Serge Bidnyk

Tunable All Optical Switch Implemented in a Liquid Crystal Filled Dual-Core Photonic Crystal Fiber

We propose an all optical switch in a dual-core photonic crystal flber (PCF) that has the core region consisting of soft glass and has nematic liquid crystal fllled holes in the cladding region. Light waves are guided in this PCF by total internal re∞ection (TIR) due to the refractive index contrast between soft glass and liquid crystal (LC). Its wavelength dependent coupling, birefringence and dispersion are calculated and later use these parameters to evaluate the switching characteristics of short pulses propagating through this optical waveguide. The switch demonstrates tunability with external perturbation such as applying external heat source or electric fleld. Refractive index sensitivity of LC with these perturbation as well as polarization of the light signal determines the coupling, birefringence and dispersion properties of the overall waveguide and its switching characteristics.

Cascaded optical microspectrometer based on additive dispersion planar gratings

We demonstrate that planar reflective gratings can be used to design a cascaded microspectrometer that is capable of processing optical signals with different spectroscopic signatures. The filter is based on a double-grating additive dispersion architecture. The first planar grating is used to multiplex single-mode signals from the 1310-nm band into the fiber and weakly demultiplex the band around 1550 nm from the fiber. The second grating doubles the dispersion of the first grating, improves the rejection of stray light, and produces a box-like spectral response around 1550 nm at the output. The device was fabricated using a standard silica-on-silicon process with a refractive index contrast of 0.82% and has a remarkably small footprint of only 0.29 cm/sup 2/. Experimental measurements of the device show Gaussian-shaped spectral response at 1310 nm with a 1-dB bandwidth of 21 nm and box-like transmission at 1550 nm with a bandwidth of 33 nm. The insertion losses for the two channels were measured to be -4.7 and -5.8 dB, respectively. To the best of our knowledge, this is the first demonstration of an integrated planar lightwave circuit that is based on multiple reflective gratings. Applications of the microspectrometer for biophotonics, spectroscopy, and telecommunications are discussed.

Silicon-on-insulator platform for building fiber-to-the-home transceivers

A silicon-on-insulator platform is proposed for building bi-directional transceivers for fiber-to-the-home applications. The platform includes a monolithically integrated planar reflective grating and a multi-stage interferometer combined with hybridization structures for placement of lasers and photodetectors.

Synthesis of Planar Reflective Gratings for Silicon Interconnects

The design and simulations of planar reflective gratings for building optical interconnects in silicon-on-insulator (SOI) were studied for a range of silicon core thicknesses of 0.1 to 10 𝜇m. The verticality of the grating facets has been shown to be the main contributing factor to the cumulative crosstalk in thick silicon cores. The dispersion property of the slab was found to limit the minimal thickness of the core for polarization-insensitive gratings. The effects of polarization-dependent confinement on optical crosstalk were studied. The findings were used to design and simulate a polarization-insensitive 18-channel coarse wavelength division demultiplexer (CWDM) with a free spectral range of over 600 nm. The CWDM demultiplexer uses a 1.7 𝜇m silicon core and combines a shallow-etch tapered rib structure and multimode silicon channels to produce box-like passbands for integrated receiver applications. The diffraction grating was constructed using double astigmatic point design with phase-corrected grating facets to reduce astigmatism. Optical properties of the planar gratings have been simulated using quasivectorial diffraction grating theory. The simulation results confirm that there is high diffraction efficiency and low optical crosstalk over the entire range of operation. Applications of planar silicon gratings to the synthesis of silicon interconnects are discussed.

The evolution and commercialization of large scale photonic circuits

Specific product examples are used to demonstrate the technical challenges and opportunities that have been faced while commercializing advanced planar lightwave circuits.

Narrow and wide free spectral range devices based on planar reflective gratings

A new approach for constructing devices of various free spectral ranges (FSRs) is described. We show that devices with different FSRs can be built around the same aberration-free architecture based on elliptical grating facets. Elliptical facets, combined with double astigmatic point design, are demonstrated to lead to dramatic improvements in reflective grating performance compared to traditional flat facet designs. A discussion on the proper selection of the grating order for devices with various FSRs is given. The proposed theory was applied to manufacture devices with various FSRs. A standard silica-on-silicon process was used to fabricate interleavers with narrow FSR of 0.8 and 1.6 nm. Subsequently, we show how the above methodology can be used to scale the reflective grating design to devices with wide FSR. We applied the theory to produce coarse wavelength division multiplexing filters with FSR in excess of 500 nm. The filters exhibited insertion losses of 2.5 dB and polarization dependent losses of less than 0.2 dB. Applications of wide FSR devices in metro edge and access networks are discussed.

32-channel integrated receiver module for WDM-PON applications

WDM-PON offers distinct advantages over competing technologies, but has typically come at the expense of high component costs and low OLT port densities. We present an integrated PLC-based receiver module that integrates 32 APD receivers along with a demultiplexer and integrated temperature controller, in a compact module with high performance.

90 ◦ SOI optical hybrid for Radio-over-fibre links

Radio-over- fibre (RoF) technology is receiving large attention due to its ability to provide simple antenna front ends, increased capacity and increased wireless access coverage. Coherently detected RoF systems would enable the information to be carried in both the amplitude and phase or in different states of the polarisation of the optical field. Additionally, the selectivity of coherent receiver is very well suited for access networks. We present a 90° optical hybrid built on a silicon-on-insulator planar light-wave circuit, which can be used as the optical front end of the digital coherent receiver in a digitised RoF link and will lead to reduced receiver footprint and cost. The optical hybrid circuit includes 2 × 2 and 4 × 4 multimode interference (MMI) splitters, in a polarisation diversity configuration. The simulation results at vacuum wavelength 1,550 nm show polarisation independence and phase errors between the ports of less than 0.03°. The properties of the prototyped 4 × 4 MMI were measured over a wide range of wavelengths. The 2 × 2 and 4 × 4 MMI showed nearly equal splitting ratios. Measurements of the relative phase relationship between the ports for Transverse Electric mode polarisation are shown to match the simulation results.

Large-scale planar lightwave circuits

By leveraging advanced wafer processing and flip-chip bonding techniques, we have succeeded in hybrid integrating a myriad of active optical components, including photodetectors and laser diodes, with our planar lightwave circuit (PLC) platform. We have combined hybrid integration of active components with monolithic integration of other critical functions, such as diffraction gratings, on-chip mirrors, mode-converters, and thermo-optic elements. Further process development has led to the integration of polarization controlling functionality. Most recently, all these technological advancements have been combined to create large-scale planar lightwave circuits that comprise hundreds of optical elements integrated on chips less than a square inch in size.

Hybrid Transmitter Cells for DWDM Systems

A compact 10 Gb/s transmitter cell for 100 Gb/s DWDM transmission has been successfully developed using hybrid PLC technology. It is confirmed that the hybrid transmitter cell provides high performance on output power and wavelength stabilization.