Grating-based red lasers

We have demonstrated a number of high power and single-frequency lasers at 635-680nm by incorporating a grating reflector within the device, including DBRs, tunable DBRs, monolithic MOPAs, DFBs, and angled-grating DFBs. The DBR laser, with an unpumped grating as the rear reflector, is the simplest single-frequency structure, with about 20mW output power. The device can be tuned about 3nm by injecting current in the rear grating. Higher output power can be obtained by combining the DBR with a flared amplifier to form a monolithic MOPA with over 250mW CW output power. Unlike DBR structures, the DFBs have a grating throughout their gain region, and therefore show no mode hops. Wavelengths as short as 634nm and output powers as high as 90mW have been obtained with DFBs. An angled-grating DFB is a broad area device where the angled grating forces lasing in a single spatial and longitudinal mode. More than 400mW in single-frequency power has been obtained at 660nm from such a structure. In general, grating-based red lasers are useful for interferometry, spectroscopy, and fiber-coupling applications.