Abstract

Passively modelocked solid-state lasers provide ultrashort pulses with high power and stability. Scaling these lasers to higher repetition rates, important for many applications, presents several challenges in terms of nonlinearity, dispersion management, and damage from instabilities. Modelocking with cascaded quadratic nonlinearities can offer solutions to each of these problems simultaneously [1-3]. Here we experimentally demonstrate a new and promising regime of cascaded quadratic interactions, enabled by an apodized, fan-out quasi-phasematching (QPM) device, whereby the second harmonic (SH) is adiabatically excited and de-excited within the crystal. This enables a large nonlinear refractive index by operating close to phase-matching, while minimizing losses for the laser pulse.

© 2015 IEEE