William Walter Simmons

Design considerations for diffraction coupled arrays with monolithically integrated self‐imaging cavities

Conditions for stabilization of in‐phase or out‐of‐phase array eigenmodes in diffraction coupled diode laser arrays are derived and applied to several array architectures. The analysis predicts that the discrimination between these two eigenmodes is strongest in arrays with half Talbot distance long free‐propagation region. In this geometry, the out‐of‐phase and in‐phase near fields are, respectively, reproduced and channeled halfway between the original channel locations.

Coherent operation of injection-locked monolithic surface-emitting diode laser arrays

A row of six surface‐emitting GaAlAs laser diode arrays was locked in a coupled resonator configuration by means of interconnecting waveguides. An external master oscillator was injected into the first array in order to achieve single longitudinal mode operation and wavelength tunability. Spectral data show all six devices were locked in a single longitudinal mode, with tunable operation of over 60 A. Far‐field fringe visibilities greater than 60% were achieved at 100 mW output powers.

Supermode discrimination in diffraction‐coupled laser arrays with separate contacts

We show that in‐phase lasing is favored in diffraction‐coupled arrays with separate electrical contacts for the common unguided diffraction zone and for the waveguide section, if the common unguided section is biased above a critical level. Below that level, out‐of‐phase lasing will be favored. By varying the current about the critical level, the far‐field intensity switches from a wide far‐field pattern characterized by the admixture of several supermodes, to a near‐diffraction‐limited single peak.

Supermode selection in diffraction‐coupled semiconductor laser arrays

A modal gain analysis for diode laser diffraction‐coupled arrays which takes into account evanescent coupling in the waveguide section of an array is presented. Theoretical predictions are supported by comparisons of patterns from typical double‐heterostructure and large‐optical‐cavity lasers.

High average power frequency doubling

High average power second harmonic generation in crystals with finite absorption at the fundamental or harmonic wavelength creates unique problems. In addition to generating significant OPD which degrades the beam quality, heating of the crystal creates conditions which can be inherently temporally unstable. As the crystal is tuned towards phase matching, rapid changes in temperature cause the crystal to drift away from phase matching conditions which is followed by reduced frequency conversion. Experiments are in progress with three crystals, KTP, KD*P and KNbO/sub 3/, which have vastly different characteristics, to assess their potential for high average power doubling.<<ETX>>