Multimode polymer waveguide components for complex on-board optical topologies

Multimode polymer waveguides are an attractive transmission medium for board-level optical links as they provide high bandwidth, relaxed alignment tolerances, and can be directly integrated onto conventional printed circuit boards. However, the performance of multimode waveguide components depends on the launch conditions at the component input, complicating their use in topologies that require the concatenation of multiple multimode components. This paper presents key polymer components for a multichannel optical bus and reports their performance under different launch conditions, enabling useful rules that can be used to design complex interconnection topologies to be derived. The components studied are multimode signal splitters and combiners, 90°-crossings, S-bends, and 90°-bends. By varying the width of the splitter arms, a splitting ratio between 1% and 95% is achieved from the 1 × 2 splitters, while low-loss signal combining is demonstrated with the waveguide combiners. It is shown that a 3 dB improvement in the combiner excess loss can be achieved by increasing the bus width by 50 μm. The worst-case insertion loss of 50 × 100 μm waveguide crossings is measured to be 0.1 dB/crossing. An empirical method is proposed and used to estimate the insertion losses of on-board optical paths of a polymeric four-channel optical bus module. Good agreement is achieved between the predicted and measured values. Although the components and empirical method have been tailored for use in a multichannel optical bus architecture, they can be used for any on-board optical interconnection topology. © 1983-2012 IEEE.

PCB-integrated optical waveguide sensors: An ammonia gas sensor

This paper presents a novel platform for the formation of cost-effective PCB-integrated optical waveguide sensors. The sensor design relies on the use of multimode polymer waveguides that can be formed directly on standard PCBs and commercially-available chemical dyes, enabling the integration of all essential sensor components (electronic, photonic, chemical) on low-cost substrates. Moreover, it enables the detection of multiple analytes from a single device by employing waveguide arrays functionalised with different chemical dyes. The devices can be manufactured with conventional methods of the PCB industry, such as solder-reflow processes and pick-and-place assembly techniques. As a proof of principle, a PCB-integrated ammonia gas sensor is fabricated on a FR4 substrate. The sensor operation relies on the change of the optical transmission characteristics of chemically functionalised optical waveguides in the presence of ammonia molecules. The fabrication and assembly of the sensor unit, as well as fundamental simulation and characterisation studies, are presented. The device achieves a sensitivity of approximately 30 ppm and a linear response up to 600 ppm at room temperature. Finally, the potential to detect multiple analytes from a single device is demonstrated using principal-component analysis. © 1983-2012 IEEE.

Polymer waveguide-based backplanes for board-level optical interconnects

Optical interconnects are increasingly considered for use in high-performance electronic systems. Multimode polymer waveguides are a promising technology for the formation of optical backplane as they enable cost-effective integration of optical links onto standard printed circuit boards. In this paper, two different types of polymer waveguide-based optical backplanes are presented. The first one implements a passive shuffle architecture enabling non-blocking on-board optical interconnection between different cards/modules, while the second one deploys a regenerative bus architecture allowing the interconnection of an arbitrary number of electrical cards over a common optical bus. The polymer materials and the multimode waveguide components used to form the optical backplanes are presented, while details of the interconnection architectures and design of the backplanes are described. Proof-of-principle demonstrators fabricated onto low-cost FR4 substrates, including a 10-card 1 Tb/s-capacity passive shuffle router and 4-channel 3-card polymeric bus modules, are reported and their optical performance characteristics are presented. Low-loss, low-crosstalk on-board interconnection is achieved and error-free (BER10 12) 10 Gb/s communication between different card/module interfaces is demonstrated in both polymeric backplane systems. © 2012 IEEE.

Compact multimode polymer waveguide bends for board-level optical interconnects

Multimode polymer waveguides are promising for use in board-level optical interconnects. In recent years, various on-board optical interconnection architectures have been demonstrated making use of passive routing waveguide components. In particular, 90° bends have played important roles in complex waveguide layouts enabling interconnection between non co-linear points on a board. Due to the dimensions and index step of the waveguides typically used in on-board optical interconnects, low-loss bends are typically limited to a radius of ∼ 10 mm. This paper therefore presents the design and fabrication of compact low-loss waveguide bends with reduced radii of curvature, offering significant reductions in the required areas for on-board optical circuits. The proposed design relies on the exposure of the bend section to the air, achieving tighter light confinement along the bend and reduced bending losses. Simulation studies carried out with ray tracing tools and experimental results from polymer samples fabricated on FR4 are presented. Low bending losses are achieved from the air-exposed bends up to 4 mm of radius of curvature, while an improvement of 14 μm in the 1 dB alignment tolerances at the input of these devices (fibre to waveguide coupling) is also obtained. Finally, the air-exposed bends are employed in an optical bus structure, offering reductions in insertion loss of up to 3.8 dB. © 2013 IEEE.

Low-cost PCB-integrated polymer waveguide sensor for gas detection

An optical waveguide sensor formed directly on low-cost PCB substrates is presented for the first time. The device integrates polymer waveguides functionalized with chemical dyes, photonic and electronic components and allows multiple-gas detection. © 2011 OSA.

Low-cost PCB-integrated polymer waveguide sensor for gas detection

An optical waveguide sensor formed directly on low-cost PCB substrates is presented for the first time. The device integrates polymer waveguides functionalized with chemical dyes, photonic and electronic components and allows multiple-gas detection. © OSA/CLEO 2011.

Mode-locking using right-angle waveguide, based nanotube saturable absorber

We report passive mode-locking of an Er-doped fiber laser using carbon nanotubes deposited on the facet of a right-angle optical waveguide. © 2013 IEEE.

A polymer waveguide-based 40 Gb/s optical bus backplane for board-level optical interconnects

Optical interconnects are increasingly considered for use in high-performance electronic systems. Multimode polymer waveguides are a promising technology for the formation of optical backplanes as they enable cost-effective integration of optical links onto standard printed circuit boards. In this paper, we present a 40 Gb/s optical backplane demonstrator based on the use of polymer multimode waveguides and a regenerative shared bus architecture. The system allows bus extension by cascading multiple polymeric bus modules through 3R regenerator units enabling the connection of an arbitrary number of electrical cards onto the bus. The proof-ofprinciple demonstrator reported here is formed with low-cost, commercially-available active devices and electronic components mounted on conventional FR4 substrates and achieves error-free 4×10 Gb/s optical interconnection between any two card interfaces on the bus. © 2013 IEEE.