Measurement and numerical analysis of intrinsic spectral linewidths of photonic-crystal surface-emitting lasers

Photonic-crystal surface-emitting lasers (PCSELs) feature high-power coherent lasing over a large area, which are potentially suitable for various applications requiring narrow spectral linewidths. In this paper, we experimentally and theoretically investigate intrinsic spectral linewidths of PCSELs. We first measure the frequency noise spectra of a fabricated PCSEL with a 250-μm lasing diameter and realize single-mode lasing with an intrinsic spectral linewidth below 70 kHz. To investigate the feasibility of narrower spectral linewidths in PCSELs, we next perform the theoretical analysis of intrinsic spectral linewidths of PCSELs by a time-dependent three-dimensional coupled-wave analysis considering carrier–photon interactions as well as thermal effects. We reveal that intrinsic spectral linewidths below 1 kHz can be obtained with a 500-μm-diameter PCSEL by reducing the cavity loss and by compensating the temperature-induced band-edge-frequency distribution.