Widely tunable photonic crystal lasers

We fabricate tunable semiconductor lasers with two coupled photonic crystal cavities that allow up to 46 nm tuning range with a side-mode suppression ratio greater than 30 db. The effect of design parameters on device performances is discussed. In particular, we demonstrate that the lattice parameter of photonic crystals and the dimensions of the coupled cavities are the key parameters. On the basis of tuning curves, we also explain the tuning mechanisms and the guidelines for improving laser performance. Finally, we present a laser that enables tuning on three coarse wavelength dense multiplexing (WDM) channels.