Experimental studies of 1.5–1.6 μm high-power single-frequency semiconductor lasers

High-power semiconductor laser systems based on 1.5–1.6 μm single-frequency distributed feedback (DFB) lasers with a sidewall Bragg diffraction grating are developed and their current–voltage, light–current, and spectral characteristics are experimentally studied. The characteristics of conventional lasers with a Fabry–Perot cavity and DFB lasers fabricated from one and the same heterostructure are compared. At a pump current not exceeding 700 mA, a conventional laser with a cavity length of 1.6 mm and a mesa-stripe width of 3 μm emits a power no lower than 200 mW versus 150 mW of the DFB laser; both lasers are mounted in a housing 11 mm in diameter. The DFB laser mounted in a butterfly housing emits a power no lower than 100 mW at the exit of the single-mode cable at a pump current not exceeding 500 mA, which, at a 60% coupling efficiency, corresponds to a power no lower than 165 mW; the side-mode suppression ratio in this case is no lower than 53 dB. It is shown that the wavelength deviation with changing pump current and temperature is almost an order of magnitude lower for the DFB laser than for the conventional laser.