Temporal contrast degradation at the focus of ultrafast pulses from high-frequency spectral phase modulation

摘要

The impact of high-frequency spectral phase modulation on the temporal contrast of ultrafast pulses is evaluated. Expressions are derived for the low-intensity pedestal produced by optical component surface roughness within pulse stretchers and compressors. Phase noise, added across the near-field of a spectrally dispersed beam, produces space-time coupling in the far-field or focal plane. The pedestal is swept across an area in the focal plane many times the size of the diffraction-limited spot. Simulations are performed for generic stretchers and compressors that show fundamentally different forms of temporal contrast degradation at focus.