Spectral Linewidth of Photonic Crystal Surface Emitting Lasers

The spectral linewidth of photonic crystal surface emitting lasers is evaluated using a heterodyne method utilizing two nominally identical devices. Linewidths of 100–200 kHz are obtained at modest output powers for these GaAs based 935 nm PCSELs. The natural linewidth is determined to be
$71\pm 30 \ \text{kHz}$
.