Modular optical waveguide structure

Abstract: A method for making a modular optical waveguide (100) including a plurality of optical modules (102,103,104,105) with each optical module having at least a core region (101) that is surrounded by a cladding region (111,112). A first groove 114 and a second groove 116 are disposed into cladding region (111,112), thereby separating the optical modules (102,103,104,105). Use: Optical waveguide array connectors.

Description: Background of the Invention This invention relates, in general, to fabrication of optical devices and, more particularly, to manufacturing and fabrication of optical waveguides. This application is related to US-A-5 265 184, published on Nov. 23, 1993. At present, optical waveguides are made in a variety of methods, such as photolithography, diffusion, ion implantation, or a combination of any of the above. Generally, these methods used for manufacturing waveguides are complex, inefficient, and are generally not suitable for high volume manufacturing. However, as use of optical waveguides increase, a need for a fabrication method and a structure that allows for efficient and cost effective manufacturing will be required. Additionally, use of conventional methods for manufacturing waveguides do not provide sufficient flexibility for manufacturing multiple waveguides or modular waveguides, thereby making waveguides difficult to assimilate into standard electronic circuits and electronic components. As a result, these inflexible conventional methods limit use of waveguides for interconnection applications in standard electronic equipment, thus use of waveguides in high volume applications is severely curtailed. Further, conventional methods for manufacturing waveguides required individual processing that is achieved by hand. Processing that is achieved by hand injects many problems into manufacturing, such as being extremely labor intensive, costly, accuracy of workmanship that result in waveguides not being allowed to be manufactured in high volume. Moreover, individual fabrication of waveguides do not readily lend itself to automated manufacturing, thus causing limited use of waveguides in electronic products. It can be readily seen that conventional methods for manufacturing waveguides have severe limitations. Also, it is evident that conventional methods for manufacturing waveguides are not only ineffective, expensive, and complex, but also do not lend themselves to high volume manufacturing. Therefore, a method for manufacturing waveguides in an automatic effective manner would be highly desirable. US-A-5 136 678 discloses an optical wave guide array comprising a plurality of cores embedded in a clad substrate and covered by a covering clad portion. Summary of the Invention It is an object of the present invention to provide an optical waveguide structure which is formed by a plurality of optical waveguide modules. This object is solved, according to the invention, with the features of claim 1. Brief Description of the Drawing The sole FIGURE is a simplified enlarged partial perspective view of a modular optical waveguide. Detailed Description of the Drawing The sole FIGURE is an enlarged simplified partial perspective view of a modular optical waveguide 100. Modular optical waveguide 100 includes individual optical waveguide modules 102, 103, 104, and 105. Each optical waveguide module 102, 103, 104, and 105 is fabricated with at least a core region that is surrounded by a cladding region that forms a first surface 117 and a second surface 118 opposite to each other. However, in a preferred embodiment of the present invention, a plurality of core regions 101 is fabricated within each optical waveguide module 102, 103, 104, 104, or 105. Core regions 101 are surrounded by cladding regions 111 and 112 that form first surface 117 and second surface 118. However, it should be noted that cladding regions 111 and 112 are capable of being formed as a single cladding regions that surrounds core region 101, thus cladding regions 111 and 112 do not have to be made as two pieces. Generally, both core regions 101 and cladding regions 111 and 112 are made of a hard optical transparent polymer, wherein core regions 101 have a higher refractive index than do cladding regions 111 and 112, thus allowing for efficient light confinement, efficient light transmission, and efficient internal reflection through core region 101. Commonly, there is a refractive index difference of at least 0.01 between core regions 101 and cladding regions 111 and 112. In addition, cladding regions 111 and 112 are capable of being made of a translucent material while maintaining an appropriate refractive index as described hereinabove. The translucent materials generally are made by an addition of fillers, such as silicas, silicates, or the like. Addition of these filler materials to the polymer material provides structural benefits, such as hardness, strength, rigidity, lowering the coefficient of expansion, durability to temperature cycling, and the like. In the present invention, modular optical waveguide 100 is fabricated with any suitable number of individual optical waveguide modules, such as optical waveguide modules 102, 103, 104, and 105, that are detachablely connected by grooves 114 and 116, thereby providing ability to generate any desirable length from modular optical waveguide 100. Typically, modular optical waveguide 100 is formed in long (continuous) lengths so as to facilitate use of modular optical waveguide 100 in robotic or automated manufacturing of many versions of different modular genres. For example, with modular optical waveguide 100 being formed with forty optical waveguide modules. Modular optical waveguide 100 is loaded into a robotically controlled manufacturing system (not shown). Via a computer (not shown) that determines the desired length and that directs the robotically controlled manufacturing system, a robotic arm (not shown) cleaves modular optical waveguide 100 through grooves 114 and 116 to the desired length. The desired length is then placed onto a substrate 130 by the robotically controlled manufacturing system. However, a second substrate (not shown) corresponding to a different version of a different modular genre may require a different desired length from that of substrate 130. In response, the robotic arm simply cleaves a subsequent desired length from remaining portion of modular optical waveguide 100 to the desired length of the second substrate and places the desired length onto the second substrate. In the present invention, modular waveguide 100 is made with indents or grooves 116 in surface 117 and with indents or grooves 114 in surface 118 that separate individual optical waveguide modules, such as optical waveguide modules 102, 103, 104, and 105. Further, grooves 114 and 116 traverse across width 128 of modular optical waveguide 100 such that grooves 114 and 116 are aligned and parallel. While grooves 114 and 116 are shown as V-grooves, other geometric configurations are capable of being made to form grooves 114 and 116, such as squared-off channels, U-grooves, beveled surfaces, or the like. In addition, grooves 114 and 116 are capable of being made such that other geometric designs (not shown) are capable of being placed into grooves 114 and 116. Placement of these geometric designs changes structural integrity of grooves 114 and 116, thereby increasing or decreasing grooves 114 and 116 ability to cleave or brake. More specifically grooves 116 and 114 are made using a variety of fabrication methods, such as milling, chemical etching, molding, or the like. However, in a preferred embodiment of the present invention, grooves 116 and 114 are molded during fabrication of cladding regions 111 and 112 of modular waveguide 100 and are subsequently joined to form modular waveguide 100. Alignment of cladding regions 111 and 112 prior to joining is accomplished by an automatic system such as a robotic arm (not shown) with machine vision. However, it should be noted that other alignment systems are capable of being used as well. By molding grooves 114 and 116 during the fabrication of optical modular waveguide 100, an accurate and repeatable process is achieved which allows for automated manufacturing of modular waveguide 100, thus reducing cost and increasing accuracy of optical modular waveguide 100. Further, it should be understood that molding alignment guides 121 during the fabrication of cladding region 112 enables alignment guides 121 to take advantage of the accuracy and the repeatability of the molding process. Moreover, by molding long lengths of modular waveguide 100 and cleaving the required number of modules, a center to center spacing of alignment guides 121 is effectively and easily maintained, thus ensuring that connector cables 140 are easily inserted into alignment guides 121. Grooves 114 and 116 are made with a specific depth illustrated by arrows 122 and 123, respectively. However, the specific depth of grooves of 114 and 116 is dependent upon several parameters, such as relative thicknesses of cladding regions 111 and 112, hardness of the material forming cladding regions 111 and 112, and the like. Therefore, it should be noted that depending upon choice of materials, design of modular optical waveguide 100, and manner of cleaving depth of grooves 114 and 116 are adjusted accordingly. However, a general ratio that ranges from 4:1 to 6:1 relates total depth of grooves 114 and 115 to thickness 126 that can be used for most materials used for making cladding regions 111 and 112. By way of example only, with cladding regions 111 and 112 each being approximately one millimeter in thickness as illustrated by arrows 124 and 125 respectively. In accordance with the above stated ratio, thickness 126 is capable of ranging from 0.5 millimeter to 0.33 millimeter, thus depths 123 and 122 of grooves 114 and 116 if evenly split range from 1.5 millimeter to 1.67 millimeter. However, it should be understood that the total depth does not have to be evenly split between cladding regions 111 and 112. Uneven splits of the total depth are possible, as well as having the total depth being located in only one cladding region. In addition, it should be understood that cleaving along grooves 114 and 116 can be modified by a variety of structures as described hereinabove, thus enabling further customization of structural element so as to provide proper material characteristics for each specific application. By now it should be appreciated that an article and method for making modular optical waveguides have been described. The method allows for a highly manufactureable and cost effective method that provides accurate cleaving of desirable lengths of modular optical waveguides effectively and repeatability. Further, this method allows for automated processing that further reduces cost.

Claims: A detachable modular optical waveguide structure comprising a multitude of core channels (101) surrounded by a common cladding region (111, 112), wherein the cladding region (111, 112) has first and second surfaces (117, 118) either side of said core channels, said surfaces being parallel to one another; a plurality of grooves (116) equidistantly spaced in the first surface (117) of the cladding region (111, 112) segmenting said waveguide structure into a plurality of repeating optical waveguide modules (102, 103, 104, 105) and a plurality of grooves (114) equidistantly spaced in the second surface (118), wherein the plurality of grooves (114) in the second surface (118) are aligned to the plurality of grooves (116) in the first surface (117), so as to enable a desired number of waveguide modules to be detached from said optical waveguide structure. A detachable modular optical waveguide structure as claimed in claim 1 wherein the optical waveguide modules (102, 103, 104, 105) are molded. A detachable modular optical waveguide structure as claimed in claim 1 wherein plurality of grooves (116, 114) on the first and second surface (117, 118) are molded. A detachable modular optical waveguide structure as claimed in claim 1 wherein the plurality of grooves (116, 114) on the first and second surfaces (117,118) are machined.

Inventors: BLAIR THOMAS H, HARTMAN DAVIS, LEBBY MICHAEL S, BLAIR, THOMAS H., HARTMAN, DAVIS, LEBBY, MICHAEL S.
Applicants: MOTOROLA INC, MOTOROLA, INC.
Application year: 1993
Main classification: G02B6
IPC codes: G02B6