Discharge formation in a copper vapor laser: optimal pumping conditions

The electrophysical process in the discharge circuit of a copper vapor laser (CVL) is investigated. It is shown that the pumping of the active medium of a CVL in gas-discharge tubes (GDT) with electrodes located in cold buffer zones is carried out in two stages. At the first (preparatory) stage, the capacitive components of the laser discharge circuit are charged from the storage capacitor, and at the second stage, the active medium is directly pumped. The transition from the preparatory stage to the pumping stage is carried out as a result of a breakdown. It is shown that breakdown is a transient process of discharge development from a glowing to a non-thermal arc discharge and is characterized by a sharp change in the cathode potential drop across the GDT. The inductance of the discharge circuit is a factor that determines the efficiency of pumping the active medium since the release of the energy stored in the inductance at the preparatory stage provides heating of the cathode spot and determines the conditions for the occurrence of thermal emission of electrons from the GDT cathode

Optimal pumping parameters of a copper vapor laser under breakdown conditions

The active medium of pulsed-periodic copper vapor lasers (CVL) is characterized by a high prepulse electron concentration ne0 1013 cm–3. Therefore, it was assumed that the development of the discharge under these conditions is carried out without the breakdown stage. However, as studies have shown, the development of a discharge in gas discharge tubes (GDT) with electrodes located in cold buffer zones (CBZ) is carried out with a breakdown stage

The efficiency of the pumping of the lasers based on self-terminating atomic transitions operating in the energy input cut-off mode

The analysis of the electro-physical processes in the discharge circuit of the lasers based on the self-terminating transitions of metal atoms (LSTM) and the electrodes placed in the cold buffer zones of the gas discharge tube (GDT) is occurred. That design of the GDT can provide the efficient lasing at the reduction of the current flowing through the switch to zero after the charging of the capacitive components of the circuit from the storage capacitor. Under the circumstances the pumping of the active medium is determined by the energy input from the peaking capacitor and, consequently, the efficiency of the pumping can be increased by an order of magnitude, if (using a managed switch) the energy input into the active medium from the storage capacitor is “cut-off” after charging the capacitive components of the circuit. It was shown that the efficiency values of ∼ 9-11 % and of ∼ 5-6 % for the copper and gold vapor, lasers could be achieved

Optical AR coatings of the Mid-IR band for ZnGeP2 single crystals based on ZnS and oxide aluminum

In this work, the parameters of antireflection interference coatings based on alternating layers of ZnS/Al2O3 on the laser-induced damage threshold (LIDT) of ZGP crystals under the action of Ho:YAG laser radiation at a wavelength of 2.097 μm were determined. The coating deposition was carried out using the ion-beam sputtering method. The LIDT of the sample with a coating based on alternating layers ZnS and Al2O3 was equal to WEo = 3.45 J/cm2, and the LIDT of the uncoated sample was equal to WEo = 2.23 J/cm2. An increase in the optical breakdown threshold by ~55% was observed after the deposition of an AR coating based on ZnS and Al2O3 materials. An assumption was made about the absence of local fluctuations in the composition and mechanical stresses in the case of the coated sample, namely that this leads to good adhesion of the multilayer coating to the polished surface of the crystal, and as a result to an increase in the optical breakdown threshold as compared to the uncoated sample due to closure of the dangling chemical bonds and bulk defects emerging on the polished surface

Multispectral anti-reflection coatings based on YbF3/ZnS materials on ZnGeP2 substrate by the IBS method for Mid-IR laser applications

A multispectral anti-reflective coating of high radiation strength for laser applications in the IR spectrum for nonlinear ZnGeP2 crystals has been developed for the first time. The coating was constructed using YbF3/ZnS. The developed coating was obtained by a novel approach using ion-beam deposition of these materials on a ZnGeP2 substrate. It has a high LIDT of more than 2 J/cm2. Optimal layer deposition regimes were found for high film density and low absorption, and good adhesion of the coating to the substrate was achieved. At the same time, there was no dissociation of the double compound under high-energy ions

Digital holography methods for visualization and identification of ZnGeP2 bulk defects

The volumetric filamentous inclusions in ZnGeP2 were visualized by digital holography, their characteristic sizes were determined, and their location in the sample volume was determined. The chemical composition of filamentous bulk inclusions – Zn3P2 and Ge-was determined by X-ray diffraction analysis. The influence of the second-phase inclusions (Zn3P2 and Ge) on the quasi optical characteristics (refractive index and absorption coefficient) in the resonant absorption band (12–12.5 microns) is established. The presence of bulk inclusions in the ZnGeP2 single crystal leads to an increase in the reflection coefficient in the region of 12.5 microns. The dispersion dependences of the refractive index and the absorption coefficient of the studied ZnGeP2 samples at wavelengths of 300–1000 microns in the non fundamental absorption region were obtained. The obtained experimental results confirm the assumption of the determining role of free carriers in the formation of dielectric losses in the wavelength range of 100–1000 microns. The hypothesis that one of the main sources of free carriers in ZnGeP2 is the matrix medium / inclusion interface of the second phase is confirmed.В ст. ошибочно: A. S. Bolshako

Threshold of laser destruction of nonlinear GaSe and GaSe:in crystals when exposed to pulsed radiation at a wavelength of 2.1 microns

The aim of this work is to determine the optical breakdown threshold of a single crystal GaSe and GaSe:In when exposed to nanosecond radiation of the two micron range and determining the influence of the energy parameters of the testing radiation on the breakdown threshold. The Ho3+:YAG laser was used as the laser radiation source in this work. Pumping was carried out by a Thule fiber laser.В ст. ошибочно: E. V. Zhuravle

The effect of volume inclusions of the ZnGeP2 single-crystal on the dispersion of the refraction index and the absorption coefficient in mid-IR and terahertz ranges of wavelengths

Volume filamentary inclusions in ZnGeP2 have been visualized using the digital holography method. The chemical composition of the filamentous volume inclusions Zn3P2 and Ge have been determined using the method of X-ray diffraction analysis. It is shown that the presence of volume inclusions in the ZnGeP2 singlecrystal leads to an increase in the reflection coefficient in the region of 12.5 μm. The dispersion dependences of the refractive index and the absorption coefficient of the studied ZnGeP2 samples at wavelengths of 300–1000 μm in the region of non-fundamental absorption have been obtained. It has been shown that the presence of volume inclusions in a single-crystal leads to an increase in the refractive index in the entire THz range under study by the value of Δnmax = 0,0008. The difference between absorption coefficients for the studied samples varies from Δα = 0.1 cm 1 to Δα = 0.15 cm 1 depending on the wavelength

Errors in determining coordinates in the digital holography of particles

Based on the approach applied to diffraction-limited optical systems, the study evaluates the measurement errors of transverse and longitudinal coordinates of particle images reconstructed from digital holograms. The paper shows the experimental results of testing the above estimates

Influence of post-post processing technology and laser radiation parameters on the optical breakdown threshold of a ZnGeP2 single crystal

The aim of this work is to determine the influence of the parameters of post-growth technological operations and experimental conditions on the threshold of optical breakdown of the surface of ZGP crystals under the action of laser radiation at a wavelength of 2091 nm