Highly-efficient generation of coherent light at 2128 nm via degenerate optical-parametric oscillation

TL;DR

This paper demonstrates a highly efficient method to generate coherent light at 2128 nm using a degenerate optical parametric oscillator, enabling effective wavelength conversion from existing laser sources for advanced gravitational-wave detectors.

Contribution

The authors develop a degenerate optical parametric oscillator achieving 88.3% efficiency at 2128 nm, facilitating efficient wavelength conversion from 1064 nm lasers with high stability.

Findings

Achieved 88.3% external conversion efficiency at 2128 nm

Demonstrated effective non-linearity of 4.75 pm/V in PPKTP

Enabled efficient wavelength conversion from 1064 nm to 2128 nm

Abstract

Cryogenic operation in conjunction with new test-mass materials promises to reduce the sensitivity limitations from thermal noise in gravitational-wave detectors. The currently most advanced materials under discussion are crystalline silicon as a substrate with amorphous silicon-based coatings. They require, however, operational wavelengths around 2 $\mathrm\mu$m to avoid laser absorption. Here, we present a light source at 2128 nm based on a degenerate optical parametric oscillator (DOPO) to convert light from a 1064 nm non-planar ring-oscillator (NPRO). We achieve an external conversion efficiency of $(88.3\,\pm\,1.4)\,\%$ at a pump power of 52 mW in PPKTP (periodically-poled potassium titanyl phosphate, internal efficiency was 94 %), from which we infer an effective non-linearity of $(4.75\,\pm\,0.18)\,\mathrm{pm/V}$. With our approach, light from the established and existing laser sources can be efficiently converted to the 2 $\mathrm\mu$m regime, while retaining the excellent stability properties.