Active Media For Solid-state Lasers Research Articles

Irradiation effects and photostability of aerosil-filled polyurethane as a matrix for laser solid-state elements

Photooxidation processes during irradiation of the aerosil-filled polyurethane films, based on oligooxypropylene glycol, toluene diisocyanate and trimethylolpropane, for a use as the active media of solid-state lasers were investigated by means of the IR-spectroscopy and dynamic mechanical analysis (DMA) methods, depending on the inorganic dopant concentration (5 and 7 wt%). The IR-spectroscopic experiments showed that the introduction of aerosil slowed down these processes. Data from dynamic mechanical studies indicated that irradiation of aerosil-filled polyurethane matrices caused an increase in its structural heterogeneity and a drop of the elastic modulus. During irradiation of the polyurethane material with 7 wt% of aerosil, a partial destruction of the nanofiller spatial network was possible due to dispersion of the irradiation energy by the nanoparticles. The obtained results demonstrated a positive effect of the aerosil nanofiller on the polyurethane material stability under irradiation with an ultra-high pressure mercury lamp.

High emission cross-section Er3+-doped fluorophosphate glasses for active device application

The fluorophosphate (FP) glasses modified with different concentrations of Mg(PO3)2 and ErF3, were synthesized by simple melt-quenching technique. The effect of Mg(PO3)2 addition on structural and spectroscopic properties of the Er3+-doped FP glasses were explored. The glass stability factor was determined from thermal analysis that showed that the prepared glasses possessed greater stability above >100 °C. The Raman analysis was carried out in order to know the vibrational groups in the fabricated glasses. In order to study the local structure and covalency between Er3+ ions and ligand environment, the Judd-Ofelt parameters were derived by Judd-Ofelt theory from the absorption spectra of Er3+-doped FP glasses. The emission spectra showed an intense and broadband at 1532 nm originating from 4I13/2→4I15/2 transition of Er3+ ion upon 980 nm diode laser excitation. The larger emission cross-section of 2.15 × 10−20 cm2 and an extensive lifetime of 12.50 ms, respectively, were noticed for 3 mol% ErF3 and 40 mol% Mg(PO3)2 based FP glass. Considering those results, studied Er3+-doped FP glasses have a feasibility to be used as active media for solid-state lasers and optical amplifiers at 1532 nm.

Synthesis and investigation of highly transparent ceramics

A short review of research works carried out in the Institute of Electrophysics UrB RAS on the development of synthesis technology for laser ceramics and the analysis of their characteristics is presented. These ceramics are widely used as active media of solid-state lasers, transparent armor, envelopes of high intensity discharge lamps, heat-resistant and mechanically strong windows etc.

Upconversion luminescence dynamics of Er-doped fluoride crystals for optical converters

Erbium (Er)-doped fluoride crystals (YLF, BYF, CaF 2, etc.) are well-known as active media for solid-state lasers emitting in IR and VIS spectral domains, and as materials for efficient near-IR to VIS upconversion. In this paper, we report on the study of conversion of IR light from an ∼1.5 μm spectral region to an ∼1 μm spectral domain in low-phonon RE-doped fluoride crystals CaF 2 (RE=Er 3+ Yb 3+). Energy transfer processes taking place at selective pulsed and CW laser excitation are investigated experimentally. It is shown that in the CaF 2:RE crystals efficient conversion of IR radiation from the ∼1.5 μm region to the ∼1 μm region occurs, and these crystals are perspective for using in spectral converters for enhancing solar cell efficiency.

Growth and spectroscopic investigations of Yb3+-doped NaGd(MoO4)2 and NaLa(MoO4)2—new promising laser crystals

Abstract The absorption and fluorescence spectra, as well as fluorescence decay kinetics of Yb3+ ion in disordered scheelite-like double molybdates Yb:NaGd(MoO4)2 and Yb:NaLa(MoO4)2, grown by Czochralski, have been investigated. The absorption and fluorescence cross-sections of the transitions 2F7/2 ↔ 2F5/2 of Yb3+ ion in these crystals have been determined, gain spectra of laser medium have been calculated. Prospects of the application of investigated crystals as active media of solid-state lasers are discussed.

Yb-and Er-Doped single crystals of double tungstates NaGd(WO4)2, NaLa(WO4)2, and NaBi(WO4)2 as active media for lasers operating in the 1.0 and 1.5 µm ranges

Ytterbium-and erbium-doped single crystals of scheelite-like double tungstates NaGd(WO4)2, NaLa(WO4)2, and NaBi(WO4)2 and scheelite CaWO4 have been grown by the Czochralski method. The dopant concentrations in crystals are measured, and the coefficients of dopant distribution are determined to range from 0.45 to 3. The lifetimes of the Er3+ states 4 I 11/2 and 4 I 13/2 and the Yb3+ state 2F5/2 are measured, and the absorption and luminescence spectra of the crystals are studied in the vicinity of 1.0 and 1.5 µm. The data obtained are compared with the corresponding characteristics of other crystals. The possible use of the crystals studied as active media of solid-state lasers operating in the range 1.0 and 1.5 µm is discussed.

Crystals of Cr3+:Yb3+:Ln3+:YSGG as active media of solid-state lasers

An investigation was made of the active media of solid-state lasers based on Cr3+:Yb3+:Ln3+:YSGG crystals, where Ln3+ is Ho3+, Tm3+, or Er3+. The spectroscopic and lasing characteristics of these materials were determined.

Four-wave interaction due to a thermal nonlinearity in active media of solid-state lasers

A calculation is reported of the reflection coefficients for degenerate four-wave mixing in thermal gratings that form in the active media of solid-state lasers. It is shown that these reflection coefficients may be close to the reflection coefficients of amplitude gratings in the active media of ruby crystal and neodymium glass lasers.

Experimental manifestations of the smoothing out of thermooptic inhomogeneities in active media of solid-state lasers

Smoothing out of thermooptic inhomogeneities was observed experimentally in optically dense active media. Suppression of a thermooptic lens and an increase in the damage threshold to the active element were observed: these were attributed to the thermal effects of optical pumping, which increased on increase in the optical density of the active medium. The experimental results were in conflict with the traditional views and were explained by the concept of optically dense active media. The smoothing out effect made it possible to explain quite well the experimental observations.

Optically dense active media for solid-state lasers

The author has examined the potential of optically dense active media in solid-state lasers using, as an example, YSGG:Cr/sup 3+/,Nd/sup 3+/ active elements with a chromium concentration=1*10/sup 20/ cm/sup -3/, and a neodymium concentration=3*10/sup 20/ cm/sup -3/. One element had a square cross section (dimensions were 0.5*0.5*8 cm/sup 3/) and the other was cylindrical (0.4-cm-diameter, 7-cm-long). The optical density and geometrical size were chosen so that the limiting pump regime would be encountered at a relatively low average power. The solid-state laser pump cavity was cylindrical. This made it possible to compare the square (zig-zag) and cylindrical active elements under identical conditions. The results are presented. An effect, called the static STON-effect (smoothing of thermo-optical inhomogeneities), is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Rare-earth scandium chromium garnets as active media for solid-state lasers

Analysis has shown that the presence of Cr/sup 3+/ ions in rare-earth scandium garnets (RESG) crystals enhances the efficiency of laser ion transitions in these crystals. Results are reported of spectral-luminescent and laser investigations of the most efficient laser media presently achieved with these crystals.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Energy transfer in solids, new active media for solid-state lasers

Energy transfer in solids, new active media for solid-state lasers

Perenos energii v tverdykh telakh, novye aktivnye sredy tverdotel'nykh lazerov

Perenos energii v tverdykh telakh, novye aktivnye sredy tverdotel'nykh lazerov

New possibilities for Cr3+ions as activators of the active media of solid-state lasers

An analysis is made of the relationship between the excited-state lifetime of chromium and the ratio of the luminescence intensities in the 4T2–4A2 and 2E–4A2 channels, on one hand, and the Cr3+→acceptor energy transfer efficiency, on the other. A method is proposed for determination of the energy gap ΔE between the 2E and 4T2 levels of Cr3+ from the temperature dependence of the Cr3+→acceptor nonradiative transfer efficiency. Two independent methods were used to determine ΔE for gadolinium gallium garnet (GGG) crystals doped with chromium and with chromium and neodymium. The probabilities of Cr3+ intracenter relaxation and typical parameters of the Cr3+–Nd3+ energy transfer process were also determined. It was found that the values ΔE in gadolinium scandium gallium (GdScGaG) and lanthanum lutetium gallium garnet crystals are comparable with the values of kT at liquid helium temperature. It is shown that the high efficiency of the Cr3+→Nd3+ nonradiative transfer in GGG and GdScGaG crystals doped with chromium and neodymium at room temperature is due to the relatively low value of ΔE. It is noted that there are many crystals having the garnet structure and low values of ΔE that are potentially suitable for developing lasers utilizing the 4T2–4A2 electronic-vibrational transition in Cr3+ and having an emission frequency continuously tunable over a wide spectral range.