Polymeric multimode waveguides are of particular interest for optical interconnections in short-reach data links. In some applications, for example in space-borne systems, the use of advanced materials with outstanding performance in extreme environments is required (temperature and radiation). In this paper therefore, we present novel siloxane polymers suitable for these applications. The materials are used to form straight, 90° bent and spiral polymer waveguides by low-cost conventional photolithographic techniques on FR4 substrates. The samples have been tested to investigate their propagation characteristics and demonstrate their potential for high-speed data links. Overall, there is strong evidence that these multimode waveguides can be successfully employed as high-speed short-reach data links. Their excellent thermal properties, their low cost and the simple fabrication process indicate their suitability for a wide range of space applications.
Pluggable optics are being pushed to their limits in terms of face plate density and power consumption requirements within emerging mega data centers and HPCs applications. Future applications seek silicon photonics based optical engines with ability for high channel count and throughput beyond 1Tb/s. In this paper, we show our results in development of single mode polymer-based optical-electrical PCBs (OEPCBs) supporting the emerging Si-Pho host PCB platforms with multi-terabit on-board routing capability for chip-to-chip communications. Single mode polymer waveguides (SM-PWGs) are fabricated using new photopatternable optical silicone materials (WG-2211/WG-2511-WG2711) on conventional PCBs. Test platform PCB shows designs with varying core sizes (20/15/12/9/7µm) and channel lengths (5-15cm). The measurements results show single-mode waveguides loss as less 0.4 dB/cm at 1310nm. Furthermore, the result show new waveguide material to be compliance for both rigid and flexible PCBs. OEPCB compliance evaluation test results shown in the paper includes results of lamination, chemical compliance, drilling, and plating tests. The results shown in the paper show first time ever fabrication of single mode polymer waveguide OEPCBs in production environment.
We report on the development and optimization of key performance properties of multimode silicone polymer waveguides, manufactured for 850 nm optical propagation. These developments are based on photopatternable, mechanically flexible, low-loss, gradient index waveguides. Cross sectional waveguide core sizes ranging from 40 μm x 50 μm to greater than 60 μm x 60 μm are assessed with optical analysis of component losses such as crossings and coupling between OM4 fiber and waveguide. Assessments of these values, led to optimization of waveguide size and lower total optical system losses. Methods of manufacture, preparation, and analysis are discussed in detail along with performance results.
This paper presents an overview of multimode waveguides and waveguide components formed from siloxane polymer
materials which are suitable for use in optical interconnection applications. The components can be cost-effectively
integrated onto conventional PCBs and offer increased functionality in optical transmission. The multimode waveguides
exhibit low loss (0.04 dB/cm at 850 nm) and low crosstalk (< -30 dB) performance, large alignment tolerances and
negligible mode mixing for short waveguide lengths. Error-free data transmission at 10 Gb/s over 1.4 m long waveguides
has been successfully demonstrated. Waveguide crossings exhibit very low excess losses, below 0.01 dB/crossing, and
excellent crosstalk performance. Low loss is obtained for waveguide bends with radii of curvature larger than 8 mm and
6 mm for 90° and S-shaped bends respectively. High-uniformity splitting is achieved with multimode Y-splitters even in
the presence of input misalignments. Y-combiners are shown to benefit from the multimode nature of the waveguides
allowing low loss combining (4 dB for an 8×1 device). A large range of power splitting ratios between 30% and 75% is
achieved with multimode coupler devices. Examples of system applications benefiting from the use of these components
are briefly presented including a terabit capacity optical backplane, a radio-over-fibre multicasting system and a SCM
passive optical network.
In this work the recent interest in waveguides for use in short optical links has motivated a study of the modal noise
dependence on launch conditions in short-reach step-index multimode polymer waveguides. Short optical links,
especially those with several connection interfaces and utilising a restricted launch are likely to be subject to a modal
noise power penalty. We therefore experimentally study the modal noise impact of restricted launches for a short-reach
optical link employing a 50 x 50 μm polymer multimode waveguide. Lens launches resulting in small diameter input
spots are investigated as are restricted launches from an 8 μm core optical fibre. For a launch spot of 10 μm diameter no
impairment is observed for up to 9 dBo of mode selective loss, and for a fibre launch with a dynamic input movement of
6 μm no impairment is seen for up to 8 dBo of mode selective loss.
The current challenges facing the adoption of optical transmission in printed circuit applications will be discussed and
our recent efforts establishing silicone polymers provide a viable route to manufacturable cost effective hybrid electric-optic
printed circuit boards will be presented.
Silicone based materials have attracted considerable attention from Light Emitting Diode (LED) manufacturers. In LEDs, silicones can function in several roles that include optical lenses, stress relieving encapsulants, mechanical protection and light path materials. The key attributes of silicones that make them attractive materials for high brightness (HB) LEDs include their excellent transparency in the UV-visible region, their non-discoloring behavior and their stable thermo-mechanical properties. The first part of this paper/presentation will describe recent silicone materials development efforts directed towards providing LED manufacturers with silicone materials solutions for LED device fabrication. Injection molding of novel silicone resin based materials will be discussed as a viable route for high throughput LED device manufacturing.
For other portions of the light spectrum, specifically at telecom wavelengths, the performances of silicone based materials are also verified and this makes them attractive materials for numerous photonics device applications. The second part of this paper/presentation will describe recent demonstrations of siloxane for use as waveguides for datacom and telecom applications. A Variable Optical Attenuator (VOA) utilizing silicone based waveguides (exploiting dn/dT property) and an Optical Backplane built from silicone waveguides and out-of-plane mirrors built on glass and FR-4 substrates are discussed.
Siloxanes, which can be viewed as hybrids of glass and organic materials, have been used to fabricate polymer waveguides and devices that exploit the large thermo-optical effect of this material. Siloxanes have many unique properties including good thermal stability, chemical resistance, tunable refractive index, tunable mechanical properties and excellent photo-stability. The refractive index of siloxane polymer is composition dependent and generally ranges from 1.4 to 1.54. Introduction of porosity or composition modification can further expand refractive index range to 1.15~1.63. The loss and absorption characteristics for a variety of silicone-based polymers are examined and an example of a UV curable polymer coating illustrates the flexibility of the silicone polymer family to be tailored to meet specific application needs.
The continuous penetration of optical data transport into diverse applications is driving an imperative to find lower cost fabrication routes to high performance waveguides and devices. Strip-loaded waveguides (SLWG) offer a unique opportunity to enable ultra-low cost processing and excellent performance in these applications. In this paper we will show that simple waveguides and devices may be fabricated that have compelling performance metrics. Similarly it is shown that the waveguide design is easily accomplished and that the designs may be rendered with limiting precision using standard process tool-sets. The combination of good design and facile manufacturing practice suggests that, unlike conventional waveguide technology, the SLWG is eminently suited to a wide variety of applications. It will also be shown that the simplicity of the processing offers new opportunities to apply this approach to waveguides in a wide variety of materials and on diverse substrates.
Forward design and rendition of devices with excellent reconciliation of measured performance with the design parameters provides a feasibility proof for the validity and manufacturability of the SLWG. Perhaps contrary to pre-conception it is proven that very low coupling loss with normal, single mode, fibres is readily achieved with waveguides of this type. This has been shown both by simulation and via the measured performance of devices. Processing of the test artifacts was via conventional silica-on-silicon planar waveguide manufacturing processes. However, other processes are shown to offer a strong proposition for much lower cost and a diversification of the utility and applicability of waveguides on many substrates.
Silicone based polymers possess a unique set of properties that makes them highly suitable for optical applications. In addition to their excellent thermal stability, mechanical properties, and ease of processing, they are highly transparent in the ultraviolet, visible, and selected bands of the near-IR spectra. The loss and absorption characteristics for a variety of silicone based polymers are examined and an example of a recently developed ultra-violet transparent polymer coating that is UV cured illustrates the flexibility of the silicone polymer family to be tailored to meet specific application needs.
Silicone polymeric materials are being developed that will allow the hybrid integration of tunable functionality provided by polymer dispersed liquid crystal, PDLC, and continuous phase liquid crystal materials on planar silica-on-silicon and planar polymer light circuits. The advantages of this approach are ease of integration, the possibility for reduced power consumption, and therefore a reduction of the overall cost for component manufacturing and operation. A successful demonstration of a low loss approach to hybrid integration of polymers and liquid crystals is presented. The challenges for successful integration and acceptance will be discussed. New liquid crystal materials are being developed specifically for this application.
Silicones are known for their excellent performance in applications with harsh environmental conditions. They are very well known for their high temperature stability, resistance to moisture and other adverse conditions. This paper will overview key properties of siloxanes that make them attractive materials for numerous photonics device applications with emphasis on polymer waveguides. Both thermal-mechanical and optical properties will be reviewed. Testing of key optical properties of several siloxane materials, both before and after exposure to heat, humidity, and high optical flux will be discussed. Fabrication and processing for production of polymer waveguides, and the resulting polymer device performance will be shown. Finally, the high reliability of siloxane based waveguides is demonstrated by the Telcordia testing of a fully functional, packaged, Variable Optical Attenuator (VOA).