Generation of ultra short mid-infrared pulses by super continuum seeded OPA in a MgO: LiNbO_3 crystal

摘要

A type I phase matching MgO:LiNbO_3 optical parametric amplification (OPA) system were demonstrated. The OPA system was synchronously seeded with a super continuum and pumped by a laser pulse of 1Hz, 55fs, 3.5mJ, centered at 812nm. The super continuum was got by a sapphire plate and the MgO:LiNbO_3 crystal which was 30mm×30mm×15mm in size. In order to avoid the three waves' temporal walk-off, pump wavelength and seeded signal wavelength were tuned simultaneously in simulation, and the result was that it can't be avoided in the collinear phase matching OPA. For the purpose of compensating the group velocity's mismatching, the non-collinear phase matching was adopted, then the non-collinear angles and the best amplified signal wavelengths which changing with the pump wavelengths were also optimized in numerical simulation for the non-collinear phase matching OPA. As a result, pulse energy of as much as 126uJ was achieved at wavelengths ranging from 3.2μm to 4.3μm.