Nikolai N. Il'ichev

A polarisation-bistable neodymium laser with a Cr4+:YAG passive switch under the weak resonant signal control

Abstract A polarisation-bistable device is proposed based on the phenomenon of dependence of polarisation state of a Nd:YAG laser passively Q-switched with a Cr 4+ :YAG crystal upon relative orientations of the switch and an intracavity polariser. The device is shown to operate as an all-optical transistor. One of the main parameters (polarisation) of the neodymium laser can be controlled by the relatively weak signal delivered from a CW laser or laser diode, the wavelength of which falls into the Cr 4+ :YAG resonant absorption band. The parameters ranges for both the powerful neodymium and weak controlling lasers are found, for which the most reliable and effective operation of the device is expected.

Efficiency of an Li–Nd–La phosphate glass laser at low pump energies. Free lasing

An investigation was made of the free-lasing regime in a high-concentration Li–Nd–La phosphate glass pumped in the energy range 1–15 J. A laser efficiency of 2.9% was obtained for a pump energy of 14.5 J. Estimates were made of the intracavity losses and the maximum attainable efficiency was determined. An investigation was made of the laser performance in the giant pulse regime and at pulse repetition frequencies of up to 25 Hz.

All-optical transistor based on polarization plane rotation in a neodymium laser passively Q-switched with a Cr4+:YAG crystal

A device is proposed which is based on the phenomenon of dependence of polarization state of a neodymium laser ((lambda) equals 1.06 micrometers ) passively Q-switched with a Cr4+:YAG crystal upon relative orientations of the switch and an intracavity partial polarizer. It is shown that such a device operates as an all-optical transistor. One of the main parameters (polarization) of the powerful neodymium laser can be controlled by the relatively weak signal delivered from a cw laser or laser diode, wavelength of which falls into the Cr4+:YAG crystal resonant absorption band (0.8 - 1.2 micrometers ).

Polarization characteristics of two-photon absorption in LiF : F2− crystal at wavelength 1.06 μm

Abstract The polarization characteristics of bleaching of LiF : F 2 − color centers due to two-photon absorption from the excited state under the influence of resonant radiation at wavelength 1.06 μm have been studied. The value of two-photon absorption cross-section has been measured.

Measuring nonlinear reflectance of laser radiation with a wavelength of 2940 nm from silica glass – water and silica glass – ethanol interfaces

We have measured the reflectance of an Er3+ : YAG laser pulse from silica glass – water and silica glass – ethanol interfaces at high (0.9 J cm-2) and low (5 mJ cm-2) energy densities of incident radiation. The nonlinearity of reflectance dynamics is found for high-power radiation during the laser pulse action.

Superluminescent room-temperature Fe{sup 2+}:ZnSe IR radiation source

The superluminescence of a Fe2+:ZnSe crystal was obtained in the region from 4.6 to 4.7 μm upon transverse pumping by high-power laser radiation at 2.94 μm. The superluminescence pulse energy was ~1 mJ upon pumping by a 15-mJ pulse. A ZnSe crystal was doped with Fe2+ ions by the diffusion method under the conditions of the thermodynamic equilibrium of phases.

Photovoltaic effect in water induced by a 2.92-{mu}m Cr{sup 3+}:Yb{sup 3+}:Ho{sup 3+}: YSGG laser

The appearance of the potential difference is observed on electrodes placed in a cell with water irradiated by a Q-switched 2.92-{mu}m Cr{sup 3+}:Yb{sup 3+}:Ho{sup 3+}:YSGG laser. (interaction of laser radiation with matter. laser plasma)

Experimental study and theoretical modeling of a self-Q-switched all-fiber Erbium laser

A self-Q-switched diode-pumped Erbium fiber laser is implemented in an all-fiber configuration. The laser operates in a stable regime of giant pulses in a broad range of pump powers and does not require additional intra-cavity elements except the active fiber and fiber Bragg gratings as output couplers. A modeling of the laser is developed, implying that the mechanism of self-Q-switching is the power-dependent thermo-induced lensing in Erbium active fiber that stems from the excited-state absorption at the laser wavelength.

Estimation of the saturation energy density in a 2.92-{mu}m Q-switched single-frequency Cr{sup 3+}:Yb{sup 3+}:Ho{sup 3+}:YSGG laser

An equation is derived for calculating the TEM{sub 00q}-mode energy density in a laser cavity using experimentally measured quantities (e.g., the reflectivity of the output mirror, the pump excess over the threshold, the output energy, and the TEM{sub 00q}-mode radius). The equation is used for estimating the saturation energy density in at 2.92-{mu}m Cr{sup 3+}:Yb{sup 3+}:Ho{sup 3+}:YSGG laser (lasers)

Study of the absorption saturation mechanism in a YAG:Cr4+ crystal by the Z-scan technique with taking into account of the nonlinear absorption anisotropy

Absorption saturation features and the correspondent nonlinear change of refractive index in a Cr4+:YAG crystal are studied applying the Z-scan technique in steady- state at wavelength 1.06 micrometers with taking into account of the crystal nonlinear absorption anisotropy.