Broadening of the second-harmonic phasematching bandwidth in type II periodically poled KTP

We have theoretically demonstrated type II broadband second-harmonic generation (SHG) based on a quasi-phase-matching (QPM) configuration in periodically poled KTP (PPKTP). The wavelength dependence of QPM grating periods at different temperatures of 5 (degree)C, 25 (degree)C, and 45 (degree)C is calculated with the crystal length of 1 cm. We find a very wide bandwidth, as large as 42.6 nm, of fundamental wavelength of 1.58 (mu)m at the telecommunication band with the QPM period of 48.9 (mu)m at 25 (degree)C. The corresponding bandwidths of incident angle and temperature are found to be 4.24(degree) and 14.8 (degree)C, respectively. The comparison among PPKTP, periodically poled lithium niobate (PPLN), and MgO:PPLN reveals the unique performance of PPKTP in the broadband SHG.