We present a simple method for mid-infrared optical frequency comb generation based on singlepass femtosecond optical parametric generation that is seeded by a continuous-wave laser. We have implemented the method in a periodically poled lithium niobate crystal that produces a frequency comb tunable across 3325 -4000 nm (2380 -3030 cm -1 ). The method generates a midinfrared (idler) comb with known and stabilized Carrier-Envelope Offset (CEO) frequency without the need to directly detect it. The idler CEO is continuously tunable for almost half of the repetition rate and can be modulated, while maintaining its central frequency. Together with the high output power (up to 700 mW) and low intensity noise (0.018% integrated in 10 Hz -2 MHz bandwidth) this makes the demonstrated mid-infrared frequency comb promising for applications that require precise CEO control, such as dual-comb spectroscopy, cavity enhanced spectroscopy and high harmonic generation.

In the present paper, we investigate a special type of optical coupling between two electrically pumped semiconductor whispering gallery mode lasers. We fabricate microdisk lasers with a conjunction between the laser cavities, making the coupling stronger. Our experimental results combined with numerical calculations demonstrate a variety of mode families that exist in such systems. Furthermore, we confirm the generation of resonance modes that exist only under simultaneous pumping conditions. These modes are attributed to the collective mode family, which can lead to a single mode operation.

This study proposes and demonstrates a versatile method for near- and mid-infrared optical frequency comb generation using multi-seeded femtosecond optical parametric generation. The method allows one to divide the repetition rate by an arbitrarily large integer factor, freely tune the offset frequency, and adjust the common phase offset of the comb modes. Since all possible degrees of freedom are adjustable, the proposed method manifests itself as versatile optical frequency synthesis.

We demonstrate an approach for mid-infrared frequency comb generation based on femtosecond Optical Parametric Generation seeded by a continuous-wave laser. The offset frequency can be stabilized, continuously tuned and modulated without its direct detection.