Ultrafast watt-level fiber-feedback multipassoptical parametric oscillator

Optical parametric oscillators are widely used and versatile sources due to their ability to generate broadly tunable ultrashort pulses over a large spectral range. One practical limitation is the optical parametric single-pass gain in nonlinear crystal, which often requires post amplification stages for power scaling. In this Letter, we present the implementation of a high gain multipass optical parametric oscillator in a fiber-feedback cavity to form a tunable single-stage pulse source. The OPO is tunable from 1.4 μm-1.85 μm with 100 fs pulses and watt-scale average powers at a repetition rate of 76 MHz. Furthermore, we demonstrate shot-noise limited performance. This system, not requiring additional amplification or compression stages, can significantly reduce the size and cost of tunable ultrashort-pulse sources for spectroscopy and bioimaging applications.