Generation of 1  kHz, 23  mJ, 88  fs, 25  μm pulses from a Cr²⁺:ZnSe chirped pulse amplifier

Abstract

We demonstrate the generation of 2.3 mJ, 88 fs, 2.5 μm laser pulses at 1 kHz repetition rate from a three-stage chirped pulse amplifier employing Cr:ZnSe crystals as the active gain media. 5 μJ seed of the amplifier is obtained via intrapulse difference frequency generation in a bismuth triborate (BIBO) crystal from spectrally broadened Ti:Sapphire amplifier output. A multi-pass amplifier followed by two single-pass amplifiers pumped by Q-switched Ho:YAG lasers boost the pulse energy to 6.5 mJ, yielding 2.3 mJ, 88 fs pulses upon pulse compression. Our results show the highest peak power at 2.5 μm with 1 kHz repetition rate. Such a laser will be a powerful source for studying strong-field physics and extending high-harmonic generation towards the keV region.

Millijoule femtosecond pulses at 1937 nm from a diode-pumped ring cavity Tm:YAP regenerative amplifier

“…However, OPA in general has complicated design due to the requirements of the precise synchronization between the pump and seed pulses while a very high intensity pump pulse is required for triggering the parametric amplification. This fact attracts a lot of attentions to the development of solid-state lasers, directly generating high energy ultrashort pulses around 2 µm, such as Tm:YAP, Ho:YAG, Ho:YLF, or Cr:ZnSe [17][18][19][20][21][22]. Regenerative or multi-pass amplifiers based on these materials can scale up nJ pulses directly to mJ energy levels while each material has its own advantages and disadvantages.…”

“…Cr:ZnSe has a large emission cross section and broadband gain spectrum. Very recently, sub-100-fs and multi-millijoule pulse generation at 2.5 µm has been demonstrated [22]. However, since its lifetime is only ∼6 µs it is necessary to use a high energy nanosecond laser at around 2 µm, for example a thulium fiber laser pumped Q-switched Ho:YAG laser, as a pump source for such lasers.…”

Generation of few-cycle multi-millijoule 2.5 μm pulses from a single-stage Cr2+:ZnSe amplifier

“…Nevertheless, it is clear that the aberrations will be significantly worse than for the normal incidence case as the peak temperature difference is the same in either case, while the distribution is more symmetric for the normal incidence crystals. In comparison with stage one of reference 21 the beam size of the pump was increased by a factor ≈2.7, while the pulse energy was increased by less than a factor 2, meaning that the fluence is more than halved here, thus further Figure 2. Normalized seed (blue) and amplifier (red) spectra of the laser system.…”

“…The peak power, 90 GW, is the highest achieved at 2.5 μm. By purging the entire laser system of water vapor with a nitrogen atmosphere and deploying a mid-infrared DAZZLER we were able to halve the pulse duration, compared to our previous system 21 , and produce near transform-limited pulses of 44 fs corresponding to less than 6 optical cycles. Further self-compression to less than two cycles in either a solid medium with negative GVD materials 30 or through hollow-core fiber compression 9 in order to generate isolated attosecond X-rays in the SXR water window seems very feasible.…”

Carrier-to-envelope phase-stable, mid-infrared, ultrashort pulses from a hybrid parametric generator: Cr:ZnSe laser amplifier system

“…More importantly, a single pulse CEP stability measurement capability of the current setup allows for the first ever CEP jitter characterization of an output of a Cr:ZnSe laser amplifier. Other implementations of a combination of parametric and laser amplification in the MIR, reaching longer carrier wavelengths [26], as well as higher energies [27], have been reported. However, in these previous reports the CEP stability of the laser-amplified output was not shown.…”