A high efficiency input/output coupler for small silicon photonic devices

Coupling light from an optical fibre to small optical waveguides is particularly problematic in semiconductors, since the refractive index of the silica fibre is very different from that of a semiconductor waveguide. There have been several published methods of achieving such coupling, but none are sufficiently efficient whilst being robust enough for commercial applications. In this paper experimental results of our approach called a Dual-Grating Assisted Directional Coupler, are presented. The principle of coupling by this novel method has been successfully demonstrated, and a coupling efficiency of 55% measured

Silicon photonics: are smaller devices always better?

There is a worldwide trend towards miniaturising silicon photonic waveguides for both performance and cost reasons. It is clear than in many circumstances the shrinking of the device dimensions provides advantages in terms of cost and packing density, modulation bandwidth, improved performance in resonant structures, and an increase in optical power density within the devices. However, the size reduction comes at some costs in increased difficulty in maintaining single mode operation of the waveguides whilst controlling the polarisation properties of the device. Furthermore, the difficulty of coupling into and out of these devices is increased due to the mismatch in size and refractive index with an optical fibre

Multi-stage racetrack resonator filters in silicon-on-insulator

In an effort to find low-cost alternatives for components currently used in dense wavelength division multiplexing (DWDM), various devices fabricated on silicon-on-insulator (SOI) have been investigated. Many include modulators, filters, and switches that can be realized with a ring or racetrack resonator. For such devices to be commercially viable, they need to be insensitive to the polarization state of the input signal. Herein we discuss the design of polarization-independent multi-stage racetrack filters in SOI and compare this design with a single-stage configuration

Fabrication of low-loss silicon-on-oxidized-porous-silicon strip waveguide using focused proton-beam irradiation

We have successfully fabricated low-loss silicon-on-oxidized-porous-silicon (SOPS) strip waveguides with high-index contrast using focused proton-beam irradiation and electrochemical etching. Smooth surface quality with rms roughness of 3.1 nm is achieved for a fluence of 1x1015/cm2 after postoxidation treatment. Optical characterization at a wavelength of 1550 nm shows a loss of 1.1±0.4 dB/cm and 1.2±0.4 dB/cm in TE and TM polarization respectively, which we believe is the lowest reported loss for SOPS waveguides. This opens up new opportunities for all-silicon-based optoelectronics applications

Freestanding waveguides in silicon

10.1063/1.2749175Applied Physics Letters9024-APPL

Waveguides for mid-infrared group IV photonics

10.1109/GROUP4.2010.5643320IEEE International Conference on Group IV Photonics GFP374-37

Novel fabrication techniques for silicon photonics

10.1117/12.705180Proceedings of SPIE - The International Society for Optical Engineering6477-PSIS

Future prospects for silicon photonics

10.1117/12.736867Proceedings of SPIE - The International Society for Optical Engineering6593-PSIS