High-power continuous-wave operation of a fiber optical parametric oscillator in L and U bands

Fiber optical parametric oscillators (OPOs), based on a highly-efficient four-wave mixing process in a chi((3)) medium, are reviewed. Their capability to provide very large tuning ranges with high output power is discussed. A novel architecture for CW fiber OPOs is presented, which has allowed us to significantly extend the performance of these devices. To do so we used: (i) a highly-nonlinear fiber (HNLF) as the parametric gain medium; (ii) a narrowband tunable intracavity filter; (iii) a high output coupling fraction from the feedback loop (up to 3 dB). With these features, we have been able to obtain excellent performance in terms of output power and tuning range, even with a reduced pump power. With only about 2 W of pump power, we have obtained the following performances: (i) tuning range of 254 nm; (ii) output power in excess of 1 W at some wavelengths; (iii) external conversion efficiency in excess of 60% at some wavelengths; (iv) linewidth as low as 8 GHz. This architecture of fiber OPO can be used for providing narrow linewidth tunable high-power CW radiation over hundreds of nanometers. Such sources could find applications in remote sensing, optical communication, nonlinear optics, etc