| Popis: |
While considerable attention has rightly been paid to the spatial coherence properties of high-power semiconductor lasers, very little work has been done to optimize their temporal coherence, as might be required by applications such as pulsed-Doppler laser radar, widespread optical clock distribution in dispersive channels, and spectroscopy. Here we describe the operation of a wide stripe GRIN-SCH-SQW laser in external cavities. A high-reflectivity coating ( R - 85 %) was deposited on one side and a anti-reflection coating (R < 1%) was deposited on the other (internal) facet. A simple mirror external cavity gave maximum threshold reduction (to the original threshold current) but the longitudinal mode spectrum was broad and unstable. By contrast, when a diffraction grating was used as the external reflector, the laser operated up to at least 2.5 'th in a single, < 0.5 A, instrument limited longitudinal mode which was tunable over more than 300 A. Using this configuration the laser produced more than 500 mW in pulsed mode. The output wavelength was extremely stable with respect to variations in current and temperature. |
