A. K. Naumov

Ce3+-doped Colquiriite: A New Concept of All-solid-state Tunable Ultraviolet Laser

Abstract In this letter the first performance of tunable solid-state ultraviolet laser, based on 5d-4f transitions of Ce3+ ions in a colquiriite LiCaAlF6 single crystal, is reported. Our findings hold promise for devising a tunable u.v. all-solid-state laser pumped by the fourth harmonic radiation of any commercially available Nd laser.

Ce/sup 3+/-activated fluoride crystals as prospective active media for widely tunable ultraviolet ultrafast lasers with direct 10-ns pumping

New possibilities have been investigated for recently developed solid-state tunable ultraviolet (UV) laser materials such as Ce/sup 3+/ ion-activated LuLiF/sub 4/ (LLF) and LiCaAlF/sub 6/ (LiCAF). With their broad-gain width, demonstrated reliability, and high efficiency, they are attractive for ultrashort pulse generation and amplification. To prove that, we have demonstrated UV picosecond-pulse amplification using Ce:LLF. For such new laser materials, we proposed a passive self-injection seeding scheme for the direct generation of short-pulse trains, which does not require CW operation capability or an external short-pulse seeding laser, Using this simple scheme, a UV sub-nanosecond pulse train is directly and passively generated from Ce:LLF pumped by a standard 10-ns KrF excimer laser, and Ce:LiCAF pumped by the fourth harmonic of a conventional 10-ns Q-switched Nd:YAG laser. >

Potentiality of Pr3+- and Pr3++Ce3+-doped crystals for tunable UV upconversion lasers

Abstract Gain experiments based on the interconfigurational 4f5d to 4f 2 optical transitions in praseodymium-doped fluoride crystals were achieved. The measurements were performed under upconversion pumping of the 4f5d excited configuration via the 3 P J , 1 I 6 intermediate levels of the 4f 2 configuration, using a pump-probe set-up with three synchronized Q-switched nanosecond pulsed lasers. In spite of this two-step excitation, optical losses, due excited state absorption (4f5d→conduction band transition) leading to Pr 3+ ion photoionisation and color center formation, were too high to observe any amplification. However, these losses were found definitely weaker in fluoride crystals (Pr:LiYF 4 , Pr:LiLuF 4 ) than in oxides (Pr:YAlO 3 ) and, probing the 5d→4f emission of Ce 3+ under two-step excitation pumping of the Pr 3+ 4f5d states in co-doped Pr,Ce:LiLuF 4 crystals, no losses were detected at all.

Spectral-kinetic and lasing characteristics of new Nd3+-activated laser hosts of the KF-YF3 system

Abstract The results of the investigation of two new laser hosts are reported. Stimulated emission from Nd3+ ions has been observed for the first time in the two ordered fluoride crystals of the KF-YF3 system: KYF4 (FYK) and K2YF5 (PYFK). The major luminescent and lasing characteristics of the crystals are presented. The stimulated emission spectrum features and application prospects of the new laser hosts are discussed.

Ce 3+ :LuLiF 4 as a broadband ultravioletamplification medium

Ce(3+):LuLiF(4) is shown to have a broad gain spectrum, which is attractive for short-pulse applications. A large small-signal gain over 6 dB/cm and a sufficiently large saturation fluence of 50 mJ/cm(2) were observed for 10-ns probe pulses under KrF excimer laser pumping. In a confocal four-pass configuration, 17-dB amplification was demonstrated for 325-nm picosecond pulses, and 20-dB gain was demonstrated for cw laser light.

ULTRAVIOLET SHORT PULSES FROM AN ALL-SOLID-STATE CE:LICAF MASTER-OSCILLATOR-POWER-AMPLIFIER SYSTEM

We have developed an all-solid-state master-oscillator-power-amplifier system employing Ce:LiCAF, a new degradation-free tunable ultraviolet laser medium pumped by the fourth harmonic of conventional 10-ns Q -switched Nd:YAG lasers. The low- Q , short-cavity Ce:LiCAF master oscillator produced a satellite-free 1-ns pulse under appropriate pumping-fluence control. 18% energy extraction with sufficient gain was achieved in a single-stage, confocal, double-pass amplifier. As a result, 289-nm, 1-ns, 14-mJ pulses were efficiently obtained from this simple laser system.

Ce{sup {bold 3}+}:LuLiF{sub 4} as a broadband ultraviolet amplification medium

Ce(3+):LuLiF(4) is shown to have a broad gain spectrum, which is attractive for short-pulse applications. A large small-signal gain over 6 dB/cm and a sufficiently large saturation fluence of 50 mJ/cm(2) were observed for 10-ns probe pulses under KrF excimer laser pumping. In a confocal four-pass configuration, 17-dB amplification was demonstrated for 325-nm picosecond pulses, and 20-dB gain was demonstrated for cw laser light.

VUV and UV fluorescence and absorption studies of Pr(3+)-doped LiLuF(4) single crystals.

The laser-induced fluorescence spectrum of LiLuF(4):Pr(3+) single crystals, pumped by an F(2) pulsed-discharge molecular laser at 157 nm, was obtained in the VUV and UV regions of the spectrum at room temperature. A number of new fluorescence peaks were observed for the first time to our knowledge. They were assigned to the dipole-allowed transitions 4f5d ? 4f(2) of Pr(3+) ion. In addition, the absorption spectrum of the crystal samples was recorded. The positions of the bands with the 4f5d configuration were found to be 46 412, 53 267, and 63 397 cm(-1) from the ground state, (3)H(4), of the Pr(3+) ion. The edge (onset) of the 4f5d bands was at 45 100 cm(-1).

On the 4f25d→4f3 interconfigurational transitions of Nd3+ ions in K2YF5 and LiYF4 crystal hosts

Abstract The Laser Induced Fluorescence (LIF) spectrum of K 2 YF 5 :Nd 3+ (PFYK:Nd) and LiYF 4 :Nd 3+ (YLF:Nd) single crystals, pumped by the fluorine F 2 pulsed discharge molecular laser at 157.6 nm, was obtained in the Vacuum Ultraviolet (VUV) region of the spectrum. The fluorescence peaks were assigned to the 4f 2 5d→4f 3 dipole allowed transitions of the Nd 3+ ion. The 180 nm band of the LIF spectrum from the crystals indicates that the 4f 2 5d→4f 3 dipole transitions originate from the low Stark components of the 4 K 11/2 level of the 4f 2 5d configuration. The absorption spectrum of the crystal samples in the VUV was obtained as well and spectroscopic assignment of the levels of the 4f 2 5d configuration was made. The electric crystal field splits all the levels of single and mixed configuration. The energy of the Stark components of the 4f 2 5d configuration in YLF:Nd was shifted by few hundred cm −1 relative to that of PFYK:Nd. We observed eleven and nine dipole transitions, between the 4 I 9/2 ground level of the 4f 3 configuration and the Stark components of the levels of the 4f 2 5d configuration of the Nd 3+ ion, in YLF and PFYK crystal hosts, respectively.

Vacuum-ultraviolet interconfigurational 4f 3 → 4f 2 5d absorption and emission studies of the Nd 3+ ion in KYF, YF, and YLF crystal hosts

The laser-induced vacuum-ultraviolet fluorescence spectra of KY3F10:Nd3+ (KYF:Nd) and YF3:Nd3+ (YF:Nd) single crystals pumped by a pulsed-discharge molecular F2 laser at 157 nm were obtained. A number of new fluorescence peaks were observed and were assigned to the 4f25d → 4f3 dipole-allowed transitions of the Nd3+ ion. The absorption spectra of LiYF4:Nd3+ (YLF:Nd), KYF:Nd, and YF:Nd crystal samples in the vacuum-ultraviolet spectral regions were also obtained. Finally, the splitting of the states of the 4f25d configuration of the Nd3+ ion, which is due to the crystal field, was observed in all the crystal samples.