Generation of vector beams by spatially modulated photonic-crystal lasers

Laser beams with spatially controlled cross-sectional polarization distributions, called vector beams, have attracted much attention for their ability to be focused to dimensions below the diffraction limit. Here, we realize a single-chip vector beam generator that does not require any external optical elements. This generator consists of modulated photonic-crystal lasers (M-PCSELs) whose photonic-crystal lattice-point positions are spatially modulated to produce vertical diffraction of the two-dimensional lasing mode with various polarization distributions. By designing the modulation, we show that M-PCSEL can generate arbitrary cylindrically polarized vector beams.