Nanophotonic oscillators for laser conversion beyond an octave

TL;DR

This paper introduces a nanophotonic microresonator-based optical parametric oscillator capable of converting laser frequencies across an octave span, enabling customizable, scalable laser sources for advanced sensing and quantum applications.

Contribution

It demonstrates a novel nanophotonic design that achieves octave-spanning laser frequency conversion through phase matching via nanopatterning, surpassing previous limitations in scalability and tunability.

Findings

Achieved phase matching by nanopatterning to open a photonic-crystal bandgap.

Realized more than 10,000-fold ratio of output frequency span to pump tuning.

Demonstrated fine tuning and minimal frequency noise in laser conversion.

Abstract

Many uses of lasers place the highest importance on access to specific wavelength bands. For example, mobilizing optical-atomic clocks for a leap in sensing requires compact lasers at frequencies spread across the visible and near infrared. Integrated photonics enables high-performance, scalable laser platforms, however, customizing laser-gain media to support wholly new bands is challenging and often prohibitively mismatched in scalability to early quantum-based sensing and information systems. Here, we demonstrate a microresonator optical-parametric oscillator (OPO) that converts a pump laser to an output wave within a frequency span exceeding an octave. We achieve phase matching for oscillation by nanopatterning the microresonator to open a photonic-crystal bandgap on the mode of the pump laser. By adjusting the nanophotonic pattern and hence the bandgap, the ratio of output OPO wave frequency span to required pump laser tuning is more than 10,000. We also demonstrate tuning the oscillator in free-spectral-range steps, more finely with temperature, and minimal additive frequency noise of the laser-conversion process. Our work shows that nanophotonics offers control of laser conversion in microresonators, bridging phase-matching of nonlinear optics and application requirements for laser designs.