Polarization control by modulated photonic-crystal lasers

Modulated photonic-crystal lasers can control the output beam direction two-dimensionally by exciting a two-dimensional cavity mode at the non-diffractive photonic band-edge and diffracting the mode upwards with position modulation of each air hole. In these lasers, the position modulation can be introduced one-directionally, where the modulation is given by the distances between the air holes, or two-directionally, where the modulation is given by the rotation angles of the air holes. For one-directional position modulation, we show that the polarization of output beams is perpendicular to the direction of modulation. For two-directional position modulation, we show that circularly polarized beams are obtained. As such, these lasers can control not only the beam direction but also the polarization.