
     For example, the light shielding film  1301  is provided by depositing or applying a material that reflects light and does not transmit light, such as gold, on a part of a surface of the convex lens portion  111   a  which is adjacent to the neighboring convex lens portion  112   a . Therefore, the light shielding film  1301  may shield the laser beam  172   a  emitted from the VCSEL  152  so as not to be incident to the convex lens portion  111   a . Therefore, the light shielding film  1301  may reduce crosstalk occurring when the laser beam  172   a  emitted from the VCSEL  152  is incident to the convex lens portion  111   a , thereby reducing deterioration in optical signal caused by the crosstalk. 
     Similarly, the light shielding films  1302  are provided on the convex lens portion  112   a  and shield the laser beam  171   a  emitted from the VCSEL  151  so that the laser beam  171   a  does not enter the convex lens portion  112   a . In addition, the light shielding film  1302  may shield the laser beam  173   a  emitted from the VCSEL  153  opposite to the VCSEL  151  so as not to be incident to the convex lens portion  112   a.    
     For example, the light shielding film  1302  is provided by depositing or applying a material that reflects light and does not transmit light, on a part of a surface of the convex lens portion  112   a  adjacent to the convex lens portion  111   a  and on a part of the convex lens portion  113   a . Therefore, the light shielding film  1302  may shield the laser beam  171   a  emitted from the VCSEL  151  so as not to be incident to the convex lens portion  112   a . In addition, therefore, the light shielding film  1302  may shield the laser beam  173   a  emitted from the VCSEL  153  so as not to be incident to the convex lens portion  112   a . Therefore, the light shielding film  1302  may reduce crosstalk corresponding when the laser beam  171   a  emitted from the VCSEL  151  or the laser beam  173   a  emitted from the VCSEL  153  is incident to the convex lens portion  112   a , thereby reducing deterioration in the optical signal caused by crosstalk. 
     Similarly, the light shielding films  1303  to  1306  are provided on the convex lens portions  113   a  to  116   a  and shield the laser beams emitted from the neighboring VCSELs so as not to be incident to the convex lens portions  113   a  to  116   a . In addition, for example, each of the light shielding films  1303  to  1306  is provided by depositing or applying a material that reflects light and does not transmit light, on a part of a surface of each of the convex lens portions  113   a  to  116   a  adjacent to the convex lens portion. Therefore, the light shielding films  1303  to  1306  may shield the laser beams emitted from the neighboring VCSELs so that the laser beams do not are incident to the convex lens portions  113   a  to  116   a . Therefore, the light shielding films  1303  to  1306  may reduce crosstalk occurring when the laser beams emitted from the neighboring VCSELs are incident to the convex lens portions  113   a  to  116   a , thereby reducing deterioration in optical signal caused by the crosstalk. 
     For example, in the microlens  100  according to the third embodiment, the lens units  111  to  116  and the connecting units  121   a  to  121   e  and  122   a  to  122   e  are integrally formed by using a mold and by using resin or the like. Further, the microlens  100  according to the third embodiment may be implemented by integrally forming the lens units  111  to  116  and the connecting units  121   a  to  121   e  and  122   a  to  122   e  and then depositing gold on the portions of the light shielding films  1301  to  1306 . Therefore, it is possible to easily form the microlens  100  having the lens units  111  to  116  in which the directions of the optical axes and the pitch are constant, and the gaps  131   a  to  131   e  and the light shielding films  1301  to  1306 . 
     In the example described above, the light shielding films  1301  to  1306  are configured to reflect light, but the operations of the light shielding films  1301  to  1306  are not limited thereto. For example, a material, which absorbs light, may be deposited on the portions of the convex lens portions  111   a  to  116   a , which are configured as the light shielding films  1301  to  1306 , so that the light shielding films  1301  to  1306  may absorb light. 
     As described above, according to the microlens  100  illustrated in  FIGS. 13 and 14 , similar to the microlens  100  according to the first embodiment, the oblique light beams, which have been incident to the lens units  111  to  116 , are totally reflected when the oblique light beams reach the gaps  131   a  to  131   e . Therefore, according to the microlens  100  illustrated in  FIGS. 13 and 14 , it is possible to suppress the oblique light beams, which have been incident to the lens units  111  to  116 , from leaking to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIGS. 13 and 14 , it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  111  to  116 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     According to the microlens  100  illustrated in  FIGS. 13 and 14 , the laser beams emitted from the VCSELs  151  to  156  may be shielded by the light shielding films  1301  to  1305  so as not to be incident to the neighboring lens units  111  to  116 . For this reason, according to the microlens  100  illustrated in  FIGS. 13 and 14 , it is possible to reduce crosstalk occurring when the laser beams emitted from the VCSELs  151  to  155  are incident to the neighboring lens units  111  to  116 , and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     In the example described above, the VCSELs  151  to  156  are provided, but the configuration is not limited thereto. For example, as illustrated in  FIG. 13 , the PD  191  may be provided instead of the VCSEL  151 . In the case where the PD  191  is provided, the light shielding film  1302  may shield the laser beam, which has been emitted from the convex lens portion  112   a , so as not to be incident to the neighboring PD  191 . For this reason, according to the microlens  100  illustrated in  FIGS. 13 and 14 , it is possible to reduce crosstalk occurring when the laser beam, which has been emitted from the convex lens portion  112   a , is incident to the PD  191 , and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     Similarly, in the microlens  100  illustrated in  FIGS. 13 and 14 , the PDs  192  to  196  may be provided instead of the VCSELs  152  to  156 . In the case where the PDs  192  to  196  are provided, the light shielding films  1302  to  1306  may shield the laser beams, which have been emitted from the convex lens portions  112   a  to  116   a , so as not to be incident to the neighboring PDs. For this reason, according to the microlens  100  illustrated in  FIGS. 13 and 14 , it is possible to reduce crosstalk occurring when the laser beams, which have been emitted from the convex lens portions  112   a  to  116   a , are incident to the neighboring PDs, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     Another Example of Microlens According to Third Embodiment 
     Another example of the microlens  100  according to the third embodiment to be described below is an example in which the optical path changing unit  500 , which changes the traveling direction of the light which has been incident to the microlens  100 , is provided in the microlens  100  according to the third embodiment. Hereinafter, parts different from the parts of the microlens  100  illustrated in  FIGS. 3 to 5  will be described. 
       FIG. 15  is a bottom view illustrating another example of the microlens according to the third embodiment. In  FIG. 15 , constituent elements identical to the constituent elements in  FIGS. 3 and 13  are denoted by the same reference numerals, and descriptions thereof will be omitted. In the microlens  100  according to the third embodiment illustrated in  FIG. 15 , for example, the light shielding films  1301  to  1305  are provided on the convex lens portions  111   a  to  115   a  on the lower surface  301 . For example, the microlens  100  illustrated in  FIG. 15  is identical to the microlens  100  illustrated in  FIGS. 3 to 5  except that the light shielding films  1301  to  1305  are provided on the convex lens portions  111   a  to  115   a.    
     According to the microlens  100  illustrated in  FIG. 15 , similar to the microlens  100  illustrated in  FIG. 13 , the oblique light beams, which have been incident to the lens units  111  to  115 , are totally reflected when the oblique light beams reach the gaps  131   a  to  131   d , and as a result, it is possible to suppress the oblique light beams from leaking to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIG. 15 , it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  111  to  115 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     According to the microlens  100  illustrated in  FIG. 15 , similar to the microlens  100  illustrated in  FIG. 13 , the laser beams emitted from the VCSELs  151  to  155  may be shielded by the light shielding films  1301  to  1305  so as not to be incident to the neighboring lens units. For this reason, according to the microlens  100  illustrated in  FIG. 15 , it is possible to reduce crosstalk occurring when the laser beams emitted from the VCSELs  151  to  155  are incident to the neighboring lens units, and thus it is possible to reduce deterioration in optical signal caused by the crosstalk. 
     According to the microlens  100  illustrated in  FIG. 15 , similar to the microlens  100  illustrated in  FIG. 13 , the laser beams, which have been emitted from the convex lens portions  111   a  to  115   a , may be shielded by the light shielding films  1301  to  1305  so as not to be incident to the neighboring PDs. For this reason, according to the microlens  100  illustrated in  FIG. 15 , it is possible to reduce crosstalk occurring when the laser beams, which have been emitted from the convex lens portions  111   a  to  115   a , are incident to the neighboring PDs, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     Example of Optical Module According to Third Embodiment 
     For example, the optical module  600  according to the third embodiment is made by substituting the microlens  100  of the optical module  600  according to the first embodiment illustrated in  FIG. 6  with the microlens  100  illustrated in  FIG. 15 . 
     For this reason, according to the optical module  600  according to the third embodiment, similar to the microlens  100  illustrated in  FIG. 15 , the oblique light beams, which have been incident to the lens units  111  to  115 , are totally reflected when the oblique light beams reach the gaps  131   a  to  131   d , and as a result, it is possible to suppress the oblique light beams from leaking to the neighboring lens units. For this reason, according to the optical module  600  according to the third embodiment, it is possible to reduce crosstalk occurring when the oblique light beams, which have been incident to the lens units  111  to  115 , leak to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     According to the optical module  600  according to the third embodiment, similar to the microlens  100  illustrated in  FIG. 15 , the laser beams emitted from the VCSELs  151  to  155  may be shielded by the light shielding films  1301  to  1305  so as not to be incident to the neighboring lens units. For this reason, according to the optical module  600  according to the third embodiment, it is possible to reduce crosstalk occurring when the laser beams emitted from the VCSELs  151  to  155  are incident to the neighboring lens units, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     According to the optical module  600  according to the third embodiment, similar to the microlens  100  illustrated in  FIG. 15 , the laser beams, which have been emitted from the convex lens portions  111   a  to  115   a , may be shielded by the light shielding films  1301  to  1305  so as not to be incident to the neighboring PDs. For this reason, according to the optical module  600  according to the third embodiment, it is possible to reduce crosstalk occurring when the laser beams, which have been emitted from the convex lens portions  111   a  to  115   a , are incident to the neighboring PDs, and thus it is possible to reduce deterioration in the optical signal caused by crosstalk. 
     In this way, according to the optical module  600  according to the third embodiment, similar to the optical module  600  according to the first embodiment, it is possible to suppress the oblique light beam, which has been incident to the lens unit, from leaking to the neighboring lens unit. In addition, according to the optical module  600  according to the third embodiment, the light shielding films are provided at the light incidence side of the lens unit of the microlens  100 , and as a result, it is possible to suppress the oblique light beam, before being incident to the lens unit, from being incident to the neighboring lens unit. Alternatively, according to the optical module  600  according to the third embodiment, the light shielding film is provided at the light emission side of the lens unit of the microlens  100 , and as a result, it is possible to suppress the oblique light beam, which has been emitted from the lens unit to the PD, from being incident to the neighboring PD. For this reason, according to the optical module  600  according to the third embodiment, it is possible to reduce deterioration in optical signal. 
     The second embodiment and the third embodiment may be combined. For example, in this case, the light shielding plates  801  to  805  may be provided between the adjacent lens units among the lens units  111  to  116 , and the light shielding films  1301  to  1306  may be provided on the lens units  111  to  116 . 
     As described above, according to the optical module according to the present disclosure, it is possible to suppress the oblique light beam, which has been incident to the lens, from leaking to the neighboring lens. 
     For example, recently, a printed board used for a server or a super computer is increased in speed and density. For this reason, in terms of interconnection by electric wiring in the related art, sufficient characteristics cannot be expected due to delays, damping, and interference of signals. To solve these problems, an optical signal is used for interconnection on the printed board. In the case where the optical signal is used for the interconnection on the printed board, multiple light sources such as VCSELs are disposed with a narrow pitch, and as a result, leaking light may be incident to the adjacent light receiving element. Crosstalk caused by the leaking light cannot be ignored in accordance with the increase in speed of signals. 
     In contrast, for example, according to the first embodiment, the gap  131   a  is provided between the lens unit  111  and the lens unit  112 . For this reason, according to the first embodiment, it is possible to suppress the laser beam, which has been incident to the lens unit  111  from the VCSEL  151 , as leaking light, from being incident to the lens unit  112  adjacent to the lens unit  111 . In addition, similarly, it is possible to suppress the laser beam, which has been incident to the lens unit  112  from the VCSEL  152 , as leaking light, from being incident to the lens unit  111  adjacent to the lens unit  112 . 
     According to the second embodiment, the light shielding plate  801  is provided between the lens unit  111  and the lens unit  112 . For this reason, according to the second embodiment, it is possible to suppress the laser beam emitted from the VCSEL  151  from being incident to the lens unit  112  adjacent to the lens unit  111 . In addition, similarly, it is possible to suppress the laser beam emitted from the VCSEL  152  from being incident to the lens unit  111  adjacent to the lens unit  112 . 
     According to the third embodiment, the light shielding film  1301  is provided on the lens unit  111 , and the light shielding film  1302  is provided on the lens unit  112 . For this reason, according to the third embodiment, it is possible to suppress the laser beam emitted from the VCSEL  151  from being incident to the lens unit  112  adjacent to the lens unit  111 . In addition, similarly, it is possible to suppress the laser beam emitted from the VCSEL  152  from being incident to the lens unit  111  adjacent to the lens unit  112 . 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to an illustrating of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.