Abstract: A device includes a multiple-wavelength (e.g., dual wavelength) vertical-cavity surface-emitting laser (VCSEL) array including a first VCSEL set including one or more first VCSEL to emit first VCSEL radiation at a first wavelength, and a second VCSEL set including one or more second VCSEL to emit second VCSEL radiation at a second wavelength different than the first wavelength. The device includes upstream optics to upstream optics to (a) collimate the first VCSEL radiation emitted by the first VCSEL set and (b) collimate the second VCSEL radiation emitted by the second VCSEL set. The device also includes a vapor cell to receive the collimated first VCSEL radiation and the collimated second VCSEL radiation and to provide an output beam as a function of the received collimated first VCSEL radiation and collimated second VCSEL radiation, and measurement circuitry to analyze the output beam provided by the vapor cell.