Generation and Optimization of Femtosecond Pulses by Four-Wave Mixing Process

Four-wave mixing (FWM) was used to generate and optimize ultrashort pulses with wavelengths from ultraviolet (UV) to near-infrared in bulk media and gases. Wavelength-tunable multicolored pulses were simultaneously generated by cascaded FWM in glass plates. By using incident chirped pulses, 15-fs self-compressed multicolored pulses were obtained with excellent properties. Self-compression was also used to generate ultrashort deep-UV (DUV) pulses. The positive frequency chirp in a self-phase-modulated pulseissuitable for this objective. Sub-10-fs DUV pulses were generated without using any additional pulse compressors. Self-diffraction was used to clean the pulse, broaden the spectrum, and enhance the spatial beam quality. These multicolored pulses can be simultaneously amplified and compressed by a four-wave optical parametric amplifier. The generated multicolored pulses are useful for multicolored ultrafast spectroscopy, microscopy experiments, and as seeds for petawatt lasers with high temporal contrasts.