Kerr-Lens Modelocked Non-Collinear Optical Parametric Oscillator
The KLM-NOPO is a specific type of non-collinear optical parametric oscillator (NOPO) that uses broadband amplification to generate even shorter pulse durations. Generally, NOPOs are constrained by the pulse duration of their pump source, as efficient amplification occurs only when the duration of the amplified pulse is close to that of the pump pulse. To overcome this limitation, the KLM-NOPO employs a "breathing" pulse mode-locking technique. In this approach, the pulse duration changes during each cavity round-trip, aligning with the pump pulse duration during amplification. This technique allows for the emission of very short pulses from the laser. Due to the parametric nature of the amplification no additional cooling is needed which makes this source intrisically power scalable ( https://doi.org/10.1364/CLEO_SI.2021.STu4C.4).
Doubly Resonant Optical Parametric Oscillator
Doubly resonant optical parametric oscillators (DROPOs) are versatile sources for generating ultrafast pulses at wavelengths that are not easily reached with conventional laser gain media. By resonating both signal and idler waves, DROPOs achieve high conversion efficiency and exhibit a remarkably low pump threshold, making them highly attractive for quantum optics and spectroscopy. In our laboratory, we have realized a high-power 2-µm phase-locked femtosecond source based on a BBO-cystal DROPO [1], synchronously pumped by a home-built Yb:YAG Kerr-lens mode-locked thin-disk laser. A dither-free stabilization scheme is employed, where an intracavity “parasitic” sum-frequency of signal and pump seerves as an error signal to maintain stable degeneracy operation. With 15.8 W of pump power, the systm delivers 5.6 W output power at 2 µm with a conversion efficiency of 35%. Long-term operation over 90 minutes shows an RMS power noise of 0.78%, demonstrating excellent stability and reliable performance.
References:
1. C. M. Dietrich, I. Babushkin, J. R. C. de Andrade, H. Rao, A. Demircan, and U. Morgner, “Higher-order dispersion and the spectral behavior in a doubly resonant optical parametric oscillator,” Opt. Lett. 45, 5644–5647309 (2020). DOI 10.1364/OL.440840
