Abstract

Phase-locked laser combining systems using intracavity holograms, spatial filters, or beam splitters are shown to be mathematically equivalent and to provide strong phase-locking by providing a minimum loss for in-phase cooperation. Our model accurately predicts the combinations of diode laser currents required by a multidiode laser system to achieve threshold. This model also correctly predicts the parabolic increase in optical power emitted at the phase canceled port as a function of the diode lasers’ drive current imbalance. The automatic phase adjustments needed for efficient power collection, which are produced by small changes in the optical frequency, are shown to be greatly augmented by increasing the mismatch in cavity lengths among the various laser arms of the compound cavity. This cavity design guarantees efficient power collection independent of pathlength changes along the laser arms. A real-time measurement of the self-locked phase error is also shown to decrease for narrow spectral behavior and increase for broadband lasing.

© 1991 Optical Society of America