A highly reliable, very low-phase and low-amplitude-noise laser is required as an oscillator for the LISA mission. A commercial product made by Redfern Integrated Optics met these requirements (1550 nm PLANEX External Cavity Laser), but it operated at 1.5 microns, not the required LISA wavelength of 1 micron. An ultra-low-noise External Cavity Laser was produced at a wavelength of 1 micron, and was integrated in a butterfly package. The goal is to eventually use this laser in the LISA and GRACE-II missions.
PLANEX (Planar External Cavity Laser) contains a gain chip (GC) and planar lightwave circuit (PLC) with Waveguide Bragg Gratings (WBGs). To enable the wavelength change to 1 micron in the proven high-reliability PLANEX design and packaging technology, a new GC was developed with low-frequency noise and optimized mode profile for high coupling efficiency with the PLC waveguide. A new GC ultra-low-reflectivity coating was developed to suppress the GC cavity. In addition, a new WBG reflector was developed for a wavelength of 1 micron, and a new 1-micron WBG manufacturing process was developed for a short grading period and optimized etch depth.
The new product is the first External Cavity Laser that fits in a butterfly package and operates at 1-micron wavelength. With its low noise performance and 1-micron wavelength, it can eventually be used as the oscillator for the LISA and GRACE-II missions, although some work remains to optimize its design and further lower frequency noise.
Commercial applications include use as a seed laser for high-power fiber lasers (MOPAs) for materials processing and scientific applications.