A Nested Folded 4f System for Ultra-Short Optical Pulse Shaping by Liquid Crystal Spatial Light Modulator

Abstract

In order to modulate the spectral phase properties of the ultra-short optical pulse in two dimensions by the liquid crystal spatial light modulator (LC-SLM), a setup named quasi-zero-dispersion nested folded 4f system is proposed, in which a grating disperses the ultra-short optical pulse frequency components in the vertical direction and a prism disperses the ultra-short optical pulse frequency components in the horizontal direction. Because the frequencies are dispersed in two directions, the LC-SLM is utilized more effectively and the optical frequency resolution for arbitrary temporal waveform generation is higher than the conventional zero dispersion 4f system. In theory, the quasi-zero-dispersion nested folded 4f system can generate arbitrary desired temporal waveform ultra-short optical pulse. Based on the system, Femtosecond pulse beam with Gaussian temporal waveform is used for experimentation, and an optical pulse train and several other temporal profiles were obtained. All the experimental results indicated that the quasi-zero-dispersion nested folded 4f system is reliable for arbitrary ultra-short optical pulse waveform generation, which fit well with the theoretical analysis. In the future, if a proper high dispersive optical element substitutes the prism in the quasi-zero-dispersion nested folded 4f system, the setup we proposed here will be widely used in the optical pulse shaping areas.