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We report the graphene-based passive mode-locking in Fe:ZnSe. The laser delivers 415 mW average power output radiation at a wavelength of 4.4 μm being pumped by 7-W fiber Er:ZBLAN laser. A pulse duration of 732 fs retrieved from the first-order autocorrelation function. Besides, we observed pulsed nanosecond oscillation under continuous-wave pumping and strong amplitude modulation caused by Kerr self-focusing. A numerical simulation of the soliton propagation in a laser cavity using the nonlinear Schrodinger equation supports obtained results. Such simple and effective ultrafast mid-IR high-repetition-rate coherent sources are designed to become a valuable tool in various fields of photonics.

We demonstrate the laser performance of a Fe2+:CdTe single crystal pumped by a Q-switched Er:YAG laser at room temperature. The Fe:CdTe laser produced 2 mJ of output energy at a central wavelength of 5.55 µm with a slope efficiency of 16% with respect to absorbed pump energy. The tunability was demonstrated in the wavelength range from 5.1 to 6.3 µm.

Efficient gain-switched output at 3.12 μm was achieved from the Cr2+:CdSe laser pumped at 2.1 μm by the repetitively-pulsed Ho3+:YAG laser. Two lasing regimes were registered, with the output wavelength centered at 3.12 μm or 2.7 μm, depending on the concentration of Cr2+ ions, crystal temperature, and Q-factor of a resonator. A high beam quality was maintained up to 2.5 W of an output power. The maximum output power reached 5 W.

Laser oscillator based on Cr2+:CdSe single crystal pumped by radiation of Tm3+:Lu 2 O 3 -ceramic laser was created and investigated. Repetitively-pulsed oscillations at the wavelength of 2.92 μm with bandwidth of 80 nm were demonstrated. The output power was up to 3W at 15–30 kHz repetition rate with the pulse duration of ∼40–300 ns in the good-quality beam.

Energies of over 10 J and efficiencies of over 44% have been demonstrated in single-shot operation of liquid nitrogen cooled single-crystalline Fe:ZnSe laser at 4100-nm wavelength.

The mid-IR cw tunable solid state two-mode Cr 2+ :ZnSe laser with intracavity methane cryocell was developed. The laser was applied for sub-Doppler spectroscopy of (ν1+ν4) vibrational-rotational band of methane and observation of narrow resonances of saturated dispersion at λ = 2.36 μm. The new technique of low pressure methane gas cooling was used instead of liquid nitrogen "jacket" design applied in our previous work. Parameters of saturated dispersion resonances were estimated in 77-300 K temperature range. The experiments confirmed that laser with the new "dry cooled" methane cell has prospectives for reaching a short- term frequency stability at the level of 10 -15 - 10 -16 and can be used as a compact device.

The mid-IR cw tunable solid state Cr2+:ZnSe laser with spectral density of intrinsic frequency noise less than 30 mHz/Hz1/2 was created. The laser was applied for sub-Doppler spectroscopy of (ν 1 +ν 4 ) vibrational-rotational band of methane and narrow resonances of saturated dispersion at λ = 2.36 µm were demonstrated for the first time. Characteristics of resonances and low frequency noise of the laser pave the way to a short-term frequency stability at the level of 10−15 – 10−16.