# Efficient telecom-to-visible spectral translation through ultra-low power nonlinear nanophotonics

## TL;DR

This paper demonstrates a highly efficient, low-power spectral translation device using third-order nonlinear nanophotonics in silicon nitride resonators, enabling bridging telecom and visible wavelengths with unprecedented efficiency.

## Contribution

The work introduces a novel approach using third-order nonlinear systems with resonant enhancement for spectral translation, surpassing previous second-order methods in efficiency and power consumption.

## Key findings

- Achieved 30.1% translation efficiency at low pump power
- Demonstrated spectral translation over >250 THz range
- Projected efficiency exceeds 270% at 1 mW pump power

## Abstract

The ability to spectrally translate lightwave signals in a compact, low-power platform is at the heart of the promise of nonlinear nanophotonic technologies. For example, a device to link the telecommunications band with visible and short near-infrared wavelengths can enable a connection between high-performance chip-integrated lasers based on scalable nanofabrication technology with atomic systems used for time and frequency metrology. While second-order nonlinear (\chi^(2)) systems are the natural approach for bridging such large spectral gaps, here we show that third-order nonlinear (chi^(3)) systems, despite their typically much weaker nonlinear response, can realize spectral translation with unprecedented performance. By combining resonant enhancement with nanophotonic mode engineering in a silicon nitride microring resonator, we demonstrate efficient spectral translation of a continuous-wave signal from the telecom band (~ 1550 nm) to the visible band (~ 650 nm) through cavity-enhanced four-wave mixing. We achieve such translation over a wide spectral range >250 THz with a translation efficiency of (30.1 +/- 2.8) % and using an ultra-low pump power of (329 +/- 13) uW. The translation efficiency projects to (274 +/- 28) % at 1 mW and is more than an order of magnitude larger than what has been achieved in current nanophotonic devices.