ABSTRACT
We measure the temperature distribution of a 3 cm long periodically poled LiNbO3 crystal in a single-pass second harmonic generation (SHG) setup at 488 nm. By means of three resistance heaters and directly mounted Pt100 sensors the crystal is subdivided in three sections. 9.4 W infrared pump light and 1.3 W of SHG light cause a de-homogenized temperature distribution of 0.2 K between the middle and back section. A sectional offset heating is used to homogenize the temperature in those two sections and thus increasing the conversion efficiency. A 15% higher SHG output power matching the prediction of our theoretical model is achieved.
ABSTRACT
We study second-harmonic generation of picosecond pulses in bulk periodically poled lithium niobate using an all-semiconductor master oscillator-power amplifier with gain-switched seed as our fundamental source. Both during amplification and during the subsequent second-harmonic generation, the signal pulse shape improves, and the resulting pulses at 531 nm are nearly independent of the seed pump conditions. Over a wide range of repetition rates and seed settings, we obtain green pulses with a duration of less than 31 ps FWHM and a peak power of more than 5.1 W. We further investigate the influence of the fundamental's spectral dynamics on pulsed second-harmonic generation efficiency and obtain excellent agreement between our measurements and previously published theoretical treatments.
ABSTRACT
We demonstrate continues-wave 1 W at 490 nm on a 2.5 cm(3) micro-optical bench using single-path second-harmonic generation with a periodically poled MgO:LiNbO(3) bulk crystal. The pump laser is a distributed Bragg reflector tapered diode laser having a single-frequency spectrum and a pump power of 9.5 W. Based on that 1 W blue light could be achieved resulting in an optical conversion efficiency of 11%. Furthermore, the module has an output power stability of better than 2% and the blue laser beam shows an nearly diffraction limited beam quality of M(2)(sigma) = 1.2 in vertical and M(2)(sigma) = 2 in lateral direction.
