Continuous-wave Laser on Er,Yb-Codoped Pentaborate Crystal

Abstract

We report, for the first time to our knowledge, a diode-pumped continuous-wave microchip Er,Yb:YMgB 5 O 10 laser. The purpose of this work was to study the growth technique, spectroscopic properties and continuous-wave laser performance of Er 3+ ,Yb 3+ :YMgB 5 O 10 novel crystal.Absorption and luminescence spectra as well as kinetics of luminescence decay were studied. Ytterbiumerbium energy transfer efficiency was determined. The output characteristics (output power, slope efficiency, laser wavelength) of Er 3+ ,Yb 3+ :YMgB 5 O 10 laser were determined.Two intensive absorption bands with peaks centered at 937 nm and 976 nm were observed in the absorption spectra at the wavelength near 1 µm. The maximum value of absorption cross-section was determined to be 1.5·10 -20 cm 2 at 976 nm for polarization E//N g . A number of narrow lines were observed in the absorption spectra in the 1425-1575 nm spectral range (transition 4 I 15∕2 → 4 I 13∕2 of erbium ions). The lifetime of the upper laser level 4 I 13/2 of Er 3+ ions was determined to be 390 ± 20 μs. The ytterbiumerbium energy transfer efficiency for YMgB 5 O 10 crystal with 2 at.% of Er 3+ and 11 at.% for Yb 3+ was close to 84 %. The maximal continuous-wave output power of 0.2 W with slope efficiency of 8 % regarding to absorbed pump power was realized at the wavelength of 1570 nm. With the improvement of cavity parameters the output laser performance of the Er,Yb:YMgB 5 O 10 crystal can be further enhanced.Taking into account high thermal conductivity of ≈ 6.2 W·m -1 ·K -1 , the Er,Yb:YMgB 5 O 10 crystal can be considered as a good gain medium for 1.5 μm lasers for applications in laser rangefinder and LIDAR systems.