Abstract:
An optical coupler arrangement which is employed for replicating surface features of diverse types of optical devices. Also disclosed is to a novel method of accurately replicating surface features of optical devices; particularly through the utilization of the novel optical coupler arrangement.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical coupler arrangement which is employed for replicating surface features of diverse types of optical devices. Moreover, the invention is directed to a novel method of accurately replicating surface features of optical devices; particularly through the utilization of the novel optical coupler arrangement. 
   The manufacture of diverse types of optical devices, such as optical couplers, waveguides and related kinds of devices, necessitates the formation of surface features which are intended to receive or mount optical fibers or the likes at a high degree of precision in their placement. The replication methods which are currently employed in producing surface features of optical devices, for instance, such as grooves for the containment of optical fibers, are subject to limitations inasmuch as during replication thereof, frequently encountered are distortions and manufacturing inaccuracies which are potentially caused by the types of manufacturing methods and materials which are presently employed in this technology. For instance, in applying various types of replication methods which are intended adapted to form surface features, such as optic fiber-receiving grooves in substrates, the desired processing precision during replication is adversely affected or even lost due to differences in the materials, thermal variations and surface flaws present in the replication components or masters. 
   Conventional optical connectors and couplers are equipped with fibers which are retained in a captive position within channels or grooves defined between the upper and lower halves of mating substrates. Generally, one of the substrates is provided with a surface which is traversed by parallel grooves, each such groove normally possessing a V-shaped cross-section. These grooves are ordinarily formed by either photolithography and/or chemical etching methods, resultingly necessitating the employment of sophisticated production equipment and tightly controlled chemical processes. Moreover, in implementing successive replications, the different types of materials and wear over time and use of the processing components lead to unacceptably high manufacturing tolerances, adversely affecting the efficacy of any optical device formed by means of such methods. Although the use of masters in replicating patterns or grooving substrates for the positioning of optical fibers or the like is widely known, the current technology in employing the photolithographic and chemical etching processes, through requiring complex arrangements and methods render the manufacture of accurate and widely diverse optical devices expensive and cumbersome. In contrast with the foregoing, the present invention improves upon the currently known replicating arrangements and manufacturing methods for producing optical devices by rendering them simpler and also being less expensive while providing a superior process and higher degree of accuracy in forming grooved or contoured surfaces on the substrate. In that connection, pursuant to the invention there is employed a pressing process adapted to essentially form a master part and a submaster which acts as a mold for the replication of couplers for optical devices. This particular type of arrangement and method of producing replicated couplers for optical devices is not at all disclosed nor suggested in the current state-of-the technology. 
   2. Discussion of the Prior Art 
   Kojima et al. U.S. Pat. No. 6,181,854 B1 describes an optical module which is adapted to be manufactured through the intermediary of transfer molding. The structure produced in forming the optical module is through the use of a molded resin and is limited to a particular single application and which cannot be readily employed to the replication of optical devices pursuant to the invention. This is because as Kojima et al. fails to provide for a pressing process to form optical fibers receiving grooving or features on a substrate in a precise manner. 
   Choquette, et al. U.S. Pat. No. 5,861,113 discloses the fabrication of embossed diffractive optics with a reusable release agent, such as a fluorinated silane and then applying coatings of an epoxy resin. The method described in this publication produces a plastic diffractive pattern through the pressing of a curable plastic against a master. The publication is only adapted to provide for diffractive optics and does not disclose any applicability to a wide range of optical devices where the replication method pursuant to the invention has found broad potential utilizations. 
   Foley et al. U.S. Pat. No. 5,500,914 discloses an optical interconnect unit and method of manufacture thereof adapted to produce an optical connector through molding. The replication method pursuant to the invention and the arrangement employs pressing procedure forming a so-called mold of a sub-master is not at all disclosed nor suggested in the patent, and consequently the present invention pertains to a broad concept of producing optical devices unlike that of the Foley et al. patent. 
   Boyd et al. U.S. Pat. No. 5,343,544 discloses the manufacture of optical couplers which contains aligned wave channels. Although some similarities with the inventive concept may be ascertained from this publication, the latter is limited to optical couplers and cannot be employed to the production of diverse types of devices. Moreover, the publication utilizes the use of a master wherein the mold loses precision due to material differences, thermal variations and surface flaws which may be evident in the substrates. To the contrary, unlike this patent, the inventive master is utilized in the manufacture of a final component, whereas the publication employs the master so as to produce a mold which can lose the strict tolerances during subsequent replication due to mold wear. Moreover, the invention employs a pressing process providing for precision scribing of the features into the surface of the substrate so as to enable accurate positioning of optical fibers or coupling components, whereas the publication employs less precise photolithography and silicon etching methods. Thus, the publication is limited to an aspect in affording a limited method of manufacture for fiber optic couplers and waveguide channels, unlike the present invention which enables the replication process to be employed for the most diverse types of optical devices. 
   Kakii et al. U.S. Pat. No. 5,416,868 describes optical connectors in which a resin molding portion is employed, including opposite open portions at top and bottom surfaces adapted to receive connector pins and optical components. The resin molding process is not adapted to provide the unique method of replication and arrangement as described herein wherein a wide array of diverse types of optical devices can be produced through a unique submaster. 
   Finally Shaw et al. U.S. Pat. No. 4,536,058 is directed to a method of manufacturing a fiber optic directional coupler of a completely different structure and aspect, and produces various optical fibers for tying various devices together. This has nothing in common with the novel replication method and arrangement for producing optical devices in a precise manner analogous to that disclosed by the present invention. 
   SUMMARY OF THE INVENTION 
   Accordingly, in order to obviate or ameliorate the limitations encountered in the prior art, particularly pertaining to concepts pertaining to arrangements and methods for replicating features on optical devices, the present invention is directed to the provision of an apparatus and a process which involves copying a pattern of intricate features, such as grooves, embosses or the like from a precision master through the precise position of a master employed in a pressing step. Resultingly, the respectively employed optical base structure and the optical components have patterns of the features formed on mating surfaces, with the assemblies adapted to be passively aligned upon being assembled. 
   Basically, the present invention provides for an improved and unique arrangement and replication method for optical devices, wherein the master part is constructed in that a submaster is produced which acts as a so called “mold” for the replication of couplers or other optical devices of the most diverse types, such as waveguides, filters, mirrors, beam splitters, prisms, lenses and the like. In connection with the foregoing, a suitable epoxy layer and a parting agent may be mounted on or imparted to the top surface of the submaster, wherein the epoxy layer of the coupler is formed against the parting agent on top of the groove surface of the submaster, thereby producing the pattern which is required to locate the optical fibers. Although epoxy is referred to herein, the master material may include any thermally ultrastable material, which may be referred to as “ULE” (ultralow expansion) material for the master or the part. This is basically a non-crystalline glass material produced by Coming Corporation which enables forming a broader field of groove dimensions and shapes, unlike the current technology wherein the grooves are limited to a V-shape of generally 54.7° which silicon crystals possess subsequent to etching. Inasmuch as an amorphous material may be employed by the present invention, it is possible to provide a considerable variety of cross-sectional groove shapes allowing for a broader range of applications rather than merely typical couplers, inasmuch as the grooves can possess curved, sides, non-symmetrical cross-sections, vertical faces and so forth, in contrast with the state-of-the-technology. 
   Rather than employing photolithography and/or chemical etching to provide the features on the surface on the master which is employed for replication, the various kinds of features can be inscribed and replicated due to the use of non-crystalline materials whereby smooth bends and/or curves can be imparted thereto. This is particularly directly beneficial to waveguide applications for circuit boards and card designs. 
   Accordingly, it is an object of the present invention to provide a novel arrangement and method for the accurate replication of features on optical devices. 
   Another object of the present invention resides in the provision of an arrangement and method for the replication of features, such as grooves and the like, in the surfaces of diverse optical devices so as to be able to accurately position optical fibers therein. 
   Still another object of the present invention resides in the provision of an arrangement and method for the replication of features in an accurate manner in the surfaces of a wide range of optical devices, such as couplers, waveguides, beam splitters, mirrors, lenses, filters, prisms, and the like. 
   Still another object of the present invention resides in the provision of an arrangement and method which produces the desired features in effecting an accurate replication on the surfaces of optical devices through the imposition of pressure employing a master as a so-called mold structure. 

   
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     Reference may now be made to the following detailed description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings; in which: 
       FIG. 1  illustrates, generally diagrammatically, a perspective view of an optical device formed by the replicating method pursuant to the invention; 
       FIG. 2  illustrates, on an enlarged scale, general diagrammatically an end view of the optical device of  FIG. 1 ; 
       FIG. 3  illustrates on an enlarged scale, a fragmentary portion of the substrate showing the optical features formed therein, in the encircled area A in  FIG. 1 ; 
       FIG. 4  illustrates a perspective view of an optical device employing the structure pursuant to the invention; 
       FIG. 5  illustrates, diagrammatically, a view of a coupler illustrating the features produced pursuant to  FIG. 4  of the invention; 
       FIG. 6  illustrates an arrangement for an optical coupler replication implemented pursuant to the present invention; 
       FIG. 7  illustrates on a smaller scale generally diagrammatically, an exploded view of the structure of  FIG. 6 ; and 
       FIG. 8  illustrates, on an enlarged scale, a perspective fragmentary view of the encircled portion B in  FIG. 1 , showing an alternative configuration of the features produced by the replication method pursuant to the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now specifically to  FIG. 1 , there is illustrated an optical coupler device  10 , comprising a substrate  12  which includes a surface  14  having grooves  16  formed therein, as shown in the enlarged detail of  FIG. 3 , for the receipt of optical fibers  18  and pin connections  20 , the precise structure of which is known in the technology. In essence, as shown in  FIGS. 1 and 2  of the drawings; mounted on the substrate  12  are optical devices  22 , including active operating devices  24  and beam splitters  26  forming so-called “smart islands”. As shown in particular in  FIG. 2  of the drawings, received in the grooves  16  which are formed in the upper surface  14  of the substrate  12 , the latter of which may be constituted of a ceramic or plastic material or an ultalow expansion non-crystalline glass material (i.e. such as ULE), are the optical fibers  18  which communicate with the active operating devices  84 , and the optical devices  22  and chip locations  28 . 
   As illustrated specifically in  FIG. 4  of the drawings, the optical device may be a silicon coupler  30 , wherein as shown in  FIG. 5 , a lower substrate  32  thereof comprises a coupler having grooves  16  or suitable features molded therein for receiving optical fibers  18 , and also pins  20  for forming the necessary electrical or transmissive connections. An upper suitable portion  34  may then be fastened by means of an adhesive  36  to the coupler substrate  32 , as shown in  FIG. 5  of the drawings. 
   In order to be able to replicate the optical devices  24 , and in essence, the coupler substrate  32  and the features therein, as shown in  FIG. 6  of the drawings a submaster substrate  40  may be provided, and which already has a submaster epoxy layer  41  with grooves  42  formed therein. The epoxy layer  41  is applied in a liquid state, and is then hardened or cured at either room temperature or alternatively by heating to accelerate the curing. The submaster substrate  40  may be constituted of either a suitable thermally ultrastable material, such as a ultralow expansion material (ULE) as produced for example by Corning Corporation. This material is a glass material of a non-crystal like nature which permits the formation or molding therein of a broad spectrum of groove dimensions and shapes. The cured epoxy grooves  42  may have curved sides, non-symmetrical cross-sections, vertical faces and so forth which facilitate their applications to the producing of various types of optical devices, which are not only limited to optical couplers, as is well known in the prior art, but rather expanded also to waveguides, filters, lenses, mirrors, prisms, beam splitters and similar optical devices of diverse kinds established in the technology. 
   The submaster substrate  40  has the desired features  42  such as grooves and the like provided therein through the intermediary of precision scribing in a positive manner, unlike the prior art which ordinarily employs either photolithographic and/or chemical etching processes. As shown in  FIGS. 6 and 7 , a metal coating  46  may be applied to the epoxy layer  41  on the submaster substrate  40 , such coating being possibly constituted of any suitable metals; for instance, preferably such as but not limited to aluminum, copper, or the like, and thereafter applied thereon is a parting agent  48 , which may comprise a silane or resin material. This parting agent has no optical effects and is merely provided to aid in the separation between components  32  and  40 . 
   The coupler substrate  32  or the substrate for the optical device which is to be produced, has a layer of a moldable material  50  provided thereon, such as an epoxy or the like, then through implementing a compressive action between the coupler  30  or optical device substrate  32  or the submaster substrate  40 , as shown in  FIG. 6 , the epoxy material  50  is imparted the desired feature configuration, in effect the grooving or other shapes, i.e. curvatures, which may be desired for enabling the positioning therein of the optical fibers  18  or the like. 
   Thereafter, the coupler  30  or optical device substrate  32  is separated from the submaster substrate  40 , with the parting agent  48 , such as the silane enabling separation between the parts while permitting the moldable material  50 , in effect the epoxy or the like to remain on the planar surface of the substrate  32  which forms the optical coupler  30  or the optical device. 
   Thereafter, the submaster substrate  40  may have a further layer of parting agent  48  applied thereto, and another coupler  30  or optical device substrate  32  having a epoxy layer  50  thereon or other suitable moldable material positioned and pressed and cured thereagainst so as to replicate the preceding method and to resultingly form additional optical device substrates having the precisely conformed features provided therein in a rapid and economical manner. 
   The foregoing inventive method and arrangement avoids costly photolithographic or chemical etching processes, and also reduces the potential wear and cost of the components. In the event that during continued and repeated use the submaster substrate  40  is worn down; in effect there is encountered a deterioration due to wear of the features and any damage, it is an inexpensive and simple matter to replace this structure with a further submaster substrate  40  having the metal layer or coating  46  provided thereon. This avoids the need to provide further submasters necessitated by means of photolithographic processes or chemical etching. 
   Moreover, in accordance with the present invention, inasmuch as the features, such as grooves  16 , are inscribed rather than formed through photolithographic and/or chemical etching, it becomes a simple expedient to impart different configurations to the feature, such as cross-wise grooves  60  and ridges  62 , or embossings, as shown in  FIG. 8  of the drawings. Furthermore, it is also possible to produce (not shown) curvilinear shapes or grooves having differently sloped angles and flank or side surfaces, such as a vertical side and an angled side, flat bottomed grooves, and/or any combinations thereof. 
   From the foregoing, it becomes readily apparent that the invention provides further improvements upon the replication apparatus and method provided for in the prior art, particularly with regard to that shown in the Boyd et al. U.S. Pat. No. 5,343,544, regarding which the present invention considerably improves and increases the versatility in the production of optical devices, which on the basis of the inventive arrangement and method are not limited to optical couplers but are expanded to extend over an entire spectrum of the optical technology. 
   While the invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.