Ultra-bandwidth femtosecond optical parametric oscillator based on intracavity broadband laser gain

Synchronously pumped optical parametric oscillators (OPOs) can generate ultrashort pulses with extremely broad tuning range. However, in conventional OPO, the output bandwidth generally is constrained by phase-matching and pump bandwidth, it greatly restricted the potential for shorter pulse durations. Here, we propose and demonstrate a synchronously pumped femtosecond OPO combined with intracavity broadband laser gain. Tunable laser pulses covering 680–920 nm with a maximum bandwidth of 95 THz at -20 dB was realized by using both BIBO and Ti:S gain media within the same cavity. The maximum bandwidth corresponding to the Fourier transform-limit (FTL) pulse duration of 9.8 fs, typical average output power is 430 mW. To the best of our knowledge, this result represents the broadest bandwidth output from a femtosecond OPO at a power of 100 mW level. Beyond the Ti:S gain medium demonstrated here, this scheme can be extended to the mid‑infrared band using other gain media, offering a promising route to the challenge of mode locking in mid‑infrared lasers. The performances are promising for wide applications in ultrafast spectroscopy and photobiology.