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The polarized absorption, emission spectra, and the fluorescence decay curve of Er3+ ions in the anisotropic Ca3(BO3)2 crystal were investigated at room temperature. The experimental oscillator strengths for the transitions from the ground state to excited states were compared with the theoretical electric dipole oscillator strengths calculated from the Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] theory. The emission cross sections and gain cross sections of the π and σ spectra were determined for the 4H13/2→4H15/2 transition of special interest for laser application. [ABSTRACT FROM AUTHOR]

We have demonstrated two self-frequency conversions from the bifunctional laser and optical nonlinear GdAl3(BO3)4:Nd3+ crystal. For the first one, the laser operated in a dual-wavelength mode in the 4F3/2→4I11/2 (at 1062 nm) and 4F3/2→4I13/2 (at 1338 nm) channels, under a fixed wavelength pumping (at 747.7 nm) and with a fixed crystal orientation (28.5°). Then the self-sum frequency mixing 1/1062+1/1338→1/592 process occurred, leading to a weak yellow beam at 592 nm. In the second self-frequency conversion, the Nd3+:GdAl3(BO3)4 laser operated in a single wavelength mode at 1062 nm. Then the self-difference frequency mixing process 1/λP-1/1062=1/λI occurred at a 29.9° phase matching angle. The idler wavelength λI was tunable in the 2450–2600 nm range, due to the tunability of the λP pump wavelength. The highest yield was 0.12%. New Sellmeier formulas valid at least up to 2600 nm have been established. [ABSTRACT FROM AUTHOR]

The spectroscopic properties of GdAl3(BO3)4:Tm3+ single crystal for the Tm3+ transition near 1.9 μm are presented. The absorption cross section, the emission cross section, and the potential laser gain near 1.9 μm are investigated for both σ and π polarizations. The broad absorption band at about 797 nm and high value of the above cross section are promising features for obtaining a laser diode pumped Tm3+ laser. The maximum emission cross sections are 1.29×10-20 and 6.60×10-20 cm2 at 1.85 μm for the σ and π polarizations, respectively. The potential laser gain curves indicate that more than 200 nm tunability range is expected for this material. [ABSTRACT FROM AUTHOR]

We report a diode-end-pumped midinfrared multiwavelength Er:Pr:GGG laser, generating the output powers of 324 and 354 mW in CW and pulsed modes, respectively. The slope efficiencies of CW and pulsed modes are 15.18% and 16.06%, respectively. Compared with Er:GGG, the laser properties of Er:Pr:GGG are much better and the self-termination bottleneck is broken successfully. The transverse beam profile and spectra of Er:Pr:GGG laser are measured and the relationship between lasing wavelengths and operating temperature in the triwavelength emission state are also studied. The Er:Pr:GGG crystal is a potential midinfrared laser gain medium in medical and military application. [ABSTRACT FROM PUBLISHER]

As a laser host, Borates possess favorable chemical and physical characteristics as well as higher damnification threshold. Especially, Borates usually have higher nonlinear optical efficiency resulted from its B-O structure. When doped with active ions, Borates can serve as a self-frequency conversion multifunction laser medium. For example, rare-earth ions and Cr3+-doped RX3(B03)4, especially GdAl3(B03)4 and TmAl3(B03)4, are typical self-frequency conversion multifunction laser crystals. After wide surveys of known research on the growth, crystal structure, and properties including thermal, optical, and spectral characteristics and laser property, this chapter reviews the recent advances in the development of these crystals. Self-frequency conversion laser technology including the self-frequency doubling, self-difference-frequency mixing and self-sum-frequency mixing methods were dealt with. As a result, the laser outputs with high efficiency at various wavelengths ranged from UV to IR have been achieved. [ABSTRACT FROM AUTHOR]

From two positions of the concave output mirror of the laser cavity, diode-pumped ordinary or extraordinary polarization lasing of an Yb3+-doped GdAl3(BO3)4 nonlinear birefringent crystal is obtained. Translating the mirror at an intermediate position, simultaneous ordinary and extraordinary polarization lasing at 1046 (2.5 nm FWHM) and 1040 nm (2.2 nm FWHM), respectively, is obtained with up to 53% slope efficiency. Using a YAG:Cr4+ saturable absorber for passive Q-switching the cavity, ordinary and extraordinary pulses are obtained with an energy as high as 236 μJ and with about 30 ns duration. The two pulses of orthogonal polarizations can be separated by up to a few hundred ns, depending on the experimental conditions. The simultaneity of the pulses is observed but is difficult to maintain. A model constituted by two coupled equations reproduces reasonably well the experimental data. Repetition rates up to 3 kHz have been explored, corresponding to 4.65 W absorbed pump power. [ABSTRACT FROM AUTHOR]

This paper reports crystal growth and optical characteristics of dysprosium (Dy3+) and erbium (Er3+) doped mid-infrared laser crystal ternary-potassium-lead-chloride (KPb2Cl5). Two transparent crystals with good optical quality have been grown successfully by using the Bridgman technique,the largest crystal size reaches up to 10×60mm2. Measurements of X-ray diffraction(XRD) and absorption spectra were carried out. Based on Judd-Ofelt theory, the intensity parameters Ωt(t=2,4,6), the experimental and theoretical oscillator strengths have been obtained.The intensity parameters Ωt(t=2,4,6) of Er3+:KPb2Cl5 were calculated to be Ω2=5.10×10-20 cm2, Ω4=1.25×10-20 cm2, Ω6=0.83×10-20 cm2, and the values for Dy3+:KPb2Cl5 were calculated to be Ω2=6.26×10-20 cm2, Ω4=2.45×10-20 cm2, Ω6=0.04×10-20 cm2 respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Crystals of NaLa(WO4)2 : Ho3+ were grown by the Czochralski method. The spectroscopic properties have been investigated at room temperature. Intensity parameters, radiative lifetimes and branching ratios have been calculated in the framework of Judd-Ofelt theory. The luminescence spectra measured under 450 nm pumping are dominated by a strong green emission in the 550 nm region connected with the 5S2 + 5F4 - 5I8 transition. The stimulated emission cross-section for this transition was estimated. The luminescence decay curve of the 5S2 + 5F4 level was also measured at room temperature. [ABSTRACT FROM AUTHOR]

Ho3+-doped SrWO4crystal was grown by the Czochralski method. The polarized absorption and emission spectra together with the fluorescent decay curve were measured at room temperature. The intensity parameters, radiative lifetimes and branching ratios were calculated based on the Judd-Ofelt theory. The stimulated emission cross-sections of the potential laser transitions were determined using the reciprocity method. [ABSTRACT FROM AUTHOR]

A systematic investigation of room temperature absorption and emission spectra were presented for trivalent holmium in a crystal of NaY(MoO4)2. Oscillator strengths of the transitions to all levels up to 361?nm were calculated from the absorption spectra. Judd-Ofelt intensity parameters of Ho3+were used to calculate the radiative transition rates, branching ratios and radiative lifetimes. The emission cross-sections for the 5S2? 5I8and 5I7? 5I8transitions of special interest for laser application were determined. [ABSTRACT FROM AUTHOR]

Ca 3 Gd 2 (BO 3 ) 4 :Nd 3+ crystals of high optical quality with a size up to 20  ×  50  mm were grown by the Czochralski method. The absorption spectra of the crystal in three mutually perpendicular arbitrary directions were measured. Based on Judd–Ofelt and TPM methods, the intensity parameters Ω t ( t   =  2,  4,  6), the experimental and theoretical oscillator strengths, the radiative transition rates, radiative lifetime and fluorescent branching ratios of Nd 3+ from 4 F 3/2 to 4I J , were obtained. The fluorescence spectrum and decay curve under excitation at 808  nm were also measured. The stimulated emission cross-section and radiative quantum efficiency were also calculated. [ABSTRACT FROM AUTHOR]

We combine inside a single noncentrosymmetric laser crystal, GdAl[sub 3](BO[sub 3])[sub 4]:Nd[sup 3+], a stimulated emission and two second-order nonlinearities in cascade. The first one self-doubles the 1062.8 nm Nd[sup 3+] laser emission corresponding to the [sup 4]F[sub 3/2]→[sup 4]I[sub 11/2] channel, despite the fact that it is not phase-matched. The second one can be phase-matched or not and mixes the laser wave and its second harmonic (SH) in order to produce the third harmonic (TH) at 354.3 nm. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report ∼2.8 μm emission of Er3+-doped Lu3Ga5O12 crystal, as well as its laser performance. The continuous-wave (CW) and passively Q-switched lasers were both obtained for the first time at room temperature under 967 nm laser diode end pumping. A 384 mW of CW output power was obtained under the absorbed pump power of 3.28 W, corresponding to an optical-to-optical efficiency of 11.7%; the slope efficiency was 14.1%. A passively Q-switched laser with a maximum average output power of 274 mW was also achieved by utilizing a Bi2Te3/graphene heterostructure saturable absorber (SA). The shortest Q-switched pulse duration and the repetition rate were 340 ns and 135 kHz, respectively. [ABSTRACT FROM AUTHOR]

The polarized absorption spectra, polarized fluorescence spectra and fluorescence decay curve of Pr3+-doped NaLa(WO4)2 single crystals were measured at room temperature. The emission cross section has been presented and Judd-Ofelt theory has been applied to the analysis of the absorption spectra. The calculated radiative lifetime is compared with the experimental data for the 3P0 emitting level. The result indicates that the relaxation of the excited 3P0 level of praseodymium is governed by radiative transitions, which makes the 3P0 manifold of the Pr3+-doped NaLa(WO4)2 crystal promising as the upper laser level. [ABSTRACT FROM AUTHOR]