Jared Hulme

Widely tunable Vernier ring laser on hybrid silicon

A hybrid silicon tunable Vernier ring laser is designed and fabricated by integration of two intra-cavity ring resonators, hybrid III-V-on-silicon gain elements, and resistive heaters for thermal tuning. Thermal tuning of more than 40 nm is demonstrated with side mode suppression ratio greater than 35 dB and linewidth of 338 kHz.

Heterogeneous Silicon Photonic Integrated Circuits

We review recent breakthroughs in the silicon photonic technology and components, and describe progress in silicon photonic integrated circuits. Heterogeneous silicon photonics has recently demonstrated performance that significantly outperforms native III/V components. The impact active silicon photonic integrated circuits could have on interconnects, telecommunications, sensors, and silicon electronics is reviewed.

Fully integrated hybrid silicon two dimensional beam scanner

In this work we present the first fully-integrated free-space beam-steering chip using the hybrid silicon platform. The photonic integrated circuit (PIC) consists of 164 optical components including lasers, amplifiers, photodiodes, phase tuners, grating couplers, splitters, and a photonic crystal lens. The PIC exhibited steering over 23° x 3.6° with beam widths of 1° x 0.6°.

Fully integrated hybrid silicon free-space beam steering source with 32 channel phased array

Free-space beam steering using optical phased arrays is a promising method for implementing free-space communication links and Light Detection and Ranging (LIDAR) without the sensitivity to inertial forces and long latencies which characterize moving parts. Implementing this approach on a silicon-based photonic integrated circuit adds the additional advantage of working with highly developed CMOS processing techniques. In this work we discuss our progress in the development of a fully integrated 32 channel PIC with a widely tunable diode laser, a waveguide phased array, an array of fast phase modulators, an array of hybrid III-V/silicon amplifiers, surface gratings, and a graded index lens (GRIN) feeding an array of photodiodes for feedback control. The PIC has been designed to provide beam steering across a 15°x5° field of view with 0.6°x0.6° beam width and background peaks suppressed 15 dB relative to the main lobe within the field of view for arbitrarily chosen beam directions. Fabrication follows the hybrid silicon process developed at UCSB with modifications to incorporate silicon diodes and a GRIN lens.

Coupled-Ring-Resonator-Mirror-Based Heterogeneous III–V Silicon Tunable Laser

We show theoretical and experimental results from a tunable laser, with its center wavelength in the C-band, designed using coupled-ring resonator mirrors. The effective cavity length enhancement and negative optical feedback obtained from the resonators helps to narrow the laser linewidth in a small form factor. We report a linewidth of 160 kHz and a side-mode suppression ratio of > 40 dB over the full tuning range.

Heterogeneous Silicon/III–V Semiconductor Optical Amplifiers

We report high output power and high-gain semiconductor optical amplifiers integrated on a heterogeneous silicon/III-V photonics platform. The devices produce 25 dB of unsaturated gain for the highest gain design, and 14 dBm of saturated output power for the highest output power design. The amplifier structure is also suitable for lasers, and can be readily integrated with a multitude of silicon photonic circuit components. These devices are useful for a wide range of photonic integrated circuits. We show a design method for optimizing the amplifier for the desired characteristics. The amplifier incorporates a low loss and low reflection transition between the heterogeneous active region and a silicon waveguide, and we report transition loss below 1 dB across the entire measurement range and parasitic reflection coefficient from the transition below 1 · 10-3.

Narrow linewidth tunable laser using coupled resonator mirrors

A novel fully integrated tunable single mode hybrid silicon laser is demonstrated. We report a linewidth of 260kHz, which is the lowest reported for a monolithically integrated laser. The side-mode suppression ratio is >40dB.

Fully integrated microwave frequency synthesizer on heterogeneous silicon-III/V

We demonstrate a photonic microwave generator on the heterogeneous silicon-InP platform. Waveguide photodiodes with a 3 dB bandwidth of 65 GHz and 0.4 A/W responsivity are integrated with lasers that tune over 42 nm with less than 150 kHz linewidth. Microwave signal generation from 1 to 112 GHz is achieved.

Recent advances in silicon photonic integrated circuits

We review recent breakthroughs in silicon photonics technology and components and describe progress in silicon photonic integrated circuits. Heterogeneous silicon photonics has recently demonstrated performance that significantly outperforms native III-V components. The impact active silicon photonic integrated circuits could have on interconnects, telecommunications, sensors and silicon electronics is reviewed.

A Robust Method for Characterization of Optical Waveguides and Couplers

We propose a simple yet powerful method to characterize waveguide propagation loss and 2 × 2 waveguide couplers coupling coefficient simultaneously. The method, based on the spectrum analysis of transmission through an unbalanced Mach-Zehnder interferometer, requires only a single test structure and is insensitive to variation of input coupling losses. We show that, in most general cases, it is possible to determine both the propagation loss and the coupling of both couplers that can have different coupling coefficients.