VCSELs for quantum sensing with Rubidium

As quantum sensing technology reaches the level of maturity and bio- and navigation sensors begin to enter the market, the demand for affordable, compact light source operating at alkali atom wavelengths is peaking. For sensors based on rubidium, the operational wavelengths are targeted at the D1 (795nm) and D2 (780nm) transitions. Applications where the light source power requirements is around 1mW, such as vapor cell magnetometers, vertical-cavity surface-emitting lasers (VCSELs) operating on 7xx nm range are attractive solutions due to their small size, low power consumption and low temperature sensitivity. Moreover, the polarization control and linewidth of VCSELs can be tailored by epitaxial design and/or manufacturing process to meet all other application-specific requirements. In this paper, we present our 780nm and 795nm VCSELs key characteristics produced at Modulight. We have developed wafer level manufacturing processes, utilizing highly uniform oxidation process to maintain single-mode operation, and surface grating fabrication polarization control. The wafer level testing results are compared with those from on chip-on-submount. The effect of different designs and fabrication options on productivity and yield is also discussed.