Highly efficient continuous-wave diode-pumped Er, Yb:GdAl_3(BO_3)_4 laser

Abstract

We report the highly efficient continuous-wave diode-pumped laser operation of Er, Yb:GdAl 3 BO 3 4 crystal. Absorption and stimulated emission spectra, emission lifetimes, and efficiencies of energy transfer from Yb 3 to Er 3 ions were determined. A maximal output power of 780 mW was obtained at 1531 nm at absorbed pump power of 4 W with slope efficiency of 26%. [12] a quasi-CW regime of operation was realized. However, the maximal CW output power did not exceed 250 mW with a slope efficiency of 27% [7].Comparatively recently, excellent laser performance of Er, Yb:YAl 3 BO 3 4 (YAB) crystal has been demonstrated. A diode-pumped Er, Yb:YAB laser exhibited a slope efficiency as high as 35% and output power of 0.8-1 W at several wavelengths between 1531 and 1602 nm [13,14].In this Letter, we present the spectroscopy and, for the first time to our knowledge, highly efficient diode-pumped CW laser operation of Er, Yb:GdAl 3 BO 3 4 (GdAB) crystal.Er, Yb:GdAB single crystals were grown by seeded high-temperature solution dipping. The concentration of Er x Yb y Gd 1−x−y Al 3 BO 3 4 with x 0.015 and y 0.11 in the initial load corresponded to 17 wt. %. As a result, Er, Yb:GdAB single crystals with high optical quality and sizes up to 20 mm × 10 mm × 10 mm were grown. The concentrations of the dopants were measured by microprobe analysis to be 1 at. % for Er 3 and 8 at. % for Yb 3 . The polarized absorption spectra of Er, Yb:GdAB crystal around 980 nm at room-temperature, recorded with a Cary-5000 spectrophotometer, are shown in Fig. 1. A strong absorption band corresponding to transition 2 F 7∕2 → F 5∕2 of Yb 3 ions is centered at 976 nm with a maximum absorption cross section of about 3.6 × 10 −20 cm 2 and bandwidth of 18 nm (FWHM) in σ polarization. Because of the comparatively broad absorption band, thermal control of the pump laser diode is not necessary. Figure 2 shows room-temperature polarized absorption spectra of Er, Yb:GdAB in the 1450-1650 nm spectral range (transition 4 I 15∕2 → 4 I 13∕2 of erbium ions). A number of local maxima are observed in both σ and π polarizations.For lifetime measurements an optical parametric oscillator (LOTIS LT-2214OPO) pumped by a Nd:YAG laser with pulse duration of 20 ns was used as an excitation source. The fluorescence decay was registered by an InGaAs photodiode and a 500 MHz digital oscilloscope. Fig. 1. Room-temperature polarized absorption spectra of Er, Yb:GdAB crystal at 1 μm.

Spectral-luminescent properties of vapor deposited Cr:ZnS thin films and their application as saturable absorbers for 15-μm erbium lasers

“…This material belongs to a family of erbium-ytterbium co-doped borate crystals [52,53] which are known for scaling the average power of 980-nm-pumped erbium lasers emitting around 1.55 μm beyond 1 W [54,55]. Crystal growth, spectroscopy, CW and Q-switched laser action with Er,Yb:GdAB have been reported recently [13,14,[56][57][58] showing a great potential of the material for the development of compact eye-safe lasers for real-life applications.…”

Laser Performance of Er,Yb:YAl3(BO3)4 Crystals with Different Erbium Concentrations

“…CW room-temperature laser operation was demonstrated for the following Er,Yb-codoped oxoborate crystals: GdCa 4 O(BO 3 ) 3 [2], LaSc 3 (BO 3 ) 4 [3], YCa 4 O(BO 3 ) 3 [4]; while for Li 6 Y(BO 3 ) 3 [5], Sr 3 Y 2 (BO 3 ) 4 [6], Sr 3 Gd 2 (BO 3 ) 4 [7], and LuAl 3 (BO 3 ) 4 [8] quasi-continuous-wave regime of operation was realized. Comparatively recently, excellent laser performance of Er,Yb-codoped YAl 3 (BO 3 ) 4 (YAB) and GdAl 3 (BO 3 ) 4 crystals was demonstrated [9,10]. Diode-pumped Er,Yb:YAB laser exhibited a slope efficiency as high as 35 % and output power up to 1 W at several wavelengths between 1522 and 1602 nm .…”

High Power Diode-Pumped Erbium Laser Emitting at Near 1.5 μm

“…The borate crystals co-doped with erbium and ytterbium ions satisfy abovementioned spectroscopic characteristics and possess high thermo-mechanical properties (thermal conductivity of Er,Yb:YAl 3 (BO 3 ) 4 is 7.7 W×m −1 ×K −1 and 6 W×m −1 ×K −1 along a and c axes, respectively) for efficient laser operation [3]. Room-temperature laser operation was demonstrated for following Er,Yb-codoped borate crystals: GdCa 4 O(BO 3 ) 3 [4], LaSc 3 (BO 3 ) 4 [5], YCa 4 O(BO 3 ) [6], GdAl 3 (BO 3 ) 4 [7,8], LuAl 3 (BO 3 ) 4 [9]. Efficient high power laser performance of diodepumped Er,Yb:YAl 3 (BO 3 ) 4 (YAB) crystals was demonstrated recently [10−12].…”