All-solid-state high-repetition-rate optical source tunable in wavelength and in pulse duration

A synchronously pumped optical parametric oscillator (OPO) employing periodically poled lithium niobate (PPLN) efficiently generates diffraction-limited short pulses that are tunable in the 1.45–1.56-µm spectral range, with their duration adjustable from ≈1 ps–15 ps and output power as high as 630 mW. The pump laser that produces these unique OPO characteristics is a 200-MHz, 2.5-W average power, diode-pumped Nd:YVO4 laser emitting at 1064 nm and passively mode locked by a nonlinear mirror (NLM) technique. One can select the output pulse width from the vanadate laser to be either 16 or 6 ps simply by choosing the appropriate NLM configuration. Significantly enhanced performance of the mode-locked Nd:YVO4 laser was obtained with a critically phase-matched type I LiB3O5 crystal. A comparison of this crystal with type II KTiOPO4 is reported.