A narrow-linewidth three-mirror VCSEL for atomic devices

Abstract

We consider the use of a recently invented three-mirror vertical-cavity surface-emitting laser (VCSEL) as an optical-pumping light source for next-generation atomic devices (e.g., atomic clocks). While VCSELs are attractive given their very low size, weight, and power and intrinsic resistance to longitudinal mode hops, their relatively large linewidths give rise to efficient laser phase-noise to transmitted intensity noise conversion (PM-to-AM), which severely limits the signal-to-noise ratio in vapor-cell signals. In contrast, the three-mirror VCSEL has a linewidth more than ten times narrower than traditional VCSELs. Using a three-mirror VCSEL in a continuous-wave Cs vapor-cell atomic clock testbed, we demonstrate the utility of this laser for next-generation atomic devices in general, obtaining a short-term stability of 3.6 × 10−12/τ1/2 without any attention to PM-to-AM mitigation strategies.