Whispering gallery germanium-on-silicon photodetector.

We design and demonstrate, to the best of our knowledge, the first whispering gallery germanium-on-silicon photodetector with evanescent coupling from a silicon bus waveguide in a CMOS-compatible process. The small footprint (63.6  μm), high responsivity (∼1.

Ultra-narrow-linewidth AlO:Er lasers with a wavelength-insensitive waveguide design on a wafer-scale silicon nitride platform.

We report ultra-narrow-linewidth erbium-doped aluminum oxide (AlO:Er) distributed feedback (DFB) lasers with a wavelength-insensitive silicon-compatible waveguide design. The waveguide consists of five silicon nitride (SiN) segments buried under silicon dioxide (SiO) with a layer AlO:Er deposited on top. This design has a high confinement factor (> 85%) and a near perfect (> 98%) intensity overlap for an octave-spanning range across near infra-red wavelengths (950-2000 nm).

Wavelength division multiplexed light source monolithically integrated on a silicon photonics platform.

We demonstrate monolithic integration of a wavelength division multiplexed light source for silicon photonics by a cascade of erbium-doped aluminum oxide (AlO:Er) distributed feedback (DFB) lasers. Four DFB lasers with uniformly spaced emission wavelengths are cascaded in a series to simultaneously operate with no additional tuning required. A total output power of -10.

Silicon wavelength-selective partial-drop broadcast filter bank.

We propose an approach to a wavelength-selective 1×N port optical broadcast network demonstrating the approach in a 1×8 port parallel optical drop filter bank utilizing adiabatic micro-ring tunable filters. The micro-ring filters exhibit first-order 92.7±3.

Integrated heterodyne interferometer with on-chip modulators and detectors.

We demonstrate, to our knowledge, the first on-chip heterodyne interferometer fabricated on a 300-mm CMOS compatible process that exhibits root-mean-square (RMS) position noise on the order of 2 nm. Measuring 1 mm by 6 mm, the interferometer is also, to our knowledge, the smallest heterodyne interferometer demonstrated to date and will surely impact numerous interferometric and metrology applications, including displacement measurement, laser Doppler velocimetry and vibrometry, Fourier transform spectroscopy, imaging, and light detection and ranging (LIDAR). Here we present preliminary results that demonstrate the displacement mode.

Generating and identifying optical orbital angular momentum with silicon photonic circuits.

Here, we propose and demonstrate a silicon nanophotonic phased array that is capable of generating light carrying optical orbital angular momentum (OAM). Optical beams carrying different orbital angular momenta have been generated. In addition, the generated OAM wavefronts are experimentally identified by interfering with another on-chip generated Gaussian beam, opening up opportunities of integrating conventional optical systems and functionalities on to a silicon chip.

Integrated phased array for wide-angle beam steering.

We demonstrate an on-chip optical phased array fabricated in a CMOS compatible process with continuous, fast (100 kHz), wide-angle (51°) beam-steering suitable for applications such as low-cost LIDAR systems. The device demonstrates the largest (51°) beam-steering and beam-spacing to date while providing the ability to steer continuously over the entire range. Continuous steering is enabled by a cascaded phase shifting architecture utilizing, low power and small footprint, thermo-optic phase shifters.

Method for characterization of Si waveguide propagation loss.

A new method for measuring waveguide propagation loss in silicon nanowires is presented. This method, based on the interplay between traveling ring modes and standing wave modes due to back-scattering from edge roughness, is accurate and can be used for on wafer measurement of test structures. Examples of loss measurements and fitting are reported.

Graphene-assisted critically-coupled optical ring modulator.

Graphene's conductivity at optical frequencies can be varied upon injection of carriers. In the present paper, this effect is used to modulate losses of an optical wave traveling inside a ring cavity. This way an optical modulator based on the critical-coupling concept first introduced by Yariv can be realized.