Octave-spanning frequency comb generation in a silicon nitride chip

Abstract

We demonstrate a frequency comb spanning an octave via the parametric process of cascaded four-wave mixing in a monolithic, high-Q silicon nitride microring resonator. The comb is generated from a single-frequency pump laser at 1562 nm and spans 128 THz with a spacing of 226 GHz, which can be tuned slightly with the pump power. In addition, we investigate the RF amplitude noise characteristics of the parametric comb and find that the comb can operate in a low-noise state with a 30 dB reduction in noise as the pump frequency is tuned into the cavity resonance.

New CMOS-compatible platforms based on silicon nitride and Hydex for nonlinear optics

“…Since these initial demonstrations of multiple wavelength oscillation, significant progress has been made in advanced comb generation, including both very wide bandwidth octave spanning combs [66] and very low (sub 100GHz) FSR spacing combs [67].…”

“…Figure 3g shows an optical frequency comb in a SiN ring resonator spanning more than an octave [66] from 1170 to 2350 nm, corresponding to 128 THz. This is achieved by suitable dispersion engineering and employing higher pump powers of up to 400 mW inside the waveguide, detuned slightly from a cavity resonance.…”

“…The last two years have seen significant breakthroughs in understanding the dynamics and coherence behavior associated with frequency comb formation [65][66][67][68][69][70]. These reports have revealed complex and distinct paths to comb formation that can result in widely varying degrees of coherence, wavelength spacing, and RF stability of these sources.…”

Nonlinear optical interactions in silicon waveguides

“…There have been several demonstrations of nonlinear experiments in silicon nitride integrated waveguides and hydex waveguides [14]. Most notably, frequency comb generation [27][28][29][30][31]. However, the nonlinear parameter of such waveguides is relatively small.…”

“…A multitude of linear and nonlinear functions in silicon nitride [14] have been demonstrated. However, most of these, such as supercontinuum generation [24] and comb generation [29,31], have focused on the telecom wavelength band. In addition to this work, a broadband source covering red to near-infrared wavelengths is interesting for biophotonics applications.…”