Patent Publication Number: US-8542961-B2

Title: Optical beam couplers and splitters

Description:
BACKGROUND 
     The present disclosure relates generally to optical beam couplers and splitters. 
     Since the inception of microelectronics, a consistent trend has been toward the development of optoelectronic circuits, such as optical interconnects. This may be due, at least in part, to the fact that optoelectronic circuits may offer advantages over typical electronic circuits, such as, for example, a much larger bandwidth (by many orders of magnitude). Such optoelectronic circuits often involve the transmission of optical signals, and the interconversion of such optical signals into electronic signals. In some instances, performing optical signal transmission involves a waveguide. Optical wave guides are commonly made with glass or polymers. Extraction of a fraction of the guided signal with these solid wave guides typically requires complicated tapping structures. Some optical waveguides are hollow metal structures. Optical signals propagate in air through such structures, and, as such, stringent alignment and collimation are required for proper signal transmission. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features and advantages of embodiments of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to the same or similar, though perhaps not identical, components. For the sake of brevity, reference numerals having a previously described function may or may not be described in connection with subsequent drawings in which they appear. 
         FIG. 1  is a flow diagram depicting an embodiment of a method for forming an embodiment of a beam coupler and splitter; 
         FIGS. 2A through 2C  together depict a schematic flow diagram of an embodiment of the method for forming an embodiment of the beam coupler and splitter; 
         FIGS. 2A ,  2 B and  2 D together depict a schematic flow diagram of another embodiment of the method for forming another embodiment of the beam coupler and splitter; 
         FIGS. 2A ,  2 B and  2 E together depict a schematic flow diagram of another embodiment of the method for forming still another embodiment of the beam coupler and splitter; 
         FIGS. 2A ,  2 B and  2 F together depict a schematic flow diagram of another embodiment of the method for forming yet another embodiment of the beam coupler and splitter; 
         FIGS. 3A and 3B  together depict a schematic flow diagram of an embodiment of the method for forming another embodiment of the beam coupler and splitter including compound bevels; 
         FIG. 4A  is a schematic diagram of another embodiment of the beam coupler and splitter shown in  FIG. 2F  with an angled bend; 
         FIG. 4B  is a schematic diagram of still another embodiment of the beam coupler and splitter shown in  FIG. 2F  with a curved bend; 
         FIG. 5A  is a schematic diagram of another embodiment of the beam coupler and splitter shown in  FIG. 2D  with an angled bend; 
         FIG. 5B  is a schematic diagram of another embodiment of the beam coupler and splitter shown in  FIG. 2D  with a curved bend; 
         FIG. 6  is a schematic cutaway view of an embodiment of a symmetrical beam coupler and splitter, in which ends of the waveguides are rounded; 
         FIG. 7  is a schematic diagram of an embodiment of a symmetrical module including an embodiment of the beam coupler and splitter similar to that shown in  FIG. 4 ; 
         FIG. 8  is a schematic diagram depicting an embodiment of a plurality of waveguides cascaded together; 
         FIG. 9A  is a schematic diagram depicting another embodiment of a plurality of waveguides cascaded together; 
         FIG. 9B  is a schematic diagram depicting still another embodiment of a plurality of waveguides cascaded together; 
         FIG. 9C  is a schematic diagram depicting yet another embodiment of a plurality of waveguides cascaded together; 
         FIG. 10  is a schematic diagram of a system including a plurality of beam couplers and splitters separated via cladding layers; and 
         FIG. 11  is another embodiment of a beam coupler and splitter. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the beam coupler and splitter disclosed herein include various waveguides which are configured to enable flexible topographical arrangements for the layout and routing of signal paths. The coupling ratio of the beam coupler and splitter may advantageously be adjusted dynamically (e.g., out in the field) or set to a predetermined fixed ratio. In the embodiments disclosed herein, the coupling ratio is independent of the polarization of the optical signal, and in some instances, coupling/splitting results without significant attenuation of the optical signal. 
     Referring now to  FIG. 1 , an embodiment of the method for forming an embodiment of the beam coupler and splitter disclosed herein is depicted. Generally, the method includes forming a bevel and a bend in a first waveguide, as shown at reference numeral  100 ; positioning a second waveguide such that a complementarily shaped bevel of the second waveguide is adjacent to at least a portion of the first waveguide bevel, as shown at reference numeral  102 ; and adjusting the coupling ratio between the first and second waveguides, as shown at reference numeral  104 . It is to be understood that this method will be discussed further hereinbelow in reference to  FIGS. 2A through 2G ,  3 A and  3 B, and  4 - 10 .  FIG. 11  depicts another embodiment of a beam coupler and splitter, and the method of forming such embodiment will be discussed in reference to  FIG. 11 . 
       FIGS. 2A and 2B  generally depict the formation of the first waveguide  12  with a bend and a bevel  14 . The bend is generally opposed to the bevel  14 , and the bevel  14  is symmetrical to the input port I and output port O sections of the waveguide  12 . The bevel  14  is configured to totally internally reflect light incident thereon, so that light from the input port I is redirected toward the output port O (except at areas where the device is otherwise configured to transmit light through the bevel  14 , as discussed in various embodiments hereinbelow). When the first waveguide  12  is linear, it is to be understood that a bend may be formed by coupling another waveguide that provides a path for light incident on and reflected off of the bevel  14  (see, for example,  FIG. 9B ). 
     As shown in  FIG. 2A , the first waveguide  12  may be formed by adhering two fibers F 1 , F 2  together. Generally, the fibers F 1 , F 2  are formed of the same material having a desirable refractive index, and are adhered together via an index matching adhesive (e.g., glue). In a non-limiting example, the fibers F 1 , F 2  forming waveguide  12  are glass, polymeric material(s) (e.g., polycarbonate, polyamide, acrylics, etc.), silicon, or another like material. The diameter of each of the fibers F 1 , F 2  ranges from about 20 microns to about 1000 microns. In one embodiment, the fibers F 1 , F 2  may be adhered so that the waveguide  12  exhibits the desirable bend. In another embodiment, a single fiber may be physically bent to a desirable radius of curvature. It is to be understood that the bend may be at any desirable angle θ b  (as shown in  FIG. 2A ) or at any desirable radius of curvature, each of which depends, at least in part, on the desirable path for the light beams. The bend in  FIG. 2A  is shown at 90° and a radius of curvature of 0. In other embodiments, the radius of curvature is larger than zero, and the bending is gradual and continuous (see, for example,  FIGS. 4B and 5B , as opposed to the abrupt angle θ b  shown in  FIG. 2A ). 
     Once the fibers F 1 , F 2  are adhered in a desirable manner, a bevel  14  is formed in the first waveguide  12 . In a non-limiting example, the bevel  14  is cut and polished. In another non-limiting example, a mold having the desirable shape (e.g., that shown in  FIG. 2B ) may be used to form the bend and the bevel  14  of the waveguide  12 . In still other techniques, lithography is used to form the waveguide  12 . The surface of the bevel  14  may be flat or curved. As previously mentioned, light incident on at least some of the bevel  14  undergoes total internal reflection; as such, at least one portion of the bevel  14  is configured at an angle θ b1  (with respect to the axis A 1 ) that is less than 90°−critical angle (which is defined by arcsin*(n 2 /n 1 ), wherein n 2  is the refractive index of the less dense medium (e.g., air reflective coating) and n 1  is the refractive index of the denser medium (e.g., the waveguide  12 )). For typical waveguide  12  materials (see above), the angle θ b1  is 45° or less. As shown in  FIG. 2B , the bevel  14  is at a 45° angle. 
     As shown in  FIGS. 2C through 2F , the first waveguide  12  is coupled in some manner with a second waveguide  16 . In all of the embodiments described in reference to  FIGS. 2C through 2F , the second waveguide  16  includes a bevel  18  that is complementarily shaped to the first waveguide bevel  14 , and the second waveguide bevel  18  is positioned adjacent to at least a portion of the first waveguide bevel  14 . As shown in  FIGS. 2C through 2F , the phrase “positioned adjacent to” includes one bevel  14  contacting the other bevel  18  directly or such that a material (e.g., a reflector, air, etc.) is positioned therebetween. 
     It is to be understood that all embodiments of the second waveguide  16  (including bevel  18 ) disclosed herein may be formed via the same method described hereinabove for forming all of the embodiments of the first waveguide  12  (including bevel  14 ) disclosed herein. As discussed further hereinbelow, any embodiment of the second waveguide  16  may be formed of the same or a different material than the first waveguide  12 , and thus may have the same or a different refractive index than the first waveguide  12 . Generally, the second waveguide  16  is formed of one or more fibers, depending, at least in part on the configuration of the waveguide  16 . Still further, in some instances, the second waveguide  16  is a different shape than the first waveguide  12 , and in other instances, the second waveguide  16  is symmetrical to the first waveguide  12 . 
     In some instances, the first and/or second waveguides  12 ,  16  respectively may be composed of holey or microstructured fibers. Such holey fibers have a substantially regular arrangement of air holes extending along the length of the fiber to act as a cladding layer. The core is generally formed by a solid region in the center of the substantially regular arrangement of air holes, or by an additional air hole in the center of the substantially regular arrangement of air holes. The effective refractive index of such fibers is determined by the density of the holes. As such, the holes may be arranged to change the effective index of the waveguides  12  and/or  16 . The core of holey fibers will generally have a lower density of holes than the cladding layer, and thus the effective index of the core is generally higher than that of the cladding. 
     In each of the embodiments, the ratio (i.e., coupling or splitting ratio, R=r/t) of reflected light r to transmitted light t may be varied depending upon the coupling technique utilized to couple the waveguides  12 ,  16 . It is to be understood that adjusting the ratio may be performed dynamically (e.g., in the field), or may be accomplished such that the beam coupler and splitter is manufactured with a fixed coupling ratio. In the Figures, “i” represents the light beams input into the waveguide  12 . 
     In the embodiments disclosed herein, the refractive indices of the waveguides  12 ,  16  are the same or about the same. The indices of the waveguides  12 ,  16  should be within the range of sin(90−θ b1 )&lt;n 2 /n 1 . In such instances, each of the waveguides  12 ,  16  may be selected from glass, polymeric material(s) (e.g., polycarbonate, polyamide, acrylics, etc.), silicon, or another like material. In order to achieve the desirable coupling ratio when the materials of the waveguides  12 ,  16  are the same, many different techniques may be utilized. Such techniques are described in reference to  FIGS. 2C-2F  and  FIGS. 3A and 3B . 
     In  FIG. 2C , the coupling ratio of the beam coupler and splitter  10 ′ is adjusted by establishing an at least partially reflective coating  20  between the bevels  14 ,  18 . The percentage of reflectivity and the pattern in which the at least partially reflective coating  20  is established depend, at least in part, on the desirable beam splitting properties at the interface between the bevels  14 ,  18 . In some instances, the coating  20  is partially reflective (i.e., less than 100% reflective) and is established on the entire interface between the bevels  14 ,  18 . In other instances, the coating  20  is 100% reflective, and is established on portions of the interface between the bevels  14 ,  18  (e.g., in a dotted, striped or other like pattern). In still other instances, some portions of the coating  20  are 100% reflective, while other portions of the coating  20  are less than 100% reflective. Light beams contacting the reflective portions of the coating  20  will be redirected (e.g., into the upper portion of the first waveguide  12 ), while light beams contacting the less or non-reflective portions of the coating  20 , or those areas between the bevels  14 ,  18  not including the coating  20 , will continue to pass through to the waveguide  16 . 
     As a non-limiting example, if it is desirable to have 75% of the light beams transmitted through to the second waveguide  16  and 25% of the light beams reflected into the upper portion of the first waveguide  12 , than a 100% reflective coating  20  may be established on 25% of one of the bevels  14 ,  18  before the bevels  14 ,  18  are adhered together. 
     Non-limiting examples of suitable materials for the at least partially reflective coating  20  include silver, aluminum, or another material that is a reflector of the selected wavelength of light. The at least partially reflective coating  20  may be established on either or both of the bevel surfaces prior to adhering the bevels  14 ,  18  together. Non-limiting examples of suitable techniques for establishing the coating  20  are thermal or e-beam evaporation, sputtering or CVD/PVD growth. 
     It is to be further understood that the thickness of the at least partially reflective coating  20  may also be changed to adjust the coupling ratio. The percentage of reflection is determined by the thickness of the coating  20 . For example, a 0.01 μm thick coating of aluminum would be partially reflective, while a 1 μm thick coating of aluminum would be 100% reflective. As such, the desired coupling ratio may be controlled by the thickness of the coating  20 . In some instances, multiple layers of materials having different indices of refraction may also be used to achieve partial reflection. The reflection of such a multi-layer coating would be polarization dependent, and thus may be less desirable. 
     Referring now to  FIG. 2D , in this embodiment of the beam coupler and splitter  10 ″, the coupling ratio is adjustable by offsetting the second waveguide bevel  18  from the first waveguide bevel  14 . As depicted, light beams that are incident on the bevel  14  that is not adjacent to waveguide  16  experience total internal reflection and are rerouted within the waveguide  12 . In this embodiment, since the waveguides  12 ,  16  have the same refractive index, those light beams incident on the interface at which the bevels  14 ,  18  are in direct contact are transmitted through to the waveguide  16 . As the offset increases, the ratio of reflected light to transmitted light increases. 
       FIG. 2E  depicts still another embodiment of how the coupling ratio of the beam coupler and splitter  10 ′″ may be adjusted. In this embodiment, a gap G is formed between the bevels  12 ,  16 . When the gap G thickness is less than 1 wavelength, the light beams will be transmitted. In some instances, the gap G is constant throughout the interface between bevels  12 ,  16 . In other instances, the gap G may have varying thicknesses along the length of the bevels  12 ,  16  so that a desirable percentage of the light beams is reflected and transmitted. It is to be understood that when the gap G is larger than about 1 wavelength, the first waveguide bevel  14  is adjacent to air. In such an example, total internal reflection occurs at the bevel  14 , and thus there is no coupling between the waveguides  12 ,  16 . 
     The embodiments of  FIGS. 2C through 2E  illustrate a substantially linear second waveguide  16 .  FIG. 2F  illustrates another example of the second waveguide  16 ′. As depicted, this embodiment of the second waveguide  16 ′ includes a bend, and is symmetrical to the first waveguide  12 . It is to be understood that the shapes, bends, and/or angles of the waveguides  12 ,  16 ′ in this Figure are illustrative and not limiting. Furthermore, since the materials for the waveguides  12 ,  16 ,  16 ′ are relatively flexible, the waveguides  12 ,  16 ,  16 ′ may be configured with other shapes (e.g., including curves, see  FIG. 10 ). 
     The configuration of the beam coupler and splitter  10  of  FIG. 2F  may be used to couple and split light in various ways. Light beams (labeled i and i 1 ) may be input via either one of the input ports I or via both of the input ports I of the waveguides  12 ,  16 ′. When both input ports I are utilized, different information/signal/modulation may be encoded in the respective light beam(s) entering input ports I of waveguides  12 ,  16 ′. The signals are combined by the splitter/combiner/coupler  10  in  FIG. 2F  and are routed to different destinations through the output ports O of the waveguides  12 ,  16 ′. The light entering the input ports I may be time multiplexed or of different wavelengths to allow separation of the combined signals at the output ports O. It is to be understood that the input ports I and output ports O of the embodiment shown in  FIG. 2F  may be reversed, thereby reversing the path of the light beams through the beam coupler and splitter  10 . It is to be further understood that any one or more of the techniques for adjusting the coupling ratio described in conjunction with  FIGS. 2C-2E  may be implemented in the embodiment shown in  FIG. 2F . 
     Referring now to  FIGS. 3A and 3B , other embodiments of the waveguide  12 ′,  16 ″ are depicted. The embodiments shown in  FIGS. 2A-2F  illustrate single bevels  14 ,  18 , while the embodiments shown in  FIGS. 3A-3B  illustrate compound bevels  14 ′,  18 ′. Generally, the adherence of the compound bevels  14 ′,  18 ′ (shown in  FIG. 3B ) results in the formation of gaps G that are large (e.g., greater than 1 wavelength) and constant such that light incident on the sub-bevels  24 ,  24 ′ adjacent to the gaps G is totally internally reflected into waveguide  12 ′. However, light that is incident on the contact surfaces is 100% transmitted through the waveguides  12 ′,  16 ″. The ratio of the contacting area and the gap G area (and thus the coupling ratio) is controlled by the asymmetry of the waveguides  12 ′,  16 ″. The compound bevel  14 ′ of the first waveguide  12 ″ includes sub-bevels  24 ,  24 ′. Similarly, the compound bevel  18 ′ of the second waveguide  16 ″ includes sub-bevels  28 ,  28 ′. The sub-bevels  24 ,  24 ′ and  28 ,  28 ′, of each waveguide  12 ′,  16 ″ are separated via a contact surface that is perpendicular to an axis A 1 , A 2  of the respective waveguides  12 ′,  16 ″. The dimensions of the first waveguide sub-bevel  24  correspond with the dimensions of the second waveguide sub-bevel  28 ′, and dimensions of the first waveguide sub-bevel  24 ′ correspond with the dimensions of the second waveguide sub-bevel  28 . When the contact surfaces of the bevels  12 ′,  16 ″ are in direct contact, these dimensions form the gaps G between sub-bevels  24  and  28  and  24 ′ and  28 ′. In this non-limiting example, the gaps G are formed without offset of the compound bevels  14 ′,  18 ′. 
     It is to be understood that any of the coupling ratio adjustment techniques disclosed herein may be incorporated together in the same beam coupler and splitter. 
     Referring now to  FIGS. 4A and 5A , still other examples of the beam coupler and splitters of  FIGS. 2F and 2D  are shown. The examples in  FIGS. 4A and 5A  illustrate that the waveguides  12 ,  16 ,  16 ′ may be configured with bend angles θ b  other than 90°, and that the bevels  14 ,  18  may be configured at angles θ b1  other than 45°. It is believed that smaller bevel  14 ,  18  angles θ b1  enable the beam coupler and splitter  10 ,  10 ′,  10 ″,  10 ′″ to be used in situations where the difference in the index of refraction between the waveguides  12 ,  16 ,  16 ′ and the surrounding material (e.g., clad) is small. A larger radius of curvature also enables different physical configurations to be obtained. As shown in  FIGS. 4B and 5B , the bends of the waveguides  12 ,  16 ,  16 ′ may be continuous and curved instead of abrupt (as shown in  FIGS. 4A and 5A ). 
       FIG. 6  is an example of still another embodiment of the beam coupler and splitter  10 . In this embodiment, the ends of the fibers forming the waveguides  12 ,  16 ′ are rounded via a reflow technique, heating technique, or other suitable technique. The rounded ends form self-aligned lenses to couple light beams in and/or out of the beam coupler and splitter  10 . It is to be understood that rounded ends may be included on any of the embodiments disclosed herein. 
       FIG. 7  illustrates a non-limiting example of a symmetrical module  30  including the embodiment of the beam coupler and splitter  10  shown in  FIG. 4 . In this module  30 , the length of the waveguides  12 ,  16 ′ is increased, and connectors  22  are operatively connected to the ends of the waveguides  12 ,  16 ′. It is to be understood that the connectors  22  are generally used to connect the waveguides  12 ,  16 ′ to other waveguides  12 ,  12 ′,  16 ,  16 ′,  16 ″ to create a network. A connector  22  is a physical assembly that allows the ends of the fibers  12 ,  16 ′ to be accurately positioned. Such connectors  22  may be particularly desirable for embodiments in which multiple waveguides (with multiple input ports/output ports) are aligned (see  FIG. 10 ). The connectors  22  may also include physical guides to allow coupling with a matching fiber ribbon. Some connectors  22  include lenses which focus light beams between adjacent waveguides. 
     In the embodiment shown in  FIG. 7 , the input and output of the light beams may be inverted, as desired.  FIG. 7  also depicts a mechanical enclosure  25  surrounding the beam coupler and splitter  10 . As a non-limiting example, such an enclosure  25  may be a box with air therein. 
     In any of the embodiments disclosed herein, a clad material (not shown) may be over the exterior surface of the optical fibers (i.e., waveguides  12 ,  16 ′) of the beam coupler and splitter  10 . Generally, the clad material is removed at the region where the bevels  14 ,  18  are formed to facilitate the splitting of the beam. Such a clad material generally has an index of refraction that is lower than the index of refraction of the waveguides  12 ,  16 ′. Non-limiting examples of suitable clad materials include fluorocarbon resins (such as TEFLON® from Dupont), silicon, insulating materials, or the like. The clad material may be deposited via chemical vapor deposition (CVD), ion implementation of a dopant, dipping, or other like processes. The cladding materials may also be spun on, cured, and hardened when the temperature reaches the glass transition temperature. 
     Referring now to  FIG. 8 , a plurality of waveguides  12 ,  16 ,  34  are coupled together to form a bus  26  (through which transmitted light beams travel) with multiple taps  29  (through which reflected light beams travel). First and second waveguides  12 ,  16  are coupled together via one of the methods disclosed hereinabove. In this embodiment, the second waveguide  16  is configured with a second bevel  32  that couples with an additional (e.g., third) waveguide  34  having a complementarily shaped bevel  36 . The additional waveguide  34  is also configured with a second bevel  38  that is coupled to a complementarily shaped bevel  36 ′ of still another (e.g., fourth) waveguide  34 ′. In this particular non-limiting example, a fifth waveguide  34 ″ includes a bevel  36 ″ that is complementarily shaped to a second bevel  38 ′ of the fourth waveguide  34 ′. While five waveguides  12 ,  16 ,  34 ,  34 ′,  34 ″ are shown in  FIG. 8 , it is to be understood that any number of waveguides may be coupled together to achieve desirable light paths. 
     Also as shown in  FIG. 8 , each of the additional waveguides  34 ,  34 ′,  34 ″ is offset from a directly adjacent waveguide. Such offsets alter the coupling ratios of the adjacent waveguides, as described hereinabove. It is to be understood that any of the other methods disclosed hereinabove may be utilized to alter the respective coupling ratios. 
     In one embodiment, the waveguides  12 ,  16 ,  34 ,  34 ′,  34 ″ are formed of the same material and thus have the same index of refraction. In this embodiment, an at least partially reflective coating  20  (not shown in this Figure) formed via the techniques described hereinabove may be established between bevels that are not offset or separated via a gap G. It is to be understood, however, that the waveguides  12 ,  16 ,  34 ,  34 ′,  34 ″ may have their respective coupling ratios altered via any of the other techniques described herein (or via a combination of such techniques). 
       FIG. 9A  illustrates yet another embodiment of a plurality of waveguides  12 ,  16  cascaded together. In this embodiment, an additional waveguide  40  is established on at least a portion of the first and second waveguides  12 ,  16 . The additional waveguide  40  creates a bend for the first waveguide  12 , such that light totally internally reflected therein is transmitted to the waveguide  40 . The additional waveguide  40  may be adhered to the waveguides  12 ,  16  via an index matching adhesive material (e.g., glue) when the waveguides  12 ,  16 ,  40  have the same refractive index. 
     In this embodiment, the bevels  14 ,  18  have the at least partially reflective coating formed via the techniques described hereinabove established thereon in order to split the light beams per a desirable coupling ratio. It is to be understood, however, that the coupling ratio may be achieved via the other methods disclosed herein (e.g., offset, formation of gap G, compound bevel  14 ′,  18 ′, combinations thereof, etc.). 
     Light beams that are reflected off of the at least partially reflective coating  20  are directed toward the surface S that is configured to totally internally reflect any light beams incident thereon. The internally reflected light beams are redirected 90° such that they travel out of the additional waveguide  40 . 
     As shown in  FIG. 9A , the other surface S 2  of the additional waveguide  40  may be adhered to yet another waveguide  42  to further direct the light beams in a desirable manner. Generally, the surface S 2  and the complementarily shaped surface of the waveguide  42  are configured so that light is transmitted therethrough. The waveguide  42  has a bevel  46  that is complementarily shaped to a bevel  48  of a waveguide  44  adhered thereto. In this non-limiting example, the bevels  46 ,  48  have the at least partially reflective coating  20  established therebetween in order to split the light beams according to a predetermined coupling ratio. Another additional waveguide  40 ′ is established on at least a portion of the waveguides  46 ,  48 . This additional waveguide  40 ′ may be adhered to the waveguides  46 ,  48  via an index matching adhesive material (e.g., glue), as generally the waveguides  46 ,  48 ,  40 ′ have the same refractive index. 
     Light beams that are reflected off of the at least partially reflective coating  20  between the bevels  46 ,  48  are directed toward the surface S′ that is configured to totally internally reflect any light beams incident thereon. The internally reflected light beams are redirected 90° such that they travel out of the additional waveguide  40 ′. 
     As shown in  FIG. 9A , a similar stack of waveguides  42 ′,  44 ′ and  40 ″ may be operatively coupled to the other waveguides  12 ,  16 ,  40 ,  42 ,  44 ,  40 ′ by adhering the surface S 2 ′ of waveguide  40 ′ to a complementarily shaped surface of the waveguide  42 ′. The remainder of the waveguides  44 ′,  40 ″ may be configured and positioned as previously described for waveguides  16 ,  40 ,  44 ,  40 ′. Such stacks may be repeated as many times as is suitable to achieve desirable light paths. 
     As shown in phantom, a cladding layer  50  may also be established between the additional waveguides  40 ,  40 ′,  40 ″ and the waveguides  12 ,  16 ,  42 ,  44 ,  42 ′,  44 ′ upon which they are established. The reflected light beams are able to travel through such cladding layers  50 . In some instances, the cladding layer  50  is established between the waveguides  16 ,  40 ,  44 ,  40 ′, and  44 ′,  40 ″. 
     As previously mentioned, while the at least partially reflective coating  20  is shown in  FIG. 9A  (and in  FIG. 9B  discussed hereinbelow), it is to be understood that the coupling ratio between adjacent waveguides  12 ,  16 ,  42 ,  44 ,  42 ′,  44 ′ may be achieved via the other methods disclosed herein (e.g., offset, formation of gap G, compound bevel  14 ′,  18 ′, combinations thereof, etc.). 
       FIG. 9B  illustrates a similar embodiment of that shown in  FIG. 9A , except that the waveguides  40  and  40 ′ include a bevel at their respective second surfaces S 2 , S 2 ′ that is complementarily shaped to the bevels  48 ,  48 ′ of the adjacent waveguides  44 ,  44 ′. In this embodiment, waveguides  42 ,  42 ′ are not included. 
       FIG. 9C  illustrates still another embodiment of a plurality of waveguides  12 ,  16 ,  56 ,  56 ′,  58 ,  60  cascaded together. In this embodiment, waveguides  12 ,  16  are coupled in an offset manner, such as that described hereinabove in reference to  FIG. 2D . A third waveguide  56  is positioned on the waveguide  12  (thereby forming a bend for light totally internally reflected from waveguide  12 ). The waveguide  56  itself includes a bend and a surface S (i.e., a bevel) that totally internally reflects the light beams incident thereon. This waveguide  56  may be formed via the method described hereinabove for the waveguide  12 . 
     As depicted, the waveguide  56  may include a second surface S 2  that is coupled to yet another waveguide  58 . While not shown, it is to be understood that the second surface S 2  may also be a bevel, if it is so desired. Additional waveguides, for example, waveguides  60 ,  56 ′, may be coupled in a suitable manner to achieve the desirable path for the light beams. 
     In this embodiment, the waveguides  12 ,  16 ,  58 ,  60  are shown as being offset to achieve the desirable coupling ratio, however, it is to be understood that the coupling ratio between adjacent waveguides  12 ,  16 ,  58 ,  60  may be achieved via the other methods disclosed herein (e.g., at least partially reflective coating  20 , formation of gap G, compound bevel  14 ′,  18 ′, combinations thereof, etc.). 
     Referring now to  FIG. 10 , a non-limiting example of a system  100  including a plurality of beam couplers and splitters  10 ′ is depicted. The beam couplers/splitters  10 ′ form multiple parallel light channels. Each channel of this system  100  includes the first and second waveguides  12 ,  16  having the at least partially reflective coating  20  between the complementary bevels  14 ,  18 , and the additional waveguide  40  positioned to redirect light beams traveling from the bevels  14 ,  18 . While the reflective coating  20  is shown in this embodiment to achieve the desirable coupling ratio, it is to be understood that any of the other adjustments disclosed herein may be made to obtain the desirable coupling ratio. 
     Each channel of the system  100  is separated from an adjacent component  10  or channel via a cladding layer  50 . The cladding layer  50  assists in reducing or eliminating optical crosstalk between the components  10 ′. The cladding layer  50  is generally formed of a material having a lower refractive index than the refractive index of the waveguides  12 ,  16 . As previously mentioned, non-limiting examples of suitable cladding layer materials include fluorocarbon resins (such as TEFLON® from Dupont), silicon, insulating materials, or the like. This cladding layer  50  may be deposited via chemical vapor deposition (CVD), ion implementation of a dopant, dipping, or other like processes. The cladding materials may also be spun on, cured, and hardened when the temperature reaches the glass transition temperature. 
     It is to be understood that each of the couplers/splitters  10 ′ in the system  100  has a light source  52  directing light beams to the respective waveguides  12 . A non-limiting example of such a light source is a vertical-cavity surface-emitting laser (VCSEL). An individual lens  54  (shown in phantom) may also be utilized to direct the light beams from one light source  52  to the corresponding waveguide  12 . The arrows shown in  FIG. 10  illustrate how the light is guided through each of the beam couplers/splitters  10 ′. As depicted, the light of the system  100  is coupled in a parallel manner utilizing the components  10 ′. 
     Also shown in  FIG. 10  is a non-limiting example of how the waveguides (in this example, one of the additional waveguides  40 ) may be configured to have a curved shape. It is believed that since relatively flexible materials (e.g., polymers) may be used to form the waveguides, such alternate shapes may be readily achieved. Such waveguides function similarly to ribbon cables for the transmission of electrical signals. 
     While not shown in the Figures, one or more detectors may be positioned to detect some or all of the light beams exiting the beam couplers and splitters. 
     Referring now to  FIG. 11 , another embodiment of the beam coupler/splitter  1000  is depicted. This embodiment of the beam coupler/splitter  1000  includes a T-shaped waveguide  52  having a single input port I and two output ports O 1 , O 2 . The materials described hereinabove for the other waveguides  12 ,  16 , etc. may be used to form T-shaped waveguide  52 . As one non-limiting example, a first fiber may be adhered to a second fiber to form the T-shaped waveguide  52 . As another non-limiting example, a single fiber may form the T-shaped waveguide  52 . 
     A wedge  54  is formed in the T-shaped waveguide  52  at a position such that the wedge  54  splits light beams entering the T-shaped waveguide  52  via the single input port I in a predetermined manner between the two output ports O 1 , O 2 . Moving the wedge  54  along the axis A 54  will vary the ratio of light beams reflected to the first output O 1  to light beams reflected to the second output O 2 . As an example, if the wedge  54  shown in  FIG. 11  is moved along the axis A 54  toward the output O 1  (but still opposed to the input port I), more light would be directed toward the output O 2 . 
     The angles of the wedge  54  are configured such that total internal reflection occurs. The wedge  54  may be formed in the waveguide  52  via, e.g., molding or lithography techniques. 
     The beam coupler and splitters  10 ,  10 ′,  10 ″,  10 ′″,  1000  disclosed herein may be configured to guide any desirable wavelengths. As such, the terms “light” and “light beams” used herein, are broadly defined to include wavelengths ranging from about 400 nm to about 1500 nm. In some instances, the light refers to electromagnetic radiation with a wavelength near the visible range (400 nm-700 nm). In other instances, the light refers to wavelengths of 850 nm. In still other instances, the light refers to the wavelength commonly used for telecommunications, or 1500 nm. 
     While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.