Abstract:
A laser apparatus has a first mirror, a second mirror, at least a portion of which is defined by the first and second mirrors. The laser has an active region located in the laser cavity, which is capable of stimulated emission at one or more wavelengths of light. The second mirror comprises a plurality of dielectric layers arranged in parallel and having a reflectivity band with a peak reflectivity at a peak wavelength, said reflectivity band having a width of less than 1 nm at a reflectivity of 3 % less than the peak reflectivity. The laser apparatus may be a tunable laser apparatus in which the peak wavelength of the reflectivity band is adjusted, thereby adjusting the lasing wavelength of the laser. The reflectivity band may be a lasing threshold reflectivity band over which the reflectivity of the second mirror is greater than a lasing threshold reflectivity which is sufficient to permit lasing.
Abstract:
A planar lightwave circuit (PLC) module (1220) for conditioning output from a tunable laser (1210) designed to generate light at a target wavelength. The PLC module (1220) has a substrate; a primary waveguide (1221) embedded in said substrate, said primary waveguide (1221) having an input end for receiving light from the tunable laser (1210) and an output end for outputting said light; and at least a first secondary waveguide (1223) embedded in said substrate, said first secondary waveguide (1223) receiving a first portion of said light from said tunable laser (1210). A filter (1227) having a pass band centered on the target wavelength is coupled to an output of the sirst secondary waveguide (1223) to receive said first portion of light, and generates a signal related to the intensity of said first portion of ligth in the pass band centered on the target wavelength. This may be used by a processor (1230) and associated laser control circuitry (1232) for wavelength locking purposes.