Austin G. Griffith

Silicon-Chip Mid-Infrared Frequency Comb Generation

We report the first on-chip integrated mid-infrared frequency comb using a silicon optical parametric oscillator ring resonator. We demonstrate a 750-nm-wide comb centered at 2.6 um.

Mode-locked mid-infrared frequency combs in a silicon microresonator

We demonstrate a near-octave spanning and soliton modelocked mid-infrared frequency comb in a silicon microresonator. The soliton state can be accomplished via either pump laser detuning or electrical tuning of the free-carrier lifetime.

Linearized silicon modulator based on a ring assisted Mach Zehnder inteferometer

We demonstrate a Linearized Ring Assisted Mach-Zehnder Interferometer (L-RAMZI) modulator in a miniature silicon device. We measure a record high degree of linearization for a silicon device, with a Spurious Free Dynamic Range (SFDR) of 106dB/Hz²/³ at 1GHz, and 99dB/Hz²/³ at 10GHz.

Breather soliton dynamics in microresonators

The generation of temporal cavity solitons in microresonators results in coherent low-noise optical frequency combs that are critical for applications in spectroscopy, astronomy, navigation or telecommunications. Breather solitons also form an important part of many different classes of nonlinear wave systems, manifesting themselves as a localized temporal structure that exhibits oscillatory behaviour. To date, the dynamics of breather solitons in microresonators remains largely unexplored, and its experimental characterization is challenging. Here we demonstrate the excitation of breather solitons in two different microresonator platforms based on silicon nitride and on silicon. We investigate the dependence of the breathing frequency on pump detuning and observe the transition from period-1 to period-2 oscillation. Our study constitutes a significant contribution to understanding the soliton dynamics within the larger context of nonlinear science.

Coherent mid-infrared frequency combs in silicon-microresonators in the presence of Raman effects

We demonstrate the first low-noise mid-IR frequency comb source using a silicon microresonator. Our observation of strong Raman scattering lines in the generated comb suggests that interplay between Raman and four-wave mixing plays a role in the generated low-noise state. In addition, we characterize, the intracavity comb generation dynamics using an integrated PIN diode, which takes advantage of the inherent three-photon absorption process in silicon.

Competition between Raman and Kerr effects in microresonator comb generation

We investigate the effects of Raman and Kerr gain in crystalline microresonators and determine the conditions required to generate mode-locked frequency combs. We show theoretically that a strong, narrowband Raman gain determines a maximum microresonator size allowable to achieve comb formation. We verify this condition experimentally in diamond and silicon microresonators and show that there exists a competition between Raman and Kerr effects that leads to the existence of two different comb states.

Mid-infrared supercontinuum generation in silicon waveguides

We demonstrate supercontinuum generation (SCG) spanning from telecom to mid-infrared wavelengths beyond 3.6 μηι, using a silicon-on-insulator wire waveguide, which represents the first octave-spanning SCG from a silicon chip.

Breather Solitons in Microresonators

We present the first observations of breather solitons in microresonators. Our results provide key insight into the evolution towards stable soliton formation in microresonator-based frequency combs.

Parametric frequency conversion in silicon carbide waveguides

We show the first demonstration of frequency conversion via four wave mixing in a silicon carbide channel waveguide with a conversion efficiency as high as -19.5 dB over a 180 nm wavelength range.

Low-noise silicon mid-infrared frequency comb

We demonstrate low-noise mid-infrared frequency comb generation using a silicon microresonator. Using an integrated PIN-diode detector, we show a transition to a low RF-amplitude-noise state consistent with demonstrations of phase-locking in other microresonator platforms.