AlGaInP-based VECSEL for strontium clock transitions

Red-emitting optically-pumped vertical-external-cavity surface-emitting-lasers (VECSELs) are an interesting platform for compact, low noise, and high spatial and spectral brightness laser systems targeting narrow linewidth transitions used in strontium-based optical clocks. Recently, we have demonstrated sub-kHz linewidth operation at 689 nm when pumped by either green or blue lasers. Here we report the development and characterisation of an AlGaInP-based VECSEL targeting ionic and neutral strontium-based optical clock transitions at 674 and 698 nm, respectively. Both systems have single frequency output powers >100 mW in a circularly-symmetric transverse mode, achieving sub-200 Hz linewidth with low-loss, single-stage frequency-stabilisation.