Study of the Dynamics of a High-Energy Normal-Dispersion Fiber Optical Parametric Chirped-Pulse Oscillator

The growing use of nonlinear imaging and spectroscopy - namely multiphoton imaging and coherent Raman spec-troscopy - has led to the development of a myriad of ultra-short, tunable, and energetic light sources, mostly based on second-order nonlinear frequency conversion in bulk materials, with outstanding achievements in terms of energy, peak power, and stability [1]. Although these sources fully satisfy the requirements for nonlinear imaging [2], they require high maintenance, limiting their use to a controlled environment. Fiber-based sources then appear as a solution to bring these experiments outside the lab, but are limited to biological tissue imaging be-cause of their limited pulse energy. To expand nonlinear imaging techniques to diluted media (e.g. gases), the approach of combining chirped pulse amplification with four-wave mixing in optical fibers to enhance pulse en-ergy has proven effective, as demonstrated by the recent realization of a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{J}$</tex> -level fiber optical parametric oscillator (FOPCPO) pumped with highly chirped pulses [3]. Furthermore, this FOPCPO concept enables improved control of the generated bandwidth by adjusting the relative chirp of the pump and the resonant wave [4]. In this work, we investigated the dynamics of such a FOPCPO to verify its ability to meet the low-noise and high-stability require-ments of nonlinear imaging. In addition, we confirmed that parametric oscillators provide a more stable pulse train compared to parametric amplifiers [5].