摘要
We extend the technique of difference-frequency mixing of broadband chirped near-infrared (IR) pulses to longer wavelengths, thereby generating high-energy, bandwidth-tunable laser pulses in the mid-IR spectral region. Numerical modeling has been performed to examine the influence of pump and seed chirp on the generated idler bandwidth and pulse duration. The amplifier is realized using zinc-germanium phosphide crystals pumped by a 2 μm ultrafast parametric source. Idler pulses at a center wavelength of 5 μm with adjustable bandwidth are produced by equally chirping the pump and seed pulses using material dispersion. Using this simple approach, efficient generation of narrowband, short, mid-IR laser pulses is achieved without the use of high-loss dispersive gratings or prism pairs.