Distortion-free temporal profiling of chirped picosecond laser pulses by spectral shaping with opaque solid masks

Abstract

We propose a method for laser pulse temporal shaping applying just an opaque solid 2D mask as a shaping element. The research is motivated by recent experimental data on temporal distortions produced in chirped picosecond pulses by spatial light modulators (SLMs) commonly used in shaping schemes and consequent demand for alternative solutions.In the presented scheme, the effect of grey-level masking in the spectral domain is achieved by dimensional reduction from 2D shaping on air to 1D obtained modulation at the fiber output. The mask is placed in the Fourier plane of a compressor with zero frequency dispersion. Instead of a spherical telescope in the compressor, a cylindrical one is used. Due to large linear chirp in the input pulse, spectral profile corresponds to the temporal distribution.We demonstrated in the experiment conversion of a 40 ps bell-shaped pulse into a rectangular pulse, demanded, for example, in photoinjector technology. Our scheme showed itself as a cheap and easy alternative to SLM shaping, therefore we believe it can be interesting for some applications.

Shaping ellipsoidal laser pulses in the scheme with black analog masks for photoinjector applications

“…The resulting pulse is a product of three mutually orthogonal 2D elliptical cuts, which is rather close to the ellipsoidal shape. Since 3DESP definition assumes constant intensity inside, temporal [15][16][17] and transversal pre-shaping stages should be added to the final shaper layout, but they were skipped in this work for simplicity.…”