Mid-infrared photonic-crystal distributed-feedback laser with enhanced spectral purity and beam quality

We report a photonic-crystal distributed-feedback (PCDFB) laser with an antimonide type-II "W" active region. Optical lithography and dry etching were used to pattern the two-dimensional rectangular lattice with a second-order grating tilted by 20 degrees relative to the facet normal. For pulsed optical pumping, the emission line centered on lambda =4.6-4.7 mum is considerably narrower (7-10 nm) than for Fabry-Perot and angled-grating DFB (alpha -DFB) lasers fabricated from the same wafer. The PCDFB beam quality is also substantially enhanced, e.g., by a factor of 5 compared with the alpha -DFB at a pump-stripe width of 200 mum. (C) 2001 American Institute of Physics.