Arbitrarily shaped picosecond pulses by spectral compression of femtosecond pulses in engineered quadratic media

This work shows that in suitably designed engineered quasi-phase-matching structures, second harmonic SH pulses with transform-limited picosecond duration and predetermined spectral and temporal shape can be generated with high efficiency. The design was accomplished in a second-order quasi-phase-matching scheme and it was finalized to the synthesis of the following three SH target pulses centred at a 700 nm wavelength: a) Gaussian pulse with 2.2 ps duration, b) super-Gaussian pulse with 5 ps duration, c) pair of two 3-ps-long super-Gaussian phase-coherent pulses with a 200 cm^-1 carrier-frequency offset.