0.45 W DIFFRACTION-LIMITED BEAM AND SINGLE-FREQUENCY OPERATION FROM ANTIGUIDED PHASE-LOCKED LASER ARRAY WITH DISTRIBUTED-FEEDBACK GRATING

A second-order diffraction grating placed below the active region of a phase-locked resonant antiguided array selects the in-phase array mod e in addition to its role as a single-longitudinal-mode selector. This type of array-mode discrimination relies on the fact that the resonan t in-phase array mode has significantly better field overlap with the grating region than nonresonant array modes. Furthermore, it eliminate s the need for a conventional array-mode discriminator: interelement l oss; which can cause self-pulsations. Diffraction-limited beam and sin gle-frequency operation is obtained to at least 0.45 W peak pulsed pow er from 20 element, InGaAs/InGaP/GaAs structures (lambda=0.97 mu m) of 120-mu m-wide aperture. Distributed-feedback operation is confirmed o ver the 20-40 degrees C temperature range. The results are in good agr eement with theory. (C) 1998 American Institute of Physics.