Achieving low phase noise in external cavity laser implemented using planar lightwave circuit technology

The present invention relates to external cavity laser (ECL) apparatuses and manufacturing processes, and more particularly to implementing low noise narrow bandwidth ECLs on planar lightwave circuit (PLC) platforms for harnessing high-performance, high-stability operation from a compact-footprint, low-power packaged device. An ECL device with narrow linewidth and low noise is disclosed, the device comprising a PLC device and a gain chip butt-coupled to each other. The PLC device has a planar Bragg grating (PBG) integrated onto a rectangular waveguide. The PLC device has anti-reflection coatings (ARC) on its input facet and output facet. The waveguide is designed to be selective of a single polarization. The gain chip has high-reflection coating (HRC) on a back facet and an ARC on a front facet. An operating wavelength of the ECL is aligned to a longer wavelength red slope of a reflectivity spectrum of the PBG. The operating wavelength may be tuned thermally, electrically, or thermo-electrically.