Yu. P. Podmar’kov

Study of a 2-J pulsed Fe:ZnSe 4-μm laser

We report the results of a study of a pulsed Fe:ZnSe laser for temperatures ranging from 85 to 295 K. With a free-running Er:YAG laser, operating at 2.94 μm, as a pump source, a maximum output energy of 2.1 J at 85 K was produced at a wavelength of 4.1 μm. The optical-to-optical efficiency of the laser was 35% at maximum energy while the maximum absorbed energy slope efficiency was as high as 51%. By operating at 245 K (a temperature which can be easily reached using thermoelectric coolers) we achieved 1.3 J of output energy from an Fe:ZnSe laser, with a slope efficiency of 29% (23% optical-to-optical efficiency). The maximum output energy reached 42 mJ at room temperature (295 K). The temperature dependence of the lifetime of the 5T2 energy level of Fe2+ in ZnSe was studied in the 275–365 K temperature range. The activation energy for nonradiative relaxation was found to be 2235 cm−1.

3 J pulsed Fe:ZnS laser tunable from 3.44 to 4.19 μm

We report the laser properties of Fe:ZnS in the temperature range from 85 to 186 K. Under pumping by a pulsed free-running 2.94 μm Er:YAG laser, a maximum output energy of 3.25 J at 85 K was produced with 27% optical-to-optical efficiency. The output wavelength was observed to tune with temperatures from 3.60 μm at 85 K to 3.78 μm at 186 K. As the temperature was increased, the absorbed energy slope efficiency decreased from 42.4% at 85 K down to 2.5% at 183 K. With a CaF2 prism, the Fe:ZnS laser could be tuned from 3.44 to 4.19 μm at 85 K.

2.92 µm Cr2+:CdSe single crystal laser pumped by a repetitively pulsed Tm3+:Lu2O3 ceramics laser at 2.066 µm

A laser oscillator based on Cr2+:CdSe single crystal pumped by 2.066 µm radiation of a Tm3+:Lu2O3 ceramic laser was created and investigated. Repetitively pulsed oscillations at a wavelength of 2.92 µm with a bandwidth of 80 nm were demonstrated. The output power was up to 350 mW at 10 kHz repetition rate with a pulse duration of ~200 ns in the good-quality beam.

Mid-IR (4–5 µm) femtosecond multipass amplification of optical parametric seed pulse up to gigawatt level in Fe2+:ZnSe with optical pumping by a solid-state 3 µm laser

We demonstrate a first-of-its-kind efficient amplification of a broadband tunable (from 3.8 to 4.8 µm) mid-IR femtosecond seed pulse generated from a AgGaS2-based optical parametric amplifier pumped by a Cr:forsterite laser in a multi-pass Fe2+:ZnSe amplifier optically pumped by a solid-state nanosecond Cr:Yb:Ho:YSGG laser. A total gain of 2000 for an input seed energy of 40 nJ has been obtained. The magnitude of the output energy reaches 80 µJ at a pulse duration of 200 fs.

Toward sub-terrawatt mid-IR (4-5 micrometer) femtosecond hybrid laser system based on parametric seed pulse generation and amplification in Fe2+: ZnSe

For the first time, an experimentally measured seed pulse gain of about 2 cm−1 allows possibilities in the scaling power of such a femtosecond laser system in terawatts. The concept of a subterawatt power level hybrid femtosecond mid-IR (4–5 μm) laser system, based on a weak pulse from an optical parametric mid-IR seeder that is amplified in chalcogenide monocrystalline Fe2+:ZnSe, to gain medium has been proposed and designed. The method and approach for optimizing the choice of nonlinear medium, its length, and the required light intensity for the efficient non-linear self-compression of an ultrashort pulse has also been proposed and considered.

Continuous-wave broadly tunable diode laser array-pumped mid-infrared Cr2+:CdSe laser

We demonstrate the operation of a room-temperature, solid-state, broadly tunable Cr-doped CdSe single-crystal continuous-wave laser. Longitudinal pumping with a continuous-wave diode laser array at 1.94 μm produced a broadband output of 280 mW at 2.6 μm with an incident power slope efficiency of 12%. With an intracavity Brewster-cut CaF2 prism, we tuned the Cr2+:CdSe laser from 2.45 to 3.06 μm with a resolution of 10 nm and an output power up to 55 mW.

A compact Er:YLF laser with a passive Fe 2+ :ZnSe shutter

This paper describes an experimental study of the lasing of an Er:YLF laser at wavelengths 2.66, 2.71, and 2.81 µm under selective pumping by the radiation of laser diodes at wavelength 0.98 µm and passive Q-switching of the cavity by a shutter based on an Fe2+:ZnSe crystal. Single pulses are obtained with energy 3 mJ and width 30 ns at wavelength 2.81 µm.

High-power mid-IR (4–5 μm) femtosecond laser system with a broadband amplifier based on Fe2+:ZnSe

Concept of a solid-state femtosecond laser system with a multigigawatt power level in the 4–5 μm range has been proposed. The system contains an ultrashort pulse seeder, a two-stage chirped pulse amplifier based on a broadband Fe2+:ZnSe active element with optical pumping by a YSGG:Cr:Er laser, and an output stage that provides additional nonlinear optical compression of an amplified pulse to approximately 30 fs in a dielectric CaF2 medium with anomalous group velocity dispersion in this spectral range.

Efficient and compact pulse-periodic Cr2+:CdSe laser emitting in the wavelength regions of 2.8 and 3.3 µm

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).

Singlet oxygen in the low-temperature plasma of an electron-beam-sustained discharge

Results are presented from experimental and theoretical studies of the production of singlet delta oxygen in a pulsed electron-beam-sustained discharge ignited in a large (∼18-1) volume at a total gas mixture pressure of up to 210 Torr. The measured yield of singlet oxygen reaches 10.5%. It is found that varying the reduced electric field from ∼2 to ∼11 kV/(cm atm) slightly affects singlet oxygen production. It is shown experimentally that an increase in the gas mixture pressure or the specific input energy reduces the duration of singlet oxygen luminescence. The calculated time evolution of the singlet oxygen concentration is compared with experimental results.