Stable High-Power Green Light Generation with Thermally Conductive Periodically Poled Stoichiometric Lithium Tantalate

Abstract

Periodically poled stoichiometric lithium tantalate was used for an efficient green light generation based on frequency doubling of a pulsed Nd:YVO 4 laser. The achieved average peak power density of 9.2 MW/cm 2 was sufficiently stable without spatial distortion of green light at 532 nm at room temperature (33 C). A small phase matching temperature adjustment (0.5 C) was required at the maximum average output power of 4.4 W owing to its high thermal conductivity.

Optical Application of Domain Engineering: Polarization-Reversed Optical Devices

“…The large aperture devices again produced high output power 4.4 W in green (Fig. 7), by single pass second harmonic generation (SHG) for the laser pulse parameters of 4.9 ns and 8.3 kHz [10]. No photorefractive damage was observed at room temperature owing to 1 mol% Mg doping.…”

Growth of 4-in diameter MgO-doped near-stoichiometric lithium tantalate single crystals and fabrication of periodically poled structures

“…SLT (Li-49.9 and Ta-50.1 mol%) crystals show a larger EO and NLO constants [2][3][4] and a wider transparent range ($20 nm in UV) [5] than common CLT. Thus, the stoichiometric LT is a potential candidate for QPM applications.…”

“…An alternative way to suppress the photorefractive damage is, through suitable doping of the crystal itself with MgO. Stable second harmonic generation (SHG) and optical parametric oscillation (OPO) based on periodically poled MgO-doped SLT crystals have been demonstrated with a slope efficiency of 65% [4,7,8]. The efficiency can be further improved by increasing the device length.…”

Optical breakdown threshold in nanosecond high repetition second harmonic generation by periodically poled Mg-doped LiTaO3 crystal

“…9 Models of laser frequency conversion adjusted to include these effects often disagree with the experimental data and continue to remain a focus of research. [10][11][12][13][14][15][16][17] Optical breakdown in dielectrics is generally attributed to generation of free electrons heated afterwards to a kinetic energy sufficient for impact ionization. 6,18,19 Short ps and fs pulses are known to produce a strong non-equilibrium between free electrons and crystal lattice enabling the electrons to achieve an energy sufficient for the onset of impact ionization, electron emission, material modification, and damage.…”

“…9,10 In conducting the simulations shown in Figs. 1-3, we use (i) effective non-linearity d eff ¼ 10 pm/V, 12 (ii) linear photo-absorption coefficients: 2 a 1 % 0.002 cm À1 (for k 1 ¼ 1064 nm) and a 2 % 0.025 cm À1 (for k 2 ¼ 532 nm), and (iii) in view of 2 hx 2 % 4:66 eV which is very close to SLT energy band gap, E g ¼ 4.6 eV, the TPA coefficient is estimated as b % 2r ð 2Þ ng N Ã = hx 2 % 2.55 Â 10 À9 cm/W via the resonant TPA cross section, r ð 2Þ ng % 2.5 Â 10 À50 cm 4 s/photon 2 , 1 and molecular density N Ã ¼ N a =5 % 1.9 Â 10 22 cm À3 (where N a % 9.5 Â 10 22 cm À3 is the atomic density of LiTaO 3 ). SHG simulation made by using this value of b and presented in Fig.…”