Widely-tunable, narrow-linewidth III-V/silicon hybrid external-cavity laser for coherent communication.

We demonstrate a III-V/silicon hybrid external cavity laser with a tuning range larger than 60 nm at the C-band on a silicon-on-insulator platform. A III-V semiconductor gain chip is hybridized into the silicon chip by edge-coupling the silicon chip through a SiN spot size converter. The demonstrated packaging method requires only passive alignment and is thus suitable for high-volume production.

Effects of backscattering in high-Q, large-area silicon-on-insulator ring resonators.

We demonstrate large-area silicon-on-insulator ring resonators with Q values of about 2×10 at critical coupling and 3.6×10 for heavily undercoupled conditions. A model has been developed to understand the impact of waveguide backscattering and subcomponent imperfections on the spectral response of our devices.

Polarization-rotating, Bragg-grating filters on silicon-on-insulator strip waveguides using asymmetric periodic corner corrugations.

We report on a wavelength-selective, polarization-rotating filter using a partially etched asymmetric Bragg grating on a compact single-mode, silicon-on-insulator (SOI) strip waveguide. The asymmetric Bragg grating rotates and reflects the fundamental transverse electric (TE) and transverse magnetic (TM) modes at selected wavelengths. Our device offers wavelength-selective, polarization-rotating reflection at its reflection port and wavelength-selective, polarization-independent notch filtering at its through port.

Grating-assisted silicon-on-insulator racetrack resonator reflector.

We experimentally demonstrate a grating-assisted silicon-on-insulator (SOI) racetrack resonator reflector with a reflect port suppression of 10.3 dB and no free spectral range. We use contra-directional grating couplers within the coupling regions of the racetrack resonator to enable suppression of all but one of the peaks within the reflect port spectrum as well as all but one of the notches within the through port spectrum.

Design of broadband subwavelength grating couplers with low back reflection.

We present a methodology to design broadband grating couplers using one-dimensional subwavelength gratings. Using the presented method, we design subwavelength grating couplers (SWGCs) with 1-dB bandwidths ranging from 50 to 90 nm. Our designed SWGCs have competitive coupling efficiency, as high as -3.

Spiral Bragg grating waveguides for TM mode silicon photonics.

We demonstrate spiral Bragg grating waveguides (BGWs) on the silicon-on-insulator (SOI) platform for the fundamental transverse magnetic (TM) mode. We also compare TM spiral waveguides to equivalent transverse electric (TE) spiral waveguides and show that the TM spiral waveguides have lower propagation losses. Our spiral waveguides are space-efficient, requiring only areas of 131×131 µm(2) to accommodate 4 mm long BGWs, and, thus, are less susceptible to fabrication non-uniformities.

Wavelength tuning and stabilization of microring-based filters using silicon in-resonator photoconductive heaters.

We demonstrate that n-doped resistive heaters in silicon waveguides show photoconductive effects with high responsivities. These photoconductive heaters, integrated into microring resonator (MRR)-based filters, were used to automatically tune and stabilize the filter's resonance wavelength to the input laser's wavelength. This is achieved without requiring dedicated defect implantations, additional material depositions, dedicated photodetectors, or optical power tap-outs.

Process calibration method for designing silicon-on-insulator contra-directional grating couplers.

We present a process calibration method for designing silicon-on-insulator (SOI) contra-directional grating couplers (contra-DCs). Our method involves determining the coupling coefficients of fabricated contra-DCs by using their full-width-at-half-maximum (FWHM) bandwidths. As compared to the null method that uses the bandwidth measured at the first nulls, our FWHM method obtains more consistent results since the FWHM bandwidth is more easily determined.

Experimental demonstration of a silicon-on-insulator high-performance double microring filter using MZI-based coupling.

We have experimentally demonstrated, in silicon, a double microring resonator with Mach-Zehnder interferometer-based coupling that meets many commercial specifications. Our device has a ripple of 0.5 dB, an adjacent channel isolation of at least 41.

Silicon-on-insulator sensors using integrated resonance-enhanced defect-mediated photodetectors.

A resonance-enhanced, defect-mediated, ring resonator photodetector has been implemented as a single unit biosensor on a silicon-on-insulator platform, providing a cost effective means of integrating ring resonator sensors with photodetectors for lab-on-chip applications. This method overcomes the challenge of integrating hybrid photodetectors on the chip. The demonstrated responsivity of the photodetector-sensor was 90 mA/W.