Sapphire, garnet and vanadate crystals are the most prominent optical materials, and vanadates play important roles in optics, especially in lasers and nonlinear optics. Neodymium-doped yttrium vanadate (Nd:YVO4) is representative and available commercially. Based on Nd:YVO4, several vanadate crystals are being developed with the goal of fulfilling the need for differential applications and improvement of certain operational aspects, such as with pulsed lasers or high-power continuous-wave lasers. In recent years, some important effects, including energy enhancement, bistability of output performance, self-Raman frequency shifting, etc., and some novel applications, such as quantum optics, pulsed lasers modulated by the two-dimensional crystals, etc., have been discovered with vanadates as gain materials. In this paper, the preparation, characterization and laser applications of vanadate laser crystals at the lasing wavelength of 1 micrometer, including YVO4, GdVO4, LuVO4, GdxY1–xVO4 and LuxGd1–xVO4 (0 < x < 1) doped with Nd3+ and ytterbium (Yb3+) are systematically reviewed by highlighting the most recent research progress. Their specific properties are presented, generation mechanisms of novel physical effects are discussed, new applications are given and possible future applications proposed by focusing on some potential strengths.

Advances in vanadate laser crystals at a lasing wavelength of 1 micrometer

Multi-wavelength continuous-wave laser operation of Yb:Ca3Gd2(BO3)4 disordered crystal

We report on the results from a comparative study on the continuous-wave laser performance of Yb:YGG, Yb:LuGG, and Yb:GGG gallium garnets grown by the optical floating zone technique, conducted under identical experimental conditions. 5−7 W of output powers were generated with the three garnet crystals in a compact linear resonator longitudinally pumped by a diode laser emitting at 970−974 nm. The optical-to-optical and slope efficiencies measured for Yb:YGG amounted to 68% and 80%, respectively, which proved to be much higher than the corresponding efficiencies for Yb:LuGG (49% and 60%) or Yb:GGG (52% and 64%).

Laser performance of ytterbium-doped gallium garnets: Yb:Re_3Ga_5O_12 (Re = Y, Gd, Lu)

We have studied the effect of optical bistability exhibited in the laser oscillation of Yb:GdVO4 crystal, revealing the complexities arising from the coexistence and switching of σ and π polarization states characteristic of this crystal. In terms of absorbed pump power, the range for bistable operation can be in excess of 1 W, while the output power generated at the up-threshold can reach as high as 0.71 W. The studies also show significant influence of the Yb concentration, the crystal thickness, the output coupling, and the resonator configuration on the bistable laser operation.

Study of the optical bistability in the laser oscillation of Yb:GdVO4 crystal

We report on the crystal growth, structural and spectroscopic investigation of a novel trigonal calcium vanadate crystal, Tm3+:Ca9La(VO4)7. Polarized absorption, stimulated-emission and gain cross-section spectra are determined for this material. The maximum σSE corresponding to the 3F4 → 3H6 transition amounts to 1.28 × 10−20 cm2 at 1854 nm for σ-polarization. The measured lifetime of the Tm3+ ions in the 3F4 state is 1.19 ms. The Judd-Ofelt analysis performed yielded intensity parameters of Ω2 = 4.682, Ω4 = 0.659 and Ω6 = 0.475 [10−20 cm2]. The polarized Raman spectra indicate a strong and broad band centered at 867 cm−1. Owing to the disordered nature of Ca9La(VO4)7, the Tm3+ ions exhibit a broad and smooth gain profile at ~2 μm. The spectroscopic properties of Tm3+:Ca9La(VO4)7 are very promising for broadly tunable and ultrashort pulse lasers near 2 µm.

http://nportal0.urv.cat:18080/fourrepo/rest/audit/digitalobjects/DS?objectId=PC%3A2576&datastreamId=DocumentPrincipal&label=PC%3A2576&mime=application/pdf&lang=en

Petrov

Papers

Solid-State Lasers - Comparative Study of High-Power Continuous-Wave Laser Performance of Yb-Doped Vanadate Crystals