We present an infrared source operating at 1937 nm center wavelength capable of generating 1.35 mJ pulse energies with 1 kHz repetition rate and 2 GW peak power based on a diode-pumped Tm:YAP regenerative amplifier. The obtained pulses after 45 round trips have been compressed down to 360 fs. Using only a small portion (15 μJ) of the output of the system we managed to generate a white light continuum in a 3 mm YAG window that exhibits the viability of the system as a suitable candidate for a pumping source of a mid-infrared optical parametric amplifier.

A robust optical parametric amplifier (OPA) scheme is proposed in which we have experimentally achieved broadband bandwidth for a collinear OPA design that exhibits good beam quality and spatial distribution using a type-I $\beta$ barium borate crystal. The applied pump pulses are simultaneously spectrally broadened and temporally stretched in a multi-plate system before being used to amplify the temporally stretched white light. In this case, the phase matching can be obtained for a broad range of wavelengths, and we have managed to achieve bandwidths three times broader than a conventional narrowband pumped collinear OPA. With a bandwidth as broad as 400 nm centered at 1400 nm, as well as a broadband angular dispersion-free idler, the signal bandwidth supports transform-limited pulses as short as 7.5 fs which correspond to sub-two optical cycles for this center wavelength. Furthermore, the system is easily tunable over a 400 nm range of bandwidths starting from 1100 to 1500 nm. The proposed scheme provides a versatile near-infrared/middle-infrared source with a broad bandwidth and fine tuning capability which paves the way for ultrafast spectroscopy and strong field applications.

We propose a novel scheme that lengthens the plasma channel in filamentation with a multi-focal-length beam. Instead of one focal length introduced by a conventional convex lens, the multi-focal-length beam modulated by a spatial light modulator (SLM) produces a filament in an extended range with limited but strictly manipulated laser energy. The results show that the scheme is capable of doubling the filament length compared to a single-lens scheme with a 2-mJ input pulse. The filament location and length can be simply tuned by altering the spatial amplitude and phase or employing higher energies. Furthermore, the extended filament length leads to the generation of a broadened continuum ranging from visible (VIS) to infrared (IR) domain. This versatile scheme offers an efficient tool for the development of a variety of applications involving ultrafast nonlinear optics.

We present mid-infrared (MIR) supercontinuum generation in polarization-maintained ZBLAN fibers pumped by 2 µm femtosecond pulses from a Tm:YAP regenerative amplifier. A stable supercontinuum that spreads from 380 nm to 4 µm was generated by coupling only 0.5 µJ pulse energy into an elliptical core ZBLAN fiber. The supercontinuum was characterized using cross-correlation frequency-resolved optical gating (XFROG). The complex structure of the XFROG trace due to the pulse-to-pulse spectrum instability have been fixed by reducing the length of the applied fibers or improving the quality of the incident pulse spectrum.