Abstract:
A method for manufacturing an optical waveguide interconnect may comprise providing a substrate, irradiating portions of the substrate&#39;s interior volume by directing a processing laser beam into the substrate surface, thus defining one or more surfaces that function as optic components, forming an embedded waveguide in the interior volume by directing the processing laser beam into the substrate surface, and etching away the weakened portions of the substrate&#39;s interior volume overlying the defined surfaces using an etchant. The optic components and the waveguide may be aligned to be in optical communication with each other such that an input beam of light may strike the defined surface of a first optic component, traverse the waveguide, and strike the defined surface of a second optic component.

Description:
[0001]    This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 62/160816 filed on May 13, 2015, the content of which is relied upon and incorporated herein by reference in its entirety. 
     
    
     FIELD 
       [0002]    The present disclosure generally relates to optic components, optical waveguide interconnects, and methods for manufacturing the same. 
       BACKGROUND 
       [0003]    Optical waveguide interconnects may be used to address issues with bandwidth bottlenecks potentially limited by the use of electrical wire at circuit board levels. Polymeric waveguides are often employed, but can be limited in high bandwidth applications by poor thermal stability characteristics. The present disclosure relates to an integrated laser manufacturing solution to manufacture board-level optical waveguide interconnects, such as those made in a glass substrate. 
       SUMMARY 
       [0004]    Optionally, a method for manufacturing an optic component may comprise providing a substrate having a surface and an interior volume of solid material; and irradiating a portion of the interior volume by directing a processing laser beam into the substrate surface. The irradiating may be carried out under conditions effective to expose and weaken the solid material within the irradiated portion, which may define a surface, optionally further including solid material adjacent to the surface that functions as an optic component. 
         [0005]    Optionally, a method for manufacturing an optical waveguide interconnect may comprise providing a substrate having a surface and an interior volume of solid material; and, irradiating at least two portions of the interior volume by directing a processing laser beam into the substrate surface. The irradiating may be carried out under conditions effective to expose and weaken the solid material overlying the at least two portions, which may define first and second surfaces, optionally further including solid material adjacent to one or more of the surfaces, that function as first and second optic components. The method for manufacturing may further comprise forming an embedded waveguide in the interior volume by directing the processing laser beam into the substrate surface and etching away the weakened portions of the interior volume overlying the first and second defined surfaces using an etchant. The first and second optic components and the waveguide may be aligned to be in optical communication with each other such that an input beam of light may strike the defined surface of the first optic component, traverse the waveguide, and strike the defined surface of the second optic component. 
         [0006]    Optionally, an optical interconnect may comprise an opto-electronic device configured to transmit or receive light; and a substrate having a surface and containing an embedded input optic component having a first exposed surface, an embedded waveguide, and an embedded output optic component having a second exposed surface. The optic components and the embedded waveguide may be aligned to be in optical communication with each other. 
         [0007]    Additional features and advantages of the present disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
         [0008]    It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0009]    The following is a description of the figures in the accompanying drawings. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity or conciseness. 
           [0010]      FIG. 1 a    shows an example of an optical component prior to removal of an irradiated portion. 
           [0011]      FIG. 1 b    shows a cross-sectional view of an example of an optical component prior to removal of an irradiated portion. 
           [0012]      FIG. 2 a    shows an example of an optical component prior to heat treatment. 
           [0013]      FIG. 2 b    shows an enlarged view of the optical component surface encircled in  FIG. 2   a.    
           [0014]      FIG. 3 a    shows an example of an optical component subsequent to heat treatment. 
           [0015]      FIG. 3 b    shows an enlarged view of the optical component surface encircled in  FIG. 3   a.    
           [0016]      FIG. 4 a    shows an example of a pair of optically-coupled optical components separated by a waveguide. 
           [0017]      FIG. 4 b    shows an example of a pair of optically-coupled optical component separated by a waveguide and waveguide splitter. 
           [0018]      FIG. 5  shows an example of a waveguide splitter or coupler. 
           [0019]      FIG. 6  shows an example of an optical fiber mounted on a substrate. 
           [0020]      FIG. 7 a    shows an example of a guided-mode image of light that has traversed an optical fiber prior to reflecting off an optical component. 
           [0021]      FIG. 7 b    shows an example of a guided-mode image of light that has traversed an optical fiber subsequent to reflecting off an optical component such as the optical component illustrated in  FIG. 1   b.    
           [0022]      FIG. 7 c    shows an example of a guided-mode image of light that has traversed an optical fiber subsequent to reflecting off an optical component such as the optical component illustrated in  FIG. 2   a.    
       
    
    
       [0023]    The following reference characters are used in this specification:
     10  Substrate     12  Substrate surface     14  Interior volume     15  Portion     20  Optic component     20   a  Optic component     20   b  Optic component     22  Defined surface     25  Waveguide     27  Waveguide splitter     30  Nanograting     40  Input beam     42  Output beam     50  Opto-electronic device     52  Optic fiber   
 
         [0039]    The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the figures. It should be understood that the claims are not limited to the arrangements and instrumentalities shown in the figures. Furthermore, the appearance shown in the figures is one of many ornamental appearances that can be employed to achieve the stated functions of the apparatus. 
       DETAILED DESCRIPTION 
       [0040]    In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be clear to one skilled in the art that the present invention can be practiced without some or all of these specific details. In other instances, well-known features or processes may not be described in detail so as not to unnecessarily obscure the invention. In addition, like or identical reference numerals may be used to identify common or similar elements. 
         [0041]      FIGS. 1 a , 1 b   ,  2   a,    2   b,    3   a,  and  3   b  illustrate an example of a substrate  10  of the present disclosure, in which an optic component  20  has been formed. The substrate  10  may be a silica glass. The substrate may have a substrate surface  12  and an interior volume  14 . The optic component  20  may be formed via irradiation by focusing a processing laser beam to expose and weaken a portion  15  of the interior volume  14 . By irradiating this portion  15 , a surface  22  may be defined. The defined surface  22  may function as an optic component  20 . The irradiating may be performed by stairstep scanning a processing laser beam across the substrate surface  12  while focusing the processing laser beam at varying depths within the interior volume  14  to weaken the irradiated portion  15  overlying the defined surface  22 . The processing laser beam may be generated, for example, by a deep UV (&lt;351 nm) or a short pulse (&lt;20 ps) laser source. For example, an ultrafast Ti:sapphire laser source may be used as the processing laser beam. The processing laser beam may be spatially shaped, for example using a cylindrical telescope, and may be focused into the substrate  10 , for example using an aberration-corrected objective lens. The weakened irradiated portion  15  may be removed by using an etchant, such as a hydrofluoric acid (HF) solution. 
         [0042]    Advantages of using the combined irradiating and etching manufacturing processes include greater accuracy (allowing for the introduction of finer details) and less damage to surrounding areas of the substrate  10  (for example, only the irradiated area is altered and no ablation debris is generated). Another advantage of the methods of the present disclosure is that the optic component  20  may be embedded. 
         [0043]    The processing laser beam may be used to write an embedded waveguide  25  (as shown schematically in  FIGS. 4 a  and 4 b   ) into the interior volume  14 . The embedded waveguide  25  may remain intact during etching of the substrate  10 . 
         [0044]    The optic component  20  may be any optic component that can be formed by the irradiation method described in the present disclosure. There are a number of known types of optic components that may be fabricated in this way, including optic components described by C. Debaes et al. in “Low-cost Micro-optical Modules for Board Level Optical Interconnections,” IEEE LEOS Newsletter Vol. 19, No. 3 (June 2005), available at http://photonicssociety.org/newsletters/jun05/hot_topic2. html; and described by S. V. Kartalopoulos in “Introduction to DWDM Technology: Data in a Rainbow—Chapter 4: Optical Spectral Filters and Gratings,” Wiley-IEEE Press (Dec. 1999), both of which are hereby incorporated by reference in their entireties. For example, the optic component  20  may be a mirror, a prism, a waveguide, a free space beam splitter, a waveguide, a waveguide splitter, a coupler, a waveguide coupler, a lens, a filter, a grating filter, a polarizer, a resonator, or a wavelength-division multiplexer (WDM). A mirror may be used to totally internally reflect beams of light. A mirror may be, for example, a 45 degree micro-mirror. A prism may be used as a free space beam splitter by partially internally reflecting a beam of light and partially refracting the beam of light. A waveguide, such as an embedded waveguide, may be used to direct a beam of light along a defined path. The waveguide may include a waveguide splitter, such as a 1×2 waveguide splitter, which may be Y-branched (as shown schematically in  FIG. 5 ), or a waveguide coupler, such as a 2×1 waveguide coupler, which may also be Y-branched (as shown schematically in  FIG. 5 ). A lens may be used to, for example, refocus a beam of light. A series of optic components  20 ,  20  may be used as a grating filter. 
         [0045]    One of the advantages of the present disclosure is the ability to create a series of multiple optic components that may be optically connected by one or more embedded waveguides. The optic components may be connected without significant signal loss due to, e.g., scattering. 
         [0046]    As shown in  FIGS. 2 a  and 2 b   , the defined surface  22  of the optic component  20  may have surface roughness in the form of nanograting  30  (such as microscopic or sub-microscopic grooves or ridges) as a result of the irradiation process. The nanograting  30  may be formed during irradiating by the processing laser beam. For clarity, the nanograting  30  is not shown in  FIGS. 1 a  and 1 b   , but it may be present prior to removal of the weakened irradiated portion  15 . To reduce the surface roughness, the optic component  20  may be heated to cause the defined surface  20  to flow. To create localized heat at the optic component  20 , a heat source such as a radiation source (e.g., a CO 2  laser) or a furnace may be used. As shown in  FIGS. 3 a  and 3 b   , the surface roughness of the defined surface  22  may be reduced by the heat treatment. As shown in  FIG. 3 a   , the heat treatment may introduce a slight curvature to the defined surface  22 . The surface roughness may be reduced to below  100  nm over a 100×100 μm area or to such a level that the scattering loss of an input beam of light  40  reflecting off the defined surface  22  is kept below 1 dB and as low as 0.2 dB, alternatively as low as 0.3 dB, alternatively as low as 0.4 dB, alternatively as low as 0.5 dB, alternatively as low as 0.6 dB, alternatively as low as 0.7 dB, alternatively as low as 0.8 dB, alternatively as low as 0.9 dB. 
         [0047]    The defined surface  22  may be generally planar or generally curved. The defined surface  22  may form a plane angle greater than zero with respect to the substrate surface  12 . The plane angle may be between 0 and 90 degrees, for example between 10 and 80 degrees, or between 30 and 60 degrees, or between 40 and 50 degrees, or 45 degrees. As shown schematically in  FIG. 4 a   , a plane angle of 45 degrees may be used to redirect an input beam of light  40  at an angle of 90 degrees. For example, this redirection may be a result of the input beam of light  40  being directly reflected by the defined surface  22  (or a coating on the surface  22 ) and/or internally reflected by the optic component  20 . As depicted in  FIGS. 1 a , 1 b   ,  2   a,  and  3   a,  for an input beam of light  40  to be internally reflected, the input beam of light would enter the substrate  10  from below before striking the defined surface  22  (i.e., for internal reflection, the defined surface  22  is opposite the side of light entry). 
         [0048]    As shown schematically in  FIGS. 4 a  and 4 b   , a pair of optic components  20   a,    20   b  may be separated by an embedded waveguide  25  such that an input beam of light  40  may reflect off an input optic component  20   a,  traverse the embedded waveguide  25 , and traverse the output optic component  20   b  as an output beam of light  42 . As shown schematically in  FIG. 4 b   , the embedded waveguide may comprise a waveguide splitter  27 , such as a 1×2 Y-branched waveguide splitter, that splits the input beam of light  40  into two or more output beams of light  42 ,  42 .  FIG. 5  shows a schematic example of a Y-branched 1×2 waveguide splitter  27 , assuming a single input beam of light  40  is entering the waveguide splitter  27  from the left as depicted and exiting as two output beams of light  42 ,  42  from the right as depicted; or a Y-branched 2×1 wavelength coupler, assuming two input beams of light  40 ,  40  are entering from the right as depicted and exiting as a single output beam of light  42  from the left as depicted. 
         [0049]    As shown schematically in  FIG. 6 , an opto-electronic device  50  may be mounted on a substrate  10 . The opto-electronic device  50  may be configured to transmit or receive light. As depicted, the opto-electronic device  50  is vertically mounted, although this is optional. The opto-electronic device  50  may comprise an optic fiber  52 . 
         [0050]      FIGS. 7 a , 7 b , and 7 c    represent guided-mode images of light from a waveguide. The x- and y-axes represent distances. In  FIG. 7 a   , the guided-mode image comes from light that has not interacted with an optic component  20 . In  FIG. 7 b   , the guided-mode image comes from light that has been reflected off a defined surface  22  of an optic component  20  (here, a mirror), where the optic component  20  has a rougher surface texture, similar to the surface depicted in  FIGS. 2 a  and 2 b   . In  FIG. 7 c   , the guided-mode image comes from light that has been reflected off a defined surface  22  of an optic component  20  (here, a mirror), where the optic component  20  has a smoother surface texture, similar to the surface depicted in  FIGS. 3 a    and  3   b.    
         [0051]    While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the claims.