Longitudinal Multi-Cavity Coupled VCSELs With Narrow Linewidth and High Single Mode Power for Quantum Sensing

We report a novel 795 nm VCSEL with longitudinal three coupled cavity. Because of large increasing the photon lifetime, the spectrum linewidth has been reduced to be 7.3 MHz (limited by the resolution) which is near the natural atomic linewidth. The additional epitaxial cavity spacers yield high diffraction losses for higher order transverse modes. High single mode output power of 4.6 mW was obtained under 25 °C. Rigorous coupled-wave analysis (RCWA) was developed and applied to analyze surface grating. The VCSEL integrated with surface grating remains high orthogonal polarization suppression ratio (OPSR) above 27 dB even at 85 °C, showing excellent polarization stability. The 795 nm high performance VCSELs could play an important role in future generation of high-performance quantum sensing systems.