Improving far field characteristics of a diode laser array with external cavity

Phase-locking of a diode laser array was achieved in a simple external cavity consisting of a fast axis collimating lens and a high-reflection coated external mirror. When the cavity length is a few centimeter, the far field pattern has 3 lobes, and the divergence of each lobe is about 10 mrad and the contrast of the far field pattern is about 50%. The energy in the side-lobes can be suppressed by blocking the output of some emitters.