Widely Tunable All-Fiber Optical Parametric Oscillator Seeded by Ultrashort Pulses at Fixed Central Wavelength

Although Four-Wave Mixing (FWM) has been extensively investigated, recent advancements in nonlinear imaging and spectroscopy have renewed interest in this area. This resurgent focus is driven by the need for ultrashort pulses at specific wavelengths, essentially for deep-tissue imaging and matching the spectral response of fluorophores and molecular vibrations [1]. FWM provides wide and selective wavelength tunability with high power, particularly in resonant cavity configuration. Fiber optical parametric oscillators (FOPOs) based on FWM demonstrate broad tunability by varying the wavelength of the pump beam from tunable ultrafast fiber oscillators [2]. However, most commercially available mode-locked fiber lasers have fixed or slightly tunable wavelengths.