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We present directly oscillator-driven self-compression inside an all-bulk Herriott-type multi-pass cell in the near-infrared spectral range. By utilizing precise dispersion management of the multi-pass cell mirrors, we achieve pulse compression from 300 fs down to 31 fs at 11 µJ pulse energy and 119 W average power with a total efficiency exceeding 85%. This corresponds to an increase in peak power by more than a factor of three and a temporal compression by almost a factor of ten in a single broadening stage without necessitating subsequent dispersive optics for temporal compression. The concept is scalable towards millijoule pulse energies and can be implemented in visible, near-infrared and infrared spectral ranges. Importantly, it paves a way towards exploiting Raman soliton self-frequency shifting, supercontinuum generation and other highly nonlinear effects at unprecedented high peak power and pulse energy levels.

In this paper, the carrier‐envelope‐offset (CEO) frequency stabilization of a Kerr‐lens mode‐locked femtosecond oscillator with average power 105 W is presented. Intra‐cavity Kerr lensing is realized in a quartz crystal that simultaneously serves as an acousto‐optic loss modulator. This novel method results in a CEO frequency stable laser with high average power and a residual in‐loop phase noise below 90 mrad. Furthermore, an all‐solid‐state bulk broadening stage is presented. The compressed, CEO frequency‐stabilized output has a peak power exceeding 67 MW at a pulse duration of 40 fs and a repetition rate of 15.6 MHz. The intra‐cavity peak power of the CEO frequency‐stabilized oscillator is around 200 MW. These results pave the way toward compact, transportable all‐solid‐state drivers with high repetition rates for deep UV and XUV frequency combs and other nonlinear processes.

Received XX Month XXXX; revised XX Month, XXXX; accepted XX Month XXXX; posted XX Month XXXX (Doc. ID XXXXX); published XX Month XXXX Lasers based on Cr 2+ -doped II-VI material, often known as the Ti:Sapphire of the mid-infrared, can directly provide few-cycle pulses with super-octave-spanning spectra, and serve as efficient drivers for generating broadband midinfrared radiation. It is expected that the wider adoption of this technology benefits from more compact and costeffective embodiments. Here, we report the first directly diode-pumped, Kerr-lens mode-locked Cr 2+ -doped II-VI oscillator pumped by a single InP diode, providing average powers of over 500 mW and pulse durations of 45 fsshorter than six optical cycles at 2.4 µm. These correspond to a sixty-fold increase in peak power compared to the previous diode-pumped record, and are at similar levels with respect to more mature fiber-pumped oscillators. The diode-pumped femtosecond oscillator presented here constitutes a key step towards a more accessible alternative to synchrotron-like infrared radiation, and is expected to accelerate research in laser spectroscopy and ultrafast infrared optics.

We demonstrate an efficient hybrid-scheme for nonlinear pulse compression of high-power thin-disk oscillator pulses to the sub-10 fs regime. The output of a home-built, 16 MHz, 84 W, 220 fs Yb:YAG thin-disk oscillator at 1030 nm is first compressed to 17 fs in two nonlinear multipass cells. In a third stage, based on multiple thin sapphire plates, further compression to 8.5 fs with 55 W output power and an overall optical efficiency of 65% is achieved. Ultrabroadband mid-infrared pulses covering the spectral range 2.4- 8 µ m were generated from these compressed pulses by intra-pulse difference frequency generation.