Compact in-line temporal measurement of laser pulses with amplitude swing.

A method of ultrashort laser pulse reconstruction is presented, consisting on the analysis of the nonlinear signal obtained from the interference of the pulse with a replica of itself at a given time delay while varying the relative amplitude between the pulses. The resulting spectral traces are analyzed both analytically and numerically, showing the encoding of the input pulse spectral phase. A reconstruction algorithm is discussed and applied to extract the spectral phase and, jointly to the measured spectral amplitude, reconstructing the pulse. In order to validate the technique, an experimental in-line implementation of the characterization concept is compared to the results from a stablished technique, obtaining a good agreement at different input pulse cases. In sum, a new technique is presented, showing the capability to reconstruct a broad range of temporal pulse durations while its implementation is robust and straightforward, able to be easily adapted to diverse pulse duration and central wavelength ranges.

Strategies for achieving intense single-cycle pulses with in-line post-compression setups.

Intense few- and single-cycle pulses are powerful tools in different fields of science Today, third- and higher-order terms in the remnant spectral phase of the pulses remain a major obstacle for obtaining high-quality few- and single-cycle pulses from in-line post-compression setups. In this Letter, we show how input pulse shaping can successfully be applied to standard post-compression setups to minimize the occurrence of high-order phase components during nonlinear propagation and to directly obtain pulses with durations down to 3 fs. Furthermore, by combining this pulse shaping of the input pulse with new-generation broadband chirped mirrors and material addition for remnant third-order phase correction, pulses down to 2.2 fs duration have been measured.