520-µJ mid-infrared femtosecond laser at 2.8 µm by 1-kHz KTA optical parametric amplifier

350-2500 nm supercontinuum white laser enabled by synergic high-harmonic generation and self-phase modulation

“…3a. The pump laser, being at a horizontal polarization state (namely, extraordinary light state), is a mid-IR femtosecond laser based on a home-built optical parametric amplification device [23], with a tunable center-wavelength mid-IR band from 2.86 to 3.6 μm. In our experiment, the central wavelength of the mid-IR femtosecond laser is adjusted to 3.6 μm to match the CPPLN sample design, with a repetition rate of 1 kHz, a pulse duration of 120 fs, corresponding to a pulse full width at half maximum (FWHM) bandwidth of around 357 nm, a setting pulse energy 45 μJ and average power of 45 mW, corresponding to a peak power of 0.38 GW (Fig.…”

Multi-mJ Scaling of 5-Optical Cycle, 3 µm OPCPA

“…Although these characteristics are ideal for the research of processes with low cross sections, energies below the mJ-level are not optimal for driving low-efficiency processes, such as soft X-ray high harmonic generation and for efficient laser wakefield acceleration, making the scaling in energy of the mid-IR pulses a highly promising and rewarding challenge. Existing state-of-the-art OPCPA systems operating at 3 µm can broadly be grouped into two classes: (i) high repetition rate sources (≥100 kHz) that operate at the multi-µJ-level, with the main reference systems at ICFO (131 µJ, 97 fs, 160 kHz), ELI Alps (152 µJ, 38 fs, 100 kHz), MBI Berlin (30 µJ, 70 fs, 100 kHz), and CELIA (8 µJ, 85 fs, 100 kHz) [11][12][13][14], and (ii) a very limited group with sources that can operate close or at the mJ-level but at lower (10-10,000 Hz) repetition rates, with the main reference systems at RIKEN (21 mJ, 70 fs, 10 Hz), Shanghai (13.3 mJ, 111 fs, 10 Hz), Singapore (2.7 mJ, 50 fs, 10 kHz), JILA (0.85 mJ, 420 fs, 1 kHz), and CAS Beijing (0.52 mJ, 100 fs, 1 kHz) [15][16][17][18][19]. State-of-the-art, high repetition rate mid-IR sources usually rely on periodically-poled lithium niobate (PPLN) for the non-linear medium [11,12,18] while mJ-level systems use mainly bulk material crystals, such as lithium niobate (LiNbO 3 , LN) [15,16] and potassium titanyl arsenate (KTiOAsO 4 , KTA) [20,21] (although in the latter case the output is already closer to 4 µm), clearly evidencing the potential of these crystals in withstanding and operating at high optical intensity levels.…”

Generation of wavelength-tunable few-cycle pulses in the mid-infrared at repetition rates up to 10 kHz

“…The other beam was split into a weak beam (0.18 mJ) and strong beam (1.62 mJ) for the pump pulses in the first and second stages of the two-stage OPA, respectively. The use of this multi-stage OPA has several advantages over pulse generation via a single stage only [28,29]. The advantages include the ability to compensate an angular chirp [28] and the robustness of the CEP owing to the collinear geometry, which does not require the beam locking with interferometric precision for spatially separated pump and signal beams used in DFG.…”