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Towards self-referencing of a VECSEL frequency comb

Optical frequency combs from ultrafast lasers have revolutionized the field of optical metrology and photonics. However, today's commercial frequency combs are still based on complex and expensive ultrafast laser systems, which prevent applications for cost-sensitive areas. Among emerging technologies, modelocked semiconductor lasers are highly promising for future low-cost high-volume production owing to the benefits of semiconductor manufacturing. Vertical external-cavity surface-emitting lasers (VECSELs) are one of the most promising technologies for this purpose. However, the carrier-envelope offset (CEO) frequency of an ultrafast VECSEL has never been stabilized yet because of the demanding combination of high peak power and short pulse duration required for the generation of a coherent, octave-spanning supercontinuum (SC) spectrum for CEO detection. In 2014, the first CEO beat signal from a VECSEL has been recorded after external pulse amplification and compression, but a high noise prevented a detailed analysis and stabilization [1]. In 2016, we presented the first characterization of the noise properties and modulation response of a VECSEL CEO frequency based on an indirect method using a beating signal with an auxiliary continuous-wave laser [2].