Widely tunable frequency doubled light source

Abstract

A widely tunable frequency doubled light source includes a fundamental widely tunable laser emitting fundamental radiation tuned over a fundamental wavelength range and a broadband nonlinear waveguide which frequency doubles the fundamental radiation over a frequency doubled wavelength range. A preferred implementation of the widely tunable laser is a MEMS-VCSEL followed by a semiconductor optical amplifier. Preferred implementations of the nonlinear waveguide include periodically poled lithium niobate with various means for broadening a conversion bandwidth, including dispersion engineering to reduce a group velocity mismatch between fundamental and frequency doubled wavelengths and employing a chirped poling period. Various optical systems are enabled by this new frequency doubled light source, including swept source optical coherence tomography (SSOCT) at previously inaccessible wavelength ranges, such as in the green/yellow gap range from about 500 nm to about 600 nm. Other optical systems enabled by the widely tunable frequency doubled light source include systems for optical spectroscopy, beam steering, Raman spectroscopy, and wavelength division multiplexed optical communications.