Optical pulse compression to 5.0 fs using only the spatial light modulator

Summary form only given. Optical pulses in the 5-fs region have been generated using chirped mirrors for chirp compensation. Chirped mirrors have the advantage of high throughput. However, the difficulty of obtaining a very large bandwidth, the inter-dependence of different phase orders, and the inability to fine-tune the phase in the experimental set-up are disadvantages. On the other hand, the pulse shaping technique (Weiner et al, IEEE J. Quantum Electron. vol. 28, p. 909, 1992) using a liquid crystal spatial light modulator (SLM) for pulse compression has the advantages of large bandwidth (300-1500 nm) and in-situ adaptive phase control. Recently it was used to compress broadband pulses with pre-chirp compensation by the prism pair to obtain sub 6-fs pulses (Xu et al, 2000). Here, we demonstrate experimentally that the pulse shaper with the SLM can be used to compress broadband (500-1000 nm) pulses from the argon-filled capillary fiber without any pre-chirp compensation to generate 5.0-fs pulses. By not using any pre-chirp compensation optics, the optical throughput increases, the alignment becomes easier and the total spectral width is not cut. Also, the important parameter of the phase pattern applied by the SLM for generating pulses close to the transform-limit is identified. To accurately evaluate the pulses thus generated, second-harmonic frequency-resolved optical gating (SH-FROG) is used.