V. I. Dashkevich

Quasi-continuous wave and continuous wave laser operation of Eu:KGd(WO4)2 crystal on a 5D0 → 7F4 transition

We report on the first demonstration of quasi-continuous wave (quasi-CW) and real CW room-temperature lasing on the 5D0 → 7F4 transition of Eu3+-doped material using a 25 at.%Eu3+ : KGd(WO4)2 crystal pumped into the 7F1 → 5D1 transition by a diode-end-pumped Nd3+ : KGd(WO4)2/KTP green laser at 533.6 nm. The maximum CW output power of this laser at 702.3 nm is 5.3 mW with 1.4% green-to-red conversion efficiency. In quasi-CW operation mode with a 10% duty cycle, the peak power of ms long pulses reaches ~54 mW, which corresponds to the optical conversion efficiency of 3.5%.

Red Eu,Yb:KY(WO4)2 laser at ~702 nm

In this letter, laser operation is demonstrated with a Eu,Yb: KY(WO4)2 crystal on the 5D0 → 7F4 transition of the Eu3+ ion. When pumping into the 7F1 → 5D1 absorption band by a diode-pumped Nd3+:KGd(WO4)2/KTP laser power-scaled at 533.6 nm up to a watt-level, we achieved 2.5 mW of the continuous wave (CW) red output at ~702.1 nm. At quasi-CW pumping with a duty cycle of 10%, the peak power of the ms-long pulses arrived at ~19 mW, corresponding to a green-to-red conversion efficiency of 0.8%.

Microchip laser operation of Tm, Ho:KYW crystals with different ho concentrations

Tm, Ho co-doped crystals are prospective laser materials for realization of compact laser systems emitting at 2 μm, interesting for remote sensing and medical applications [1]. Recently [2, 3] diode-pumped microchip lasers on monoclinic double tungstate crystals co-doped with Tm3+ and Ho3+ions were demonstrated. However the study of influence different doping ions concentrations on laser characteristics in the same cavity configuration was not reported for these crystals. Considering complexity of the system where direct and back energy transfer [2], as well as up-conversion processes [4] take place, experimental study of the crystals with different content of doping ions is of high interest.

Thermal effects in eye-safe ring optical parametric oscillator based on KTiOPO 4 crystal

In eye-safe ring optical parametric oscillator (OPO) containing three KTiOPO4 crystals the crystal placed first in the path of pump radiation is subjected to the strongest thermal distortion caused by idler absorption. For the 10-Hz 35-mJ OPO, thermally induced lenses generate an increase in the signal beam divergence by 10% and moderate decrease in the signal energy.

Double-pass pumped extracavity optical parametric oscillator with passive optical feedback suppression

We demonstrate a simple way of building a compact eye-safe laser source based on a double-pass pumped extracavity optical parametric oscillator (EOPO) without an optical Faraday isolator. A Nd:KGW pump laser (PL) and the KTP EOPO located close to the PL are designed with stable cavities, while the 100% end system mirrors form an unstable cavity with sufficiently high threshold at 1067 nm. At the 6.6 J pump of the Nd:KGW laser, the EOPO output energy obtained at 1577 nm is 14.7 mJ, corresponding to the conversion efficiency of 33% with respect to the fundamental. The pulse width is 7 ns and the output beam divergence is 3 times diffraction limit.

Spectroscopic characterization of Eu 3+ :KY(WO 4 ) 2 laser crystal

Monoclinic Eu:KY(WO₄)₂ laser crystals are grown by TSSG method; polarization-resolved absorption and stimulated-emission cross-section spectra are determined for this crystal. Spectroscopic properties are modeled within ASCI theory. Under UV excitation, Eu:KY(WO₄)₂ provides intense red emission with CIE coordinates x = 0.670, y = 0.329.

Europium-Doped double tungstates: Novel crystals for visible lasers

Crystal growth, optical absorption and stimulated-emission are studied for Eu-doped monoclinic double tungstates, KRE(WO₄)₂ (with RE = Gd or Y). Free-running and Q-switched pulsed visible (702.8 nm, ⁵D₀→⁷F₄ transition) lasers, as well as quasi-CW and real-CW ones are realized with this crystal family, for the first time, to our knowledge.

Anisotropic absorption and luminescence and quasi-CW laser operation of Eu 3+ :KGd(WO 4 ) 2 monoclinic crystal

Present paper is devoted to the study of spectroscopic properties and laser potential of Eu-doped potassium gadolinium tungstate single crystal grown by TSSG technique (from the flux). It was motivated by recent realization of pulsed Eu:KGd(WO₄)₂ laser. As a result, quasi-cw Eu:KGd(WO₄)₂ laser operating at room temperature was demonstrated for the first time.

Eye-safe solid-state quasi-CW Raman laser with millisecond pulse duration

We demonstrate the first quasi-CW (ms-long pulses, pump duty cycle of 10%) end-diode pumped solid state laser generating eye-safe radiation via intracavity Raman conversion. The output power at the first Stokes wavelength (1524 nm) was 250 mW. A theoretical model was applied to analyze the laser system and provide routes for optimization. The possibility of true CW operation was discussed.