Low noise planar external cavity laser for interferometric fiber optic sensors

A 1550 nm DWDM planar external cavity laser is demonstrated to provide low phase / frequency noise and narrow linewidth. The cavity includes a semiconductor gain chip and a planar lightwave circuit waveguide with Bragg grating, packaged in a 14-pin butterfly package. The laser shows linewidth < 30 kHz and phase/frequency noise comparable with that of long cavity fiber lasers. Performance is suitable for various fiber optic sensing systems, including interferometric sensing in Oil and Gas, military/security and other applications, currently served mostly by costly and less reliable laser sources.