Simultaneous generation of second-harmonic light with orthogonal polarizations in the blue spectral region is demonstrated by use of typeII and typeI quasi-phase matching for the nonlinear coefficients d<sub>33</sub> , d<sub>24</sub> , and d<sub>32</sub> in periodically poled KTP. The second-harmonic power ratio in both polarization states can be tuned by the fundamental polarization and (or) the periodically poled KTP temperature. Femtosecond pulse frequency-doubling efficiencies of as much as 39.5% W <sup>-1</sup> and 8.1% W <sup>-1</sup> are demonstrated in 7-mm periodically poled KTP for typeI and typeII processes, respectively. The efficiency limitations caused by various effects of the group-velocity mismatch are discussed.
© 2002 Optical Society of America
V. Pasiskevicius, S. J. Holmgren, S. Wang, and F. Laurell, "Simultaneous second-harmonic generation with two orthogonal polarization states in periodically poled KTP," Opt. Lett. 27, 1628-1630 (2002)