Efficient diffraction-limited beam combining of semiconductor laser diode arrays using photorefractive BaTiO3

Beam combining of 820-nm-wavelength laser diodes using two-wave mixing in BaTiO3 is reported. Energy transfer efficiencies up to 80 percent were obtained with an index-guided diode. Efficient beam combining of two injection-locked laser arrays was demonstrated. Nearly 100 mW power in a diffraction-limited beam was obtained on the combined beam. Crystal response time on the order of a few seconds was measured. It is noted that this technique could prove very useful for phase-locking and combining very high-power laser diode arrays such as laser bars or surface emitting arrays, or independent lasers widely separated from each other. (I.E.)