High Peak Power, Passively Q-Switched Yb:YAG/Cr:YAG Micro-Lasers

Author

Tsunekane, Masaki ; Taira, Takunori

Author_Institution

Laser Res. Center, Inst. for Mol. Sci., Okazaki, Japan

Volume

49

Issue

5

fYear

2013

fDate

41395

Firstpage

454

Lastpage

461

Abstract

A high peak power (>MW), passively Q-switched Yb:YAG/Cr:YAG micro-laser end-pumped by fiber-coupled 120-W QCW LDs (Repetition rate <; 100 Hz) is developed. The convex output coupler with a curvature of -2 m successfully enlarges the fundamental mode size in the micro-laser cavity, and the output pulse energy increases to 3.6 mJ at a Cr:YAG initial transmission of 89% without optical damage. The TEM₀₀ transverse mode and the single-frequency oscillation are confirmed. The pulse duration is 1.3 ns, and then the peak power is estimated as 2.8 MW. To our knowledge, these are the highest pulse energy and peak power ever reported in Yb:YAG/Cr:YAG micro-lasers. The Yb:YAG rod with 5 at.% Yb concentration and 4.2-mm thickness keeps more than 80% single-pass pump absorption ranging from 15°C to 45 °C in LD temperature. On the other hand, the characteristic temperatures of Yb:YAG/Cr:YAG and Nd:YAG/Cr:YAG lasers were estimated as 110 and 278 K, respectively. This means that the ratio of the increase in threshold pump energy to temperature of a Yb:YAG/Cr:YAG laser is twice or higher than that of a Nd:YAG/Cr:YAG laser due to a quasi-3-level system of Yb:YAG.

Keywords

Q-switching; chromium; infrared spectra; laser beams; laser modes; light absorption; light transmission; microcavity lasers; optical couplers; optical pumping; solid lasers; ytterbium; LD temperature; TEM₀₀ transverse mode; YAG:Yb-YAG:Cr; characteristic temperature; convex output coupler; energy 3.6 mJ; fiber-coupled QCW LD; fundamental mode size; high peak power passively Q-switched microlasers; microlaser cavity; output pulse energy; power 120 W; power 2.8 MW; pulse duration; quasi3-level system; single-frequency oscillation; single-pass pump absorption; size 4.2 mm; temperature 110 K; temperature 15 degC to 45 degC; temperature 278 K; threshold pump energy; time 1.3 ns; Absorption; Couplers; Laser beams; Laser excitation; Laser modes; Measurement by laser beam; Pump lasers; Cr:YAG; Yb:YAG; diode pump; ignition; passively Q-switched lasers; solid-state lasers;

fLanguage

English

Journal_Title

Quantum Electronics, IEEE Journal of

Publisher

ieee

ISSN

0018-9197

Type

jour

DOI

10.1109/JQE.2013.2252327

Filename

6482165