Stable, high-power, continuous-wave, single-frequency source at 532 nm using MgO:sPPLT crystal S. Chaitanya Kumar 1,* , G. K. Samanta 1 and M. Ebrahim-Zadeh 1, 2 1 ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Barcelona, Spain 2 Institucio Catalana de Recerca i Estudis Avancats, Passeig Lluis Companys 23, Barcelona 08010, Spain E-mail: chaitanya.suddapalli@icfo.es Abstract: We describe a compact, high-power, cw green source based on single-pass SHG of a Yb-fiber laser in MgO:sPPLT, providing 7.58W, single-frequency output at 532nm in TEM oo profile(M 2 <1.29) with peak-to-peak power stability of 9% over 13h. © 2008 Optical Society of America OCIS codes: 190.4970, 190.4360, 190.4400, 1902620, 190.7220, 140.7300. High-power, continuous-wave (cw), single-frequency green sources are of interest for variety of scientific and technological applications, including pumping of Ti:sapphire lasers and cw singly-resonant optical parametric oscillators (SROs) pumped in the visible [1]. To date, such sources have been based almost exclusively on internal second-harmonic-generation (SHG) of cw Nd:YAG and Nd:YVO 4 solid-state lasers, where the attainment of stable, high-power, and single-frequency performance necessitates elaborate system designs involving intricate cavity configurations, thermal management, and active stabilization, resulting in complexity and high cost. It would, thus, be desirable to devise alternative approaches for the development of such sources using more simplified and cost- effective techniques. An attractive approach is external SHG of high power infrared lasers in quasi-phase-matched (QPM) ferroelectric materials such as MgO:PPLN [2], MgO:sPPLT [2,3], and PPKTP [2,4], of which MgO:sPPLT has demonstrated the most promise due to its high photorefractive damage threshold and large thermal conductivity to handle high optical powers. Earlier reports on green generation in MgO:sPPLT include external single-pass SHG of a 91.5-W cw Nd:YAG laser, providing a maximum power of 16.1 W at 17.1% conversion efficiency [3]. However, the development of high-power, cw, single-frequency sources in the green based on cw fiber laser technology and offering high output power stability, spatial beam quality, mandatory requirements for the above applications, has not been extensively explored. Here we describe such a source using a simple, compact, and cost- effective design based on external single-pass SHG of a cw Yb fiber laser in MgO:sPPLT. The source can deliver 7.58 W of cw, single-frequency green power at 532 nm with a conversion efficiency as high as 25.6%, peak-to-peak power stability of 9% over 13 hours, and TEM oo spatial profile. The configuration of the experimental setup is identical to our previous work [4]. The nonlinear crystal is MgO:sPPLT (d eff ~10 pm/V). It is 30-mm long, with a single grating period of Λ=7.97 μm, and is housed in an oven with a temperature stability of ±0.1 o C. The crystal faces are antireflection (AR) coated (R<0.5%) for the fundamental (1064 nm), and high transmission (T>99%) at second harmonic (532 nm) wavelength. The pump Fig. 1. Dependence of the measured cw SHG power and the corresponding conversion efficiency on the incident fundamental power. Inset: Variation of SH power as a function of square of the fundamental power. Fig. 2. Dependence of the measured quasi-cw SH power and the corresponding conversion efficiency on the incident fundamental power. Inset: Variation of SH power as a function of square of the fundamental power. 0 5 10 15 20 25 30 0 2 4 6 8 0 5 10 15 20 25 30 0 5 10 15 20 25 30 SH Power (W) Fundamental Power (W) 0 300 600 900 0 2 4 6 8 0 300 600 900 0 2 4 6 8 SH Power (W) [Fundamental Power (W)] 2 Efficiency (%) 0.0 0.1 0.2 0.3 0.4 0.0 0.5 1.0 1.5 0 5 10 15 20 25 Average SH Power (W) 0.0 0.5 1.0 1.5 2.0 2.5 0.0 0.1 0.2 0.3 SH Power (W) [Fundamental Power (W)] 2 Efficiency (%) Average Fundamental Power (W) a775_1.pdf CThZ3.pdf © 2009 OSA/CLEO/IQEC 2009 CThZ3.pdf