STEP-TUNABLE EXTERNAL-CAVITY SURFACE-EMITTING SEMICONDUCTOR LASER

摘要

A laser for delivering laser radiation at a selected one of a plurality of equally-spaced frequencies extending over a frequency range includes a laser resonator defined by two end mirrors. The resonator includes a surface-emitting semiconductor multilayer gain-structure in optical contact with one of the mirrors. A third mirror located in the laser resonator forms an etalon with that mirror. The third mirror is movable for adjusting a peak transmission frequency of the etalon to align with the selected frequency. The resonator end mirrors are spaced apart by an optical distance selected such that the frequency and frequency-spacing of possible longitudinal lasing modes of the resonator correspond with the plurality of equally-spaced frequencies. When the peak transmission frequency of the etalon is aligned with the selected frequency the laser resonator delivers radiation in a single longitudinal mode at the selected frequency.