Ultrashort pulse generation in the mid-IR

Abstract

Recent developments in laser sources operating in the mid-IR (3 -8 µm), have been motivated by the numerous possibilities for both fundamental and applied research. One example is the ability to unambiguously detect pollutants and carcinogens due to the much larger oscillator strengths of their absorption features in the mid-IR spectral region compared with the visible. Broadband sources are of particular interest for spectroscopic applications since they remove the need for arduous scanning or several lasers and allow simultaneous use of multiple absorption features thus increasing the confidence level of detection. In addition, sources capable of producing ultrashort and intense mid-IR radiation are gaining relevance in attoscience and strong-field physics due to wavelength scaling of re-collision based processes. In this paper we review the state-of-the-art in sources of coherent, pulsed mid-IR radiation. First we discuss semi-conductor based sources which are compact and turnkey, but typically do not yield short pulse duration. Mid-IR laser gain material based approaches will be discussed, either for direct broadband mid-IR lasers or as narrowband pump lasers for parametric amplification in nonlinear crystals. The main part will focus on mid-IR generation and amplification based on parametric frequency conversion, enabling highest mid-IR peak power pulses. Lastly we close with an overview of nonlinear post-compression techniques, for decreasing pulse duration to the sub-2-optical-cycle regime.

Passive Q-switching of ∼2.7 µm Er:Lu2O3ceramic laser with a semiconductor saturable absorber mirror

“…3,4) Approaches to realize ∼2.7 µm lasing include semiconductor technology, stimulated transition of doped ions, and nonlinear wavelength conversion. [5][6][7][8][9] In terms of good beam quality and simple structure, the approach of stimulated transition of doped ions is highly desired. Among known ∼2.7 µm ion-doped lasers, Er-doped lasers operating on the 4 I 11=2 → 4 I 13=2 transition are widely studied since their highpower pump sources are commercially available.…”

Kagome-fiber-based pulse compression of mid-infrared picosecond pulses from a Ho:YLF amplifier

“…Several important molecules offer resonances at the MIR wavelength, making them an optimum choice for spectroscopy [1]. Moreover, carrier-envelope phase (CEP)-stabilized few-cycle (sub-100 fs) laser pulses at long wavelengths are in high demand for complex experiments in attoscience and strong-field physics.…”

Optical Parametric Amplification Techniques for the Generation of High-Energy Few-Optical-Cycles IR Pulses for Strong Field Applications

“…When the DFG process generates a seed pulse in the terahertz (THz) domain, the process is called optical rectification, and it is widely benefiting from a new generation of non-oxide materials capable of providing optical transparency up to tens of µm, among which AgGaSe 2 (AGSe), ZnGeP 2 (ZGP), GaSe, GaP and ZnTe. A full list of NLO materials is provided in [24] for applications in the near-IR and in [25][26][27] for applications in the mid-IR.…”