Optical InterLinks (OIL) is recognized as the leader in practical polymer waveguide technology and is the first and only commercial supplier of custom polymeric optical links and functional circuits. OIL supplies uniquely configured polymeric waveguide and fiber based optical interconnections. Referred to as GuideLink™ products, OIL's polymeric functional and optical link components and interconnects are fully connectorized and robustly packaged. GuideLink™ products include polymeric planar waveguide connections typically mounted on boards; compact signal distribution splitters, combiners and star coupler components; and optical sensor devices.
Complementary to the polymer products, OIL's fiber based DistributionLink™ products are fully connectorized custom fiber ribbons and wiring harness shuffles with protective ribbon cabling. Ribbons with up to 64 fibers of any size and length can be made and connectorized. DistributionLink™ products provide considerable design freedom for the customer, removing the constraint of using only 8 or 12 standard size fibers per ribbon. Both GuideLink™ and DistributionLink™ products use proprietary technology and are connectorized and interconnectable with standard or custom connectors. Self-supporting robust packaged and substrate attached components are optimized to meet customers' unique requirements and applications.
Preliminary GuideLink™ and DistributionLink™ Product Briefs written to date are attached and highlighted below. (Click title to connect to pdf.)
TxRx Optical Links for Flip Chip Components
Custom designed multimode polymer waveguide TxRx arrays have been created in self supporting multilayer films. Laser micromachining singulates array strips from larger film sheets, creates I/O mirrors and coupling interfaces. Waveguides are separately optimized by design for Tx and Rx functionality. After completing QC, waveguide strips with attached board edge connectors forming a self supporting component link are precisely aligned and bonded on a range of typical substrates such as FR 4, ceramic, glass, semiconductors... VCSEL’s and PD’s are aligned and flip chip bonded over the I/O mirrors using standard IR solder reflow processing.
Additional Photo Details
In the adjoining interposer board photo OIL waveguide films provide a Tx and Rx array link mounted on FR4 substrates with standard MT style connector ferrules at the board edge. Extremely small footprint thin “micro” connector ferrules compatible with MT style interfaces have been developed for alternative compact packaging. The I/O deflecting mirrors are silver coated performing with ≤0.3 dB excess loss. In this example twelve waveguides within each link are spaced on standard 250 micron centers with pitch run-outs of less than +/- 3 microns. Waveguides are typically positioned within less than +/- 4 microns offset from the ideal position in both the X and Y directions relative to the solder balls that align, connect and bond the flip chip VCSELs and PD components. Waveguide film arrays shown here are ~ 95 microns thick with the waveguide buried in the film center being nominally ~40 microns by 40 microns. Both guide size and film thickness can be varied over a broad range. Waveguides are often optimized for Tx and/or Rx operation relative to coupling to/from optical fiber cores. The waveguide loss in the 840 nm range is ≤ 0.1 dB/cm and at 980nm is ≤ 0.3dB/cm. The substrate bonded waveguide films can be subjected to the required 230 C IR thermal spike profile for 30 seconds to melt and bond the solder balls between board and flip chip components. Link operating temperature range meets typical requirements for –45C to 85C or higher if need be.
TxRx Optical Links for Underlying Components
Multimode polymer waveguide arrays are configured as self supporting TxRx links between underlying components and fiber arrays. Component interfaces are achieved by I/O mirrors with optional lens arrays for larger offset distances. Link output to fiber arrays or other waveguides is through custom or standard ferrules. Processing and designs for these self supporting links are identical to substrate bound links for flip chip interconnections. Alignment structures are created with micromachining for ease of precision assembly and location of waveguides, lenses, VCSEL’s and PD’s.
Additional Photo Details
The adjoining photo shows an OIL waveguide-containing film in a Stratos (Div. of Emerson) Tx Rx package mounted as a self supporting flex link. This flex optical link example connects between 4 VCSELs and 4 PDs through a lens waveguide I/O mirror array to a micro “MT style” ferrule on a fiber ribbon array. The interconnection from the fiber array ferrule to the polymer waveguide array is achieved using a micro ferrule structure that is precisely aligned with and attached to the waveguide array. The entire fiber ribbon ferrule connection is located inside the package, with the fiber ribbon array exiting through the sealed package wall. The waveguide array has a silver coated I/O deflecting mirror at the film edge that is precisely aligned over a lens array that images the waveguides to the VCSELs and PD’s that are located on the under side of a transparent substrate. Several precision alignment plates designed, machined and installed by OIL are used throughout to facilitate rapid assembly and maintain precise low loss interconnections. The eight 250 micron spaced waveguides have typical pitch run-outs of less than +/- 3 microns. The waveguides are individually positioned within less than +/- 3 microns offset from the ideal position in both the X and Y directions facilitated by precision alignment structures. Waveguide film array thickness for this application is ~ 180 microns with the waveguides positioned in the film center. Waveguides are nominally ~40 microns in height and 50 microns wide for the receiver circuit to maximize coupling from the fiber. Likewise the transmitter waveguides are 30 microns wide to maximize coupling into the center of the graded index 62.5 micron fiber core. Both waveguide width and thickness can be varied over a broad range depending on the application requirements and can be optimized as noted for Tx and/or Rx operation relative to coupling to/from optical fiber cores, VCSELs and PD’s. The waveguide loss in the 840 nm range is ≤ 0.1 dB/cm resulting in the entire system loss for the link shown here being in the 1 to 1.5 dB range. The self supporting waveguide films have been subjected to 125 C for over an hour with no mechanical issues or distortion or adverse performance impact.
Optical Multimode Splitters
Custom multimode polymer waveguide splitters are available with desired odd or even number of outputs and various custom connectorization options. These options include, but are not limited to, packaging with MT style output ferrules and single ferrule input, or fiber pigtails for all I/O. Outputs greater than 12 can be stacked with up to 4 rows of 12 using OIL’s unique folded splitter designs and standard commercially available MT ferrules. Other connectors can be evaluated to meet customer application requirements.
Additional Photo Details
The adjoining photo shows a standard configuration for a connectorized OIL 1 to 16 multimode splitter. . Standard MT style connectors with MTP latchable housings permit only 12 waveguides or fiber cores with 250 micron spacing between the alignment pins, thus OIL’s 16 outputs are divided up into an 8 over 8 configuration. OIL technology uniquely enables the film to be precisely cut and folded over each other creating the overlapping or folded 8 over 8 or other higher port configurations. Unique output configurations can be created by slicing/folding the self supporting waveguide films as required for custom connectorization options. Single inputs using FC, ST, LC connector ferrules etc are available upon request. For reasonable mode filled inputs OIL’s splitter outputs are well balance within +/- 0.5 dB To achieve well balanced outputs over a range from very low to high mode filled inputs, OIL has developed input mode scramblers imaged inside the waveguides, enabling input modal independent devices to be configured. Typical losses for the 1x16 splitter shown are around 1.8 dB excess at 838nm. OIL’s light induced diffusion based self development waveguide formation process creates extremely sharply defined split junctions (no polymer removal and backfill is required) that produce minimal scatter excess loss at the split junctions along with extremely smooth waveguide side walls (no etching or mechanical tool contact to define the guides). Splitters from 1 to 2 consecutively to the 30 ouputs can be designed for custom applications.
Multimode Waveguide Combiners
Combiners with up to 8 customer defined inputs are configured with multimode polymer waveguides using butt or I/O mirror coupled diode laser inputs. Efficient designs are optimized for desired output into optical fibers accounting for fiber core size, NA and input number. Waveguide film strips can be self supporting or substrate attached and packaged with pigtail or connector ferrule output.
Additional Photo Details
The adjoining photo shows an OIL 8 to 1 multimode combiner mounted inside a package with 8 diode lasers and a single fiber coupled output passing thru the package wall. Specially designed waveguides collect the 8 separate input wavelengths and combine it with minimal optical loss thru stages into a single output capable of low loss coupling into a graded index 62.5 micron core fiber. Using unique design techniques configurations for combining up to 16 possibly higher inputs can be configured. The critical design issue is to keep the combining losses to a minimum compatible with waveguide output dimensions for low loss fiber coupling. OIL has developed design techniques to achieve this low loss combiner capability including the ability to affect combining in both the vertical and horizontal directions for high port count combiners. The 8 to 1 combiner example operated at 838nm demonstrated a fundamental excess loss of 1.6 dB in the combining mode and 1.5 dB in the splitting mode when operated in reverse. Additional combining losses occur due to the polymer guide step index profile coupling into the usual 62.5 micron core graded index fiber NA profile which requires the smallest practical polymer guide dimension for good guide to fiber coupling. Practically this produces about 3 dB excess loss for the combiner system example. Coupling into 50 micron GI core fiber creates additional loss since the fiber core dimension with reasonable acceptance NA is even smaller. This requiring additional guide design changes to keep the overall system loss to a minimum.
Star Couplers for Signal Mixing & Distribution
Multiple waveguide inputs are combined and mixed for uniform and balanced distribution into multiple outputs. Fiber pigtail or other custom I/O connectivity as well as packaging or substrate options are available. The precisely defined waveguide splitting / combining junctions inherent with OIL technology enables creation of very efficient devices.
Additional Photo Details
The example device photo is a compact 8 to 8 multimode star coupler with extremely well balanced outputs within +/- 0.5 dB for the eight outputs for each input channel and when comparing all outputs for all eight input channels. Excess loss is 1.3 dB over the fundamental 9 dB for the 8 splits operated at 838nm. OIL waveguide formation technology enables extremely sharply defined split junctions and no side wall scatter for extremely efficient low excess loss devices that is extremely important for low loss star coupler devices. A broad range of star couplers with n inputs to m outputs can be configured on a custom basis to meet diverse requirements. The photo shows an unpackaged MT ferrule to MT ferrule device which can be packaged with MTP or equivalent latchable housings or can be mounted on substrates etc.
Bendable High Density Optical Link Arrays
Self supporting waveguide array links demonstrated no increase in optical loss with 180° hairpin repeatable bending around a 3 mm radius of curvature. To date we have sustained with no adverse impact on performance over 4000 bend repetitions thus far. High density waveguide array links with five micron separation between guides on ~ 40 micron centers as well as bending ROC to 1mm are possible. Links can be fully connectorizable with unique designs to meet application requirements. Bendable high density optical link arrays are under consideration for a diverse range of applications such as through the hinge high speed data optical interconnections replacing micro coax for cell phones and lap tops.
Additional Photo Details
A representative example of the flexibility inherent with OIL’s self supporting polymer waveguide technology is shown in the photo. Waveguide films with hundreds of close pitch dense waveguide arrays, waveguide functional devices (splitters, combiners etc.) can be bent or twisted over an extremely high number of repetitions. To date we have exceeded 4000 bend repetitions with 180 degree hairpin bends as noted above with no loss of optical or mechanical properties. The fundamental bend ROC loss for either imaged guides within the film or film bending is determined by the ROC, the guide dimension in the plane of the bend, and the waveguide refractive index relative to the surround. For OIL's standard multimode waveguides with current guide index of ~ 0.033 over the surround the minimal ROC for no excess bend loss in or out of plane for ~40 micron guides in the bend plane is ~ 3 mm. The ROC minimum scales with dimension such that 15 micron wide guides have a ~ 1mm min ROC. Unique applications employing thru-the-hinge optical links in flip cover cell phones or lap top computers are being pursued.
Optical Link Circuits with Routing Crossovers
Extremely low loss crossovers can provide custom optical waveguide re-routing circuitry for multiple waveguide optical links.. Enabled are rerouting or reordering for parallel waveguide arrays and opportunities for unconstrained signal distribution designs for optical interconnectivity. Light is guided through the cross regions eliminating radiative unguided loss typical in the cross over area. Ten perpendicular mode filled crossings demonstrated less than ~0.2 dB total excess loss.
Additional Photo Details
The photo demonstrates OIL’s unique process capability that enables small regions within multimode waveguides to be left unexposed and thus function as internal deflectors with a lower refractive index than the guide itself. For two crossing waveguides a square or rectangular frame in this case of ~ 4 microns width of lower index thru the ~40 thick waveguide provides for guiding within the crossing region minimizing unguided optical loss. The photo shows two visible wavelengths 633 nm and 520 nm guided thru each other with no obvious scatter loss. Multiple waveguides are also being crossed with the same low loss performance. These internal unexposed structures are being developed and optimized for a number of crossing/rerouting , sensor, and modal control operations.
Custom Optical Fiber Ribbons & Shuffles
Ribbonized optical fibers are available with up to 64 fibers per ribbon, fiber/clad OD from 80 to 500 microns or greater, and lengths from meters to kilometers. Single and multimode hybrid ribbons with custom arrangements can be ordered. Standard and custom modified ferrule connections can be provided. Fiber arrangement manipulation to form shuffles in ribbon format can be provided.
Additional Photo Details
The photo shows 8 fiber hybrid single and multimode fiber ribbons that are tightly wound into precision length ribbon coils. OIL has developed unique algorithms for designing multi-stage resin dies for encapsulating fibers for creating fiber ribbons with a range of fiber thickness to date from 80 to 500 microns OD and 2 to 64 fibers within one ribbon. Our fiber handling capability enables custom distribution arrangements and shuffles to be configured. Ribbons can also be cablized (encapsulation with flex helical wraps around the ribbons). Connectorization with standard MT ferrule / MTP latchable housings or with custom “MT style” ferrules can be provided, the latter to handle unusual number of fibers within a standard ferrule footprint. OIL serves a niche market for unusual fiber ribbon configurations with lengths, numbers, fiber OD dimensions, and single/multimode mix not typically available from other vendors.
Optical Waveguide Sensor or Wavelength Selective Devices
Unique polymer waveguide configurations based on novel OIL designs enable diverse optical devices to be constructed. Light is guided to and from the sensing or filter surface with no or minimal crosstalk or back scatter into the input waveguide. Designs for capillaries, scanners, or wavelength selectivity with inserted dielectric filters are possible and have been demonstrated.
Additional Photo Details
The photo is representative of OIL’s capability to image unexposed regions within waveguides to form optical sensors or wavelength selectivity. Light is directed at and guided to a surface or capillary reflecting or scattering off the to-be-measured system or dielectric filter. It is then guided away from the surface in a returning guide with essentially no unguided radiated or back scatter light returning in the input guide. OIL’s ability to create extremely dense arrays of waveguides and sharply defined splitting configurations for novel bio diagnostic or reaction monitoring systems is also being exploited for sensors. Multimode waveguides with spacing of 5 to 10 microns and guides of 10 to 100 microns in width and 10 to 60 microns in thickness for diverse sensing are being explored and have been demonstrated. As long as the guides operate with reasonable mode fill ---having most of the allowed propagating angles with light ---there is no crosstalk even over long lengths. This is due to coherent destructive interference of the various out of phase evanescent tails for each mode outside the guides. As an example two 10 cm length 50 micron square guides with 10 micron spacing produced no cross talk at least to the system measurement limits of -30 dB or 3 orders of magnitude.
Additional GuideLink™ product briefs to be prepared
Compact sensor read heads ------ Novel configurations of small multi-waveguide read heads are available with desired custom variations and connectorization as required.
Fluidic biochip capillaries ------ Custom configured multi layer films with embedded capillaries and reservoirs are available. Also capillaries in combination with waveguides for sensing or with novel sensing head configurations are possible.
Multimode add-drop multiplexers ------ Dielectric filters are embedded into slots precision machined into waveguide intersections for multimode WDM devices. Connectorization and packaging as required are constructed.
DistributionLink™ product briefs to be prepared
Custom connectorized optical fiber ribbons ------ Ribbons can be created using OIL designed dies using any size fiber, any length, up to 64 fiber per ribbon (expandable to 256) fully connectorized with standard MT footprint or custom configurations as appropriate. Custom cabling for protection around the ribbons can be provided.
Optical InterLinks (OIL) produces custom optical interconnections covering a broad range of application requirements for fully interconnected optical solutions from rack to rack, to backplane, to boards and down to the chip level. OIL has developed product prototyping capabilities for custom optical fiber ribbons and photo imaged self-developing polymer waveguides all fully connectorizable that are based on unique and proprietary technologies. These include:
Custom multiple optical fiber ribbon distribution products. These encompass:
1. custom fiber ribbons using any length or fiber type with up to 64 fibers today (expandable to 256);
2. custom optical fiber distribution for wiring harnesses and for shuffles, either perfect or custom arranged, are created using a proprietary continuous fiber weaving process;
3. fiber ribbon configurations with any length as needed, with no fusion splices, fire retardant ribbon jacketing, small pencil sized form factor for mixing redistribution regions in the ribbon providing nearly equal path lengths for low skew;
4. connectorization with MT style footprint or larger custom based connector ferrules as needed. Proprietary designs enable high density connectors of up to 60 standard 125 micron glass fibers within a standard MT footprint with center to center 2D array format on 250 micron centers and similarly configured but fewer for larger fibers.
Our optical fiber based custom product family is classified under OIL's DistributionLink™ products, which we believe are highly competitive with conventional flex circuit products where fibers are embedded in large polymer sheets. As an example we are currently delivering multiple units of nearly 100 foot lengths each fully connectorized using a) 18 fiber ribbon with standard 62.5/125 micron core/cladding and b) 12 fiber ribbon with 200/250 micron core/cladding for an aerospace application. They will interface to our polymeric splitters and multimode add drop devices noted below.
Examples of Delivered Custom Fiber Based Prototypes
Custom optical fiber ribbons ---Custom optical fiber ribbons with 18 standard fibers and with 12 large core fibers have been made with fire retardant jackets and delivered in large multi-hundred foot lengths fully connectorized with either standard or custom MT style connections for avionic control distribution systems. Current capability permits up to 64 fibers to be handled with design potential to 256.
Optical fiber attenuators ----Extremely high attenuation array links have been created for high peak power attenuations with up to 40 dB loss.
Custom shuffles - Perfect and custom shuffle distribution links / wiring harnesses of up to 16 x 16 have been delivered using our proprietary continuous process design capability.
View of DistributionLink™
OIL's facilities are shown for producing custom optical fiber
ribbons, optical distribution harnesses, perfect and custom shuffles
using proprietary processes. Currently up to 64 fibers of any size
can be handled or manipulated and the equipment is readily expandable
to handle 256. Fire retardant jacket materials are used to encapsulate
the fiber bundles. MT style connectorization in either standard or
custom size and configuration is available as needed using proprietary
designed connectorization at OIL. Shuffles and distribution hubs are
achieved using a continuous ribbon and weaving process producing
compact small footprint packages (pencil size), nearly equal path
lengths (within 1mm or less) for minimal signal skew, and essentially
any length fiber leads/ pigtails with no fusion splices or breaks in
the fibers. These fiber based optical distribution and routing
products are classified under OIL ShuffleLink tm product name.
Polymer waveguides products ------ These are created through photoimaging and self-developing, and the resulting waveguides are symmetrically and precisely placed in large film sheets encapsulated by high Tg low CTE polymers. They are configured using micromachining for routing and linking components and optical fibers with high density and 1 or 2D connectorization for chip to chip, on boards, and board to board interconnections. These products, all classified by OIL under the name GuideLink™, have capabilities that encompass:
1. point to point links and/or) diverse functionality for a broad range of applications and optical functions are possible, such as splitters, crossovers, 5mm ROC and mirrors for in or out of plane, stacked 2D array interconnections with extremely high density, chip or board to board MT style interconnects with standard footprint size compatibility, and multimode guide spacing to less than 10 microns,
2. photoimaged waveguide structures inside guides at crossover junctions produce near zero optical cross-over loss that facilitates a) extremely dense optical circuits at the board level with complex cross over routing, and b) associated multimode sensor heads, sensor devices and add/drop multiplexer filter device applications where filters are coated or inserted into the crossover point,
3. precise connectorization in single or multiple layers in standard MT footprint or custom ferrule designs is enabled by OIL's reproducible film thickness based on our unique guide forming process and precise laser based micromachining combined with our proprietary connector technology, also used for the custom fiber ribbons products above.
4. compatibility with electronic industry manufacturing processes and operational requirements,
5. high volume cost effective near continuous manufacturing processes for complex waveguide circuit/pattern creation using photomasks up to 18 x 12 inches to date.
Products have been and continue to be delivered using or embodying the above attributes or capabilities to numerous customers. Connectorized polymer waveguide board and chip level and custom fiber ribbon array optical interconnection prototype products have been made and delivered for evaluation and for beta test applications to major customers involved in high speed computers and switching applications, high speed transmitter and receiver products, and for aerospace fly by light signal distribution prototyping. Multimode waveguides with embedded dielectric filters using unique photoimaged internal guide structures have been assembled under a prototype development for add drop multiplexers initially for unmanned aircraft systems, but ultimately they could be used for fiber to the home signal distribution.
Examples of Delivered Custom Polymer Based Prototypes
Chip and board level optical interconnection arrays --- Substrate bonded polymeric multimode waveguide arrays with out-of-plane I/O mirrors for VCSEL and PD's and board edge MT style interconnects have been delivered to numerous customer for prototype developmental applications.
Board level interconnections -Polymeric waveguide array interconnects with interconnections to daughter boards and 47 cm runs were delivered for prototype demos.
Component to optical fiber interconnections -- Free standing flex circuits for high data rate multimode interconnections with stacked arrays of 24 and 48 for VCSEL/PD to MT style OF array interconnects have been delivered in large numbers and were in beta testing before market issues postponed deployment.
Flexible jumpers-Freestanding flexible jumpers with MT style interconnections have been delivered for prototype developmental program demonstrations.
Multimode add drop multiplexers ---Using unique waveguide designs with imaged internal structures for low loss crossovers and inserted dielectric filters, multimode add-drop mux devices were delivered for an aerospace signal control distribution demonstration prototype.
Sensor / read heads----Using unique imaged internal structures sensor read heads have been configured for remote optical actuator position sensing.
Splitters / combiners ---Polymer multimode waveguide based 1 to 4 splitters and 4 to 1 combiners have been delivered with low loss and excellent balance for an optical aerospace control system demonstration.
Compact 1x16 splitter designs -Packaged polymeric 1x16 splitters the size of a pencil and about 10 cm long with MT 8/8 stacked outputs and FC input have been constructed and delivered with total loss of 13.5 dB and balance of +/- 0.5 dB.
1x16 Product Information Sheet 
Optical fan out distribution -- Novel single fiber input polymer guide fan-outs to mm spaced output arrays of hundreds of guides were provided for an optical position related application.
Fluidic biochip capillaries --- Using precise machining and film lamination techniques biochip capillaries with reservoirs have been constructed that offer high volume manufacturing potential. Combining the capillaries with the above noted waveguide sensors is under development for optical monitoring of fluidic channels.
A recent market survey by a potential investor indicated that no other group besides OIL had developed and delivered products with practical connectorization for polymer waveguide circuits and devices, and connectorization is considered the critical issue. OIL has been successful due to the unique precoated film self-developing process for creating and embedding waveguides symmetrically in precise thickness films. In-house custom excimer laser equipment and work station for micromachining enables rapid custom work for all proprietary connectorization and part singulation to be under our control. In-house modeling for photomask design specifications, clean room for exposures, lamination of film layers and other optical test, assembly and evaluation equipment are available at OIL.
