We report, for the first time to our knowledge, a diode-pumped cw and passively Q-switched microchip Er, Yb:YAl(3)(BO(3))(4) laser. A maximal output power of 800 mW at 1602 nm in the cw regime was obtained at an absorbed pump power of 7.7 W. By using Co(2+):MgAl(2)O(4) as a saturable absorber, a TEM(00)-mode Q-switched average output power of 315 mW was demonstrated at 1522 nm, with pulse duration of 5 ns and pulse energy of 5.25 μJ at a repetition rate of 60 kHz.

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.

We report for the first time, to the best of our knowledge, on a diode-pumped passively Q-switched Er,Yb:GdAl3(BO3)4 laser. By using a Co2+:MgAl2O4 crystal as a saturable absorber, Q-switched laser pulses with a duration of 12 ns and a maximum energy of 18.7 μJ at a repetition rate of 32 kHz corresponding to an average output power of 0.6 W were obtained at 1550 nm under continuous-wave pumping. In the burst mode of operation, Q-switched laser pulses with the highest energy up to 44 μJ were realized with a pulse repetition rate of 6.5 kHz.

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We demonstrate a passively Q-switched Er,Yb:GdAl 3 (BO 3 ) 4 diode-pumped laser emitting near 1.5 µm. By using a single-walled carbon nanotube (SWCNT) as a saturable absorber, Q-switched laser pulses with energy of 0.8 µJ and duration of 130 ns at a maximum repetition rate of 500 kHz were obtained at 1550 nm.