Watt-level widely tunable femtosecond mid-infrared KTiOAsO₄ optical parametric oscillator pumped by a 103  μm Yb:KGW laser

Abstract

A high-power, high-repetition-rate, broadband tunable femtosecond optical parametric oscillator (OPO) is constructed based on KTiOAsO crystal, pumped by a 75.5 MHz mode-locked Yb:KGW laser. With 7 W pump power, the OPO generates as much as 2.32 W of signal power at 1.55 μm and 1.31 W of idler power at 3.05 μm, corresponding to a total conversion efficiency of 51.8%. Operating at 151 MHz repetition rate, the wavelength of the signal covers 1.41-1.71 μm with a tunable idler range of 2.61-3.84 μm. The idler bandwidth is more than 180 nm over the entire mid-infrared range. By compensating intracavity dispersion, the signal pulse has a nearly Fourier transform-limited duration of 129 fs at 1.52 μm.

Mode-locked 2.8-μm fluoride fiber laser: from soliton to breathing pulse

“…The breathing-pulse MLFFL produced a pulse energy of 9.3 nJ and a pulse duration of 215 fs with a record peak power of 43.3 kW, which reaches the level of state-of-the-art mid-IR femtosecond optical parametric oscillators in the spectral region around 3 μm. 20,21 This work paves the way for the pulse-energy and peak-power scaling of mid-IR MLFFLs.…”

Tunable Mid‐Infrared Detail‐Enhanced Imaging With Micron‐Level Spatial Resolution and Photon‐Number Resolving Sensitivity

“…Accordingly, our MIR imaging system can maintain a large 2D SBP of ≈62 900 from 2.0 to 3.0 µm. Here, for the spectral zone beyond 3 µm, MIR imaging can also be available by just using other nonlinear crystals, for example, KTA (KTiOAsO 4 ) crystal, [ 41 ] instead of the β ‐BBO crystal, if necessary.…”

High power, widely tunable femtosecond MgO:PPLN optical parametric oscillator

“…Compared to the widely tunable femtosecond OPO by tuning crystal angle, the output power can be scaled significantly at different central wavelengths with QPM MgO:PPLN crystal. [21] In addition, the spectrum bandwidth coverage of the idler is up to 1652 nm together with 353-nm spectrum bandwidth for the signal. Next, we investigate the characteristics of the signal (1500 nm) and the idler (3287 nm) output power at different pumping level, as depicted in Fig.…”

“…[16][17][18][19][20] In 2018, we reported a 1030-nm laser pumped femtosecond OPO based on KTiOAsO 4 (KTA) crystal, producing signal pulses tunable across 1410 nm-1710 nm with the maximum output power of 2.32 W. However, the broad spectrum of the OPO requires high power laser pumping, which caused 3.11-W pump threshold. [21] MgO-doped periodically poled lithium niobate (MgO:PPLN) can excel other nonlinear crystal, owing to wide transparency ranges, high effective nonlinear coefficient (27.4 pm/V) and quasi-phase matching (QPM). [22][23][24][25] In 2011, a two-color femtosecond MgO:PPLN OPO was demonstrated, synchronously pumped by a 7.4-W mode-locked Yb:KGW laser, providing 1.5 W of the signal with durations of 425 fs due to long pump pulse durations and no intracavity dispersion compensation.…”