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An extensive study of a novel room-temperature mid-infrared Ce3+-doped Ge20Sb10Ga5Se65 glass laser is reported. An influence of output-coupler transmission on laser efficiency and emission spectra is investigated. Pumped by a pulsed Fe:ZnSe laser at 4.1 µm, a maximum output energy of 35 mJ is demonstrated at 5.2 µm, with a laser threshold of about 60 mJ and a slope efficiency of 21%. The tuning range of a mid-infrared Ce:glass laser is reported for the first time: with an intracavity prism, the laser is continuously tunable in the spectral range of 4.5–5.6 µm. The internal losses are determined to be below 9% per roundtrip.

We report the investigation of a repetitively pulsed laser based on a Fe : ZnSe crystal, cooled to a temperature of 195 K by two thermoelectric modules with a maximum cooling power of 34 W. Two pulsed synchronised Er : YAG lasers, operating in the free-lasing regime, are used for pumping. It is shown that the average laser power in a series of short pulses may exceed 20 W. An average power of 3.1 W is attained in the stationary temperature regime. The lasing spectrum is centred at a wavelength of 4.38 μm, and the total divergence angle is 5 mrad.

We report on experimental observation of four phase-locked bound soliton formation in a SESAM mode-locked $$\hbox {Cr}^{2+}$$ :ZnSe laser with an output power of 20 mW, a temporal pulse-to-pulse separation of 18.2 ps and single pulse duration of 1.4 ps. We demonstrate that birefringence can be used as an efficient mechanism to achieve bound state generation in solid-state lasers as an alternative method to Kerr-lens and SESAM saturation by a pump power increase or a total net cavity dispersion variation. In this work, we consider two different setup configurations to demonstrate the birefringence influence on bound soliton formation. The suggested technique could be effectively used in the realization of mode-locked lasers based on solid-state active media operating in bound-state or multi-bound regimes.

We report on the development and applications of a broadband mid-infrared spectroscopic system for sensitive measurements of CO2 isotopes in human breath and atmosphere, CO in breath after cigarette smoking, and N2O in gas flows. © 2021 The Authors

We present our recent results obtained with single-crystal Fe:CdTe lasers. In particular, different pumping schemes and operation temperatures are investigated. Our high-quality Fe:CdTe single-crystal has been grown using the physical vaportransport technology with simultaneous Fe2+-ions doping. When pumped by 40-ns pulses from a Q-switched Er:YAG laser at 2.94 μm, the Fe:CdTe laser produces up to 2 mJ of output energy at room temperature (RT), with a slope efficiency of 16 %. A spectral tunability in the range of 5.1–6.3 μm is achieved. The lifetime of the upper laser level is measured to be 530 ns at RT. When using a 4.1-μm Fe:ZnSe laser (40-ns pulses) as a pump source instead of Er:YAG, the efficiency of the Fe:CdTe laser is increased to 30 % and we obtain an output energy of 5.8 mJ at RT. Furthermore, a record 2300-nm smooth and continuous wavelength tunability over 4.5–6.8 μm is achieved. With the latter system we demonstrate the first application of the Fe:CdTe laser to intracavity absorption spectroscopy. The experimental spectrum of atmospheric H2O shows good agreement with a calculated spectrum from the HITRAN database. The obtained sensitivity corresponds to an effective absorption path length Leff = 10 m, being limited only by the laser-pulse duration. However, by applying longer pump-pulses, the sensitivity can be enhanced by up to seven orders of magnitude, thus enabling extremely sensitive spectroscopic measurements. Furthermore, an energy up-scaling of the laser output is demonstrated at 77 K. The increased upper-state lifetime of 68 μs facilitates pumping by 250-μs pulses of a 4.1-μm Fe:ZnSe laser, and our Fe:CdTe laser produces a record-output of 0.35 J at 77K, with a slope efficiency of 44 %.

High-energy mid-infrared (MIR) tunable lasers are of great interest for a variety of scientific, industrial and medical applications. Currently, intensive research is being conducted on new iron-doped telluride crystals, aimed at developing laser materials for the spectral range of 5–7 μm. Here we present our recent results obtained with single-crystal Fe:CdTe lasers. In particular, laser operation upon different pumping schemes and operation temperatures are investigated. The developed laser systems are characterized regarding efficiency, output energy and wavelength tunability. Furthermore, first applications of a Fe:CdTe laser for absorption spectroscopy will be discussed.

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.

We report a laser operation from a Fe:CdTe single crystal, pumped by 40-ns pulses of a 4.12-µm Fe:ZnSe laser. The maximum output energy of 5.8 mJ was produced at 5.4 µm with 30% absorbed energy slope efficiency. A record 2300-nm-wide smooth and continuous wavelength tunability over 4.5-6.8 µm range was demonstrated, being the longest wavelength tuning achieved for Fe2+-doped chalcogenide lasers. We also discuss the features of the oscillation spectra.

In high purity C e 3 + -doped selenide glass pumped by a 4.08 µm Fe:ZnSe laser, 5.1–5.5 µm laser oscillations were observed. This is the first evidence of laser action corresponding to the 2 F 7 / 2 → 2 F 5 / 2 transition of C e 3 + ions.

High-energy laser operation of a F e 2 + -doped single-crystal CdTe is demonstrated at the temperature of 77 K. Pumped with 250 µs pulses of a 4.08 µm Fe:ZnSe laser, the Fe:CdTe laser produced a record output of 0.35 J, with a slope efficiency of 44%. A further up-scaling by employing high-energy pump sources is feasible, thus facilitating material-processing applications. The laser was tunable from 4.86 to 5.37 µm. In a nonselective cavity, the laser’s central wavelength was 5.03 µm at 77 K, and shifted to 5.23 µm at 215 K. At the later operation point, reachable using a Peltier element, the laser still produced 0.15 J of output energy with an efficiency of 22%.

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 the central wavelength of 5.55 µm with 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. The lifetime of the upper laser level was estimated to be of 530 ns at room temperature.

We report a laser operation from an AR-coated Fe:CdTe single crystal with wavelength tunability range over 4.5 – 6.8 µm under 40-ns pulses at 4.12-µm excitation by Fe:ZnSe laser. The maximum laser output energy of 5.8 mJ with a slope efficiency of 30 % was achieved.

We report the first-of-its-kind compact and robust coherent source operating in mid-IR based on Fe:ZnSe chalcogenide gain medium optically pumped by Er:ZBLAN fiber laser. In the research, we study the CW operation of cryogenically cooled laser based on Fe:ZnSe single crystals with different doping level grown from the vapor phase on a single-crystal seed by using the concurrent-doping technology. The maximal output power achieved is 2.1 W with 59% slope efficiency with respect to absorbed pump power, which is close to the Stokes shift limit. Measured Fe:ZnSe output spectra indicate a significant influence of re-absorption on generation wavelength. For high doping levels and output powers, spectrum shifts to the red wing, which makes possible continuous tuning from 4012 to 4198 nm. As well, tunability of the laser in a wide range of temperature is investigated.

One-dimensional gratings with a period of are formed on the surfaces of CdSe and ZnSe crystals ablated by two interfering radiation beams of a nanosecond excimer KrF laser. Investigated are the dependences of the shape and depth of gratings on the energy density under irradiation by a single pulse, and on the number of pulses at a given energy density. The maximum grating depth is estimated as of the period. By forming a one-dimensional grating with a period of and a depth of on the CdSe-crystal surface, this surface becomes antireflective at a wavelength of . The surface reflectivity is reduced by 88 %. A possibility of forming two-dimensional gratings having periods of 1 and is demonstrated.

New spectroscopic knowledge of the ν 1 + ν 4 R(2) E line of methane over the temperature range 77–300 K is reported. Theoretical calculations of the absorption coefficient and the amplitudes of saturated dispersion resonances at 4234 cm−1 were derived. The theoretical dependence on the temperature of the amplitudes of the saturated dispersion resonances was obtained. A novel setup based on a Cr 2 + : ZnSe laser was used for Doppler-free spectroscopy of methane. The amplitudes of the saturated dispersion resonances of the ν 1 + ν 4 R(2) E line of methane were measured experimentally at different temperatures. A comparison with theoretical dependence supports the reliability of the experiment. The obtained results are of immediate interest in applications demanding laser frequency stabilization.

We report the generation of the tunable phase-locked bound solitons in a SESAM mode-locked Cr2+:ZnSe laser. The bound solitons generation with the phase-locked pulses number of 4 and 8 were achieved with the pulse separation of 9.39 ps and 19.7 ps.

The first CW single-crystal Fe:ZnSe laser optically pumped by Er:ZBLAN fiber laser with an output power of 2.1 W is reported. Temperature-dependent spectral characteristics and tuning (3.8-5.1 μm) are investigated.

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.

Efficient chirped pulse amplification of broadband mid-IR (4-5 µm) femtosecond seed pulse (230 ps, 4µJ) generated in AgGaS 2 based OPA driven by Cr:forsterite laser in multi-pass Fe2+:ZnSe amplifier optically pumped by solid-state Q-switched Cr:Yb:Ho:YSGG laser (2.85 µm, 30mJ, 5Hz, 0.6 J/cm2) has been demonstrated. The hybrid system delivers 2.1 mJ at pulse duration of 230 ps. Straightforward compression to 150 fs pulse is achievable with 70% efficiency using diffraction grating pair with peak power of about 10.5 GW. Further grating based and non-linear compression in a bulk CaF 2 due to the SPM and anomalous GVD should provide the enhancement of peak power up to 35 GW. Possible routes to reach sub-TW and even TW power level in mid-IR are discussed.

Pulse-periodic lasing at wavelengths of 2.8 and 3.3 µm is obtained in the Cr2+:CdSe single-crystal laser. In the region of 2.8 µm, the pumping conversion is 28% (more than 50% of the absorbed energy). In the region of 3.3 µm, lasing is achieved at several tunable narrow lines appropriate for using in remote lidars. The pumping conversion in this spectral region is more than 17% (more than 30% of absorbed energy).

We report on more than 2 W continuous wave single mode Cr2+:CdSe laser generation. For the first time, luminescence lifetime dependence on temperature for Cr2+:CdSe single crystal in 236-391 K range was obtained.

The characteristics of a Fe:ZnSe laser pumped by a single-pulse free-running Er : YAG laser and a repetitively pulsed HF laser are presented. An output energy of 4.9 J is achieved in the case of liquid-nitrogen cooling of the Fe2+:ZnSe active laser element longitudinally pumped by an Er:YAG laser with a pulse duration of 1 ms and an energy up to 15 J. The laser efficiency with respect to the absorbed energy is 47%. The output pulse energy at room temperature is 53 mJ. The decrease in the output energy is explained by a strong temperature dependence of the upper laser level lifetime and by pulsed heating of the active element. The temperature dependence of the upper laser level lifetime is used to determine the pump parameters needed to achieve high pulse energies at room temperature. Stable repetitively-pulsed operation of the Fe2+:ZnSe laser at room temperature with an average power of 2.4 W and a maximum pulse energy of 14 mJ is achieved upon pumping by a 1-s train of 100-ns HF laser pulses with a repetition rate of 200 Hz.

We report the highest slope efficiency from a Cr2+:CdSe laser. The sample was multilayered dielectric coated with TaO 2 and SiO 2 to achieve this performance. The output beam was a diffraction limited TEM 00 gaussian mode.

We demonstrate an efficient amplification of the broadband tunable (from 3.8 μm up to 4.8 μm) mid-IR femtosecond (∼200 fs) seed pulse in optically pumped Fe2+:ZnSe amplifier [1]. The experimental setup is sketched in Fig. 1a. Seed radiation was generated in two-stage AGS-based optical parametric amplifier pumped by Cr:forsterite laser [2]. Mid-IR output radiation with energy up to 1 μJ was then directed into a multipass amplifier. Iron-doped ZnSe crystal was pumped by Q-switched Cr:Yb:Ho:YSGG laser with 40 ns pulse duration, total energy of 20 mJ, operating at 2.85 μm wavelength [3]. In order to prevent carbon dioxide absorption, the last OPA stage and multi-pass amplifier was placed in the chamber, where atmospheric air was substituted by noble gas. Prior to the main experiments, gain evolution measurements were carried out. They have shown that the lifetime of population inversion of Fe2+:ZnSe strongly depends on the temperature. It increases from 350 ns (at room temperature) up to 1 μs (at 7 degrees Celsius) paving the way for multi-pass amplification. As a result, femtosecond seed radiation with energy 0.7 μJ centered at 4.3 μm was amplified in six-pass Fe2+:ZnSe amplifier up to the energy 70 μJ (Fig. 1b), which corresponds to 0.5 GW peak power. Decreasing of the input energy down to 40 nJ did not prevent to decrease in output energy. Therefore the total gain was about 2000. Inset in fig. 1 (b) presents far-field beam profile of amplified pulses. Substitution of air by argon removes spectral distortions in the laser pulse caused by the absorption by atmospheric CO 2 molecules. It does not radically improve the amplification process in Fe2+:ZnSe but stabilizes the operating regime (Fig. 1c).

We report a room temperature (RT) operation of a Fe:CdTe laser pumped by a Q-switched 2.94 μm Er:Y3Al2(AlO4)3 laser. The Fe:CdTe laser produced 2 mJ of output energy at λ=5.55 μm with slope efficiency of 16% with respect to absorbed pump energy. With the use of an intracavity prism, the spectral tuning was demonstrated in the 5.1–6.3 μm range, being the longest wavelength tuning achieved for Fe2+:II–VI lasers. The lifetime of the upper laser level was measured to be 530 ns at RT.

We report on the study of quenching and thermal lensing based on simple effective lens approximation in a Cr2+:CdSe active medium, including detailed research on the medium’s luminescence lifetime dependence on temperature in the 236–391 K range. This work has allowed us to partially overcome the limitations associated with thermal effects in the medium and build a laser system that allowed power scalability to be realized for the Cr2+:CdSe laser. Longitudinal pumping using a continuous-wave Tm-doped fiber laser at 1.908 μm produced an output of 2.3 W at 2.65 μm with an absorbed pump power slope efficiency of 47.6%, which, to the best of our knowledge, is the highest output power achieved in Cr:CdSe continuous-wave lasers.

A Yb femtosecond laser was used to fabricate antireflective microstructures on CdSSe single crystal samples. We investigated several microstructure fabrication methods, including direct single pulse ablation using 200 fs pulses, ablation with in-depth focusing, ablation in the presence of additional spherical aberration and ablation with obstruction of peripheral rays. We performed a comprehensive analysis of the implemented antireflection microstructure fabrication methods. The performances of the antireflection microstructures were measured using an infrared Fourier spectrum analyzer and the best samples demonstrated $>99\%$>99% transmission in the 4.5–6 µm range and average transmission near $97\%$97% in range from 2.7 to 8 µm.

We report the efficient gain-switched high-repetition-rate Cr2+:CdSe single-crystal laser operating around 3 μm and pumped at 2.09 μm by a fiber-laser-pumped Ho3+:YAG laser. Average power of up to 6 W with the optical-to-optical efficiency of 67% at 2.65-2.85 μm was achieved in the Cr2+:CdSe laser with nanosecond pulses at 8 kHz repetition rate. Wavelength tunability from 2.5 μm to 3.15 μm was demonstrated using a set of cavity mirrors and an intracavity Lyot filter.

We report the demonstration of zinc selenide single crystal reflectivity reduction in a spectral range of 3.5 to 15 µm up to 3% by using femtosecond laser pulses for microstructure formation without any etching technique.

We demonstrated a continuous-wave laser using an anti-reflection coated Cr2+:CdSe crystal with transmission of 98 % at wavelength range from 2.0 to 2.7 μm and with relatively large laser damage threshold of 30 MW/cm2 for the first time. A maximum output power of 1 W at wavelength 2450 nm with an optical-optical efficiency of 48 % and a slope efficiency of 50 % was obtained when the incident pump power was 2.1 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.

An output power of 0.85 W with a differential efficiency with respect to absorbed pump power of 55.4% is achieved for a Cr2+:CdSe laser with a wavelength of 2.6 µm under optical pumping with a semiconductor disk laser with a wavelength of 1.98 µm.

We realized laser generation on a Fe2+:ZnTe crystal for first time. The crystal was pumped at room temperature by 40 ns pulses of an Er:YAG laser operating at a wavelength of 2.94 μm in the Q-switching mode. The output energy of the Fe2+:ZnTe laser was 0.18 mJ at a slope efficiency of 2.4% with respect to absorbed pumping energy. We achieved tuning of the Fe2+:ZnTe laser generation wavelength within the range of 4.35–5.45 μm using a prism-dispersion cavity.

Repetitive-pulse generation of the diode-pumped Er:YAG laser (λ =2 .94 μm) in the free mode and in the mode of cavity passive Q-switching was achieved using a Q-switch based on the Fe 2+ :ZnSe crystal. When using pump pulses 3 ms long, the pulse-average output power of the Er:YAG laser in the free generation mode was 0.5 W. In the passive Q-switching mode, giant pulses 180 ns long with an energy of 3 μJ were obtained. DOI: 10.3103/S1068335610060035

Seeded free growth method with physical transport was used for preparation of large-size II—VI single crystals uniformly doped by transition metals directly during the growth. The grown crystals possess small intrinsic losses. Based on these crystals new results on development of mid-IR lasers were achieved. With the CdSe:Cr crystal pumped at the room temperature (RT) by a continuous wave (CW) 1.908-μm thulium fiber laser, output laser power at 2.6 μm was increased up to 1.7 W. CW lasing from the ZnSe:Fe crystal was achieved using the 2.97-μm CW Cr 2+ :CdSe laser as a pump source. In this case the output power as high as 0.2 W was obtained at 4.1 μm and T=80 K. Broad spectral tuning of the Cr 2+ :CdSe (2.26-3.61 μm) and Fe 2+ :ZnSe (3.95-5.05 μm) lasers was achieved at RT in the pulsed operation. The RT laser action from CdS:Cr and CdSe:Fe was demonstrated for the first time. The output power of the CW Cr +2 :CdS laser was 0.81 W. The pulsed Fe 2+ :CdSe laser was tuned in the 4.6-5.9 μm spectral range.

The characteristics of an Fe:ZnSe laser thermoelectrically cooled to 220 K are described. Output energy of 7.5 J and optical-to-optical efficiency of 30% have been demonstrated in single-shot operation at 4.3 μm with a 2.94 μm Er:YAG pump laser. By using an intracavity prism, continuous tuning from 3.75 to 4.82 μm has been obtained at output energy up to 3.1 J.

We report the spectroscopic characteristics and laser properties of Cr2+:CdS. The emission lifetime of the exited state, 5E, of Cr2+ in CdS host was measured to be 0.93 µs at room temperature and 7.3 µs at liquid nitrogen temperature. The measured values of peak absorption and emission cross sections were found to be 1.4×10−18 and 1.1×10−18 cm2 respectively. Room-temperature pulsed-laser operation was obtained under pumping by the 1.94 µm output of a Tm:YAP laser. The output of the free-running Cr2+:CdS laser was centered at ∼2.6 µm, and an absorbed energy slope efficiency of 38.8% was demonstrated. The passive crystal losses were measured to be less than 0.049 cm−1 at the lasing wavelength. With an intracavity prism, the Cr2+:CdS laser was tuned from 2.18 to 3.32 µm.

A continuous-wave oscillation is obtained for the first time in a Fe2+:ZnSe laser. The laser wavelength was in the range from 4.04 to 4.08 μm. A liquid-nitrogen-cooled active element was pumped by a Cr2+:CdSe laser at 2.97 μm. The maximum output power of the laser was 160 mW with the 56% slope efficiency. The minimum absorbed pump power threshold was 18 mW. The intrinsic losses in the Fe2+:ZnSe crystal did not exceed 0.024 cm-1 during lasing.

The efficient lasing of a Cr2+:CdSe single crystal pumped by 1.94-μm, 300-μs pulses from a Tm:YAP laser was obtained. The Cr2+:CdSe laser with a nonselective resonator emitted up to 17 mJ at a wavelength of ~2.65 μm with the quantum slope efficiency of 63% with respect to the absorbed pump energy. The absorption coefficient of the Cr2+:CdSe crystal at the laser wavelength did not exceed 0.045 cm-1. By using a resonator with a dispersion prism, the laser wavelength was continuously tuned in the spectral range from 2.26 to 3.61 μm.

A Fe2+:ZnSe laser emitting in the spectral range between 3.77 and 5.05 μm is used for the first time for intracavity laser spectroscopy. The intracavity absorption spectra of methane in the 4.1-μm region are recorded at different instants of lasing (0–80 μs) and the dynamics of spectral holes during lasing is investigated. It is found that an intracavity absorption signal linearly increases with time during lasing in the time range from 0 to 80 μs, which provides the effective absorption length up to 24 km.

Spectroscopic properties and lasing of Fe:ZnSe and co-doped Fe:Cr:ZnSe crystals in the mid-infrared spectral range were studied at room and low temperatures. Using a free-running Er:YAG laser as a pump source, the output energy of the thermoelectrically cooled Fe:ZnSe laser was 142 mJ with 30% slope efficiency at T=220 K. Passive Q-switched oscillation of Er:YAG laser with Fe:ZnSe crystal was demonstrated and used as a pump source for a Fe:ZnSe laser system. Room-temperature (RT) gain-switched lasing of Fe:ZnSe was achieved in microchip and selective cavity configurations using Q-switched Er:YAG and Raman-shifted Nd:YAG lasers as pump sources. The microchip laser threshold of 100 mJ/cm2 was demonstrated using a Fe:ZnSe crystal without any reflection coatings. A slope efficiency of 13%, oscillation threshold of 1.3 mJ, and tunable oscillation of Fe:ZnSe laser systems over 3.95-5.05 mum spectral range were realized at RT

A modified vapour phase contact-free method to grow homogeneous single crystals of II-VI compounds doped by transition metals is presented. Single crystals of ZnSe:Cr, ZnSe:Fe, ZnSe:Co, ZnSe:Ni, CdSe:Cr, ZnTe:Cr, ZnS:Fe and ZnS:Mn with doping level up to 1019 cm–3 have been grown. Efficient lasing at about 2.5 and 4 µm with ZnSe:Cr and ZnSe:Fe crystals respectively has been achieved. Dependence of Fe2+:ZnSe laser characteristics on temperature is presented in more detail. A possibility of using Cr2+:ZnSe laser in intracavity laser spectroscopy is demonstrated. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The temperature dependence of the efficiency of a laser based on a Fe:ZnSe crystal grown from the vapour phase by the free-growth method is studied in the 85-255-K temperature range. As the temperature was increased, the slope efficiency of the laser with respect to absorbed energy decreased from 43% (at 85 K) down to 9% (at 255 K) and its emission spectrum shifted from 4.0 to 4.17 mu m. Lasing was obtained in a Fe2+:ZnSe crystal cooled with a thermoelectric module down to similar to 220 K. In this case, the slope efficiency of the laser with respect to absorbed energy was 30%. The output energy of the thermoelectrically cooled laser was 142 mJ for the slope efficiency with respect to the incident pump energy equal to 21%.

The growth dynamics of intracavity absorption is studied during recording line absorption spectra by the method of intracavity laser spectroscopy using a pulsed Cr2+:ZnSe laser tunable between 2.1 and 3.1 μm. In the lasing duration range from 0 to 235 μs, an intracavity absorption signal increases linearly with time, providing the effective absorption length of 70km.

The method of intracavity laser spectroscopy using a Co:MgF2 laser is applied to record the absorption spectra from the first excited a1Δg state of gaseous molecular oxygen at the a1Δg → b1Σg+ transition at 1.91 μm. The gas flow from a chemical singlet oxygen generator with a known concentration of singlet oxygen O2 (a1Δg) was supplied to the cavity of the Co:MgF2 laser. The absorption line intensities are measured for five spectral lines of the Q-branch of the 0–0 vibrational band for the a1Δg → b1Σg+ transition. The O2 (b1Σg+ → a1Δg) transition probability calculated from these data was (1.20 ± 0.25) × 10-3 s-1.

A Cr2+ : ZnSe laser emitting 100-μs pulses tunable in the 2–3-μm region is used for the first time for the highly sensitive detection of absorption spectra by the method of intracavity laser spectroscopy. The intracavity absorption spectra of the atmospheric air were recorded at different instants of lasing in the spectral region from 2.41 to 2.46 μm. An increase in the sensitivity of the laser emission spectrum to intracavity absorption was observed over the entire range of lasing durations studied.

The results of experimental and theoretical studies of operation regimes of a pulsed chemical D2–F2–CO2 UV initiated laser are presented. The influence of particular mixture components, the power of the UV radiation source, and the resonator's characteristics on the output radiation parameters are experimentally studied on the “Kaiman” setup. The results of theoretical simulation obtained using the proposed scheme correspond sufficiently to those obtained experimentally. A description is given of the pulsed D2–F2–CO2 UV initiated laser “Flash-1” that provides for radiation pulses of 18 J with a 2.6–3.5 μs duration in the 10-micron range. A detailed description is given of the precision diagnostics of dark reactions occurring during the mixture preparations and affecting the efficiency of energy extraction in the course of generation.

Saturated dispersion resonances of the methane E(2)-line ν 1 +ν 4 -band over the temperature range 77–300 K were observed with two-mode Cr2+:ZnSe laser with intracavity absorption cell. The resonances amplitudes were measured and compared with calculations.