Autocorrelation measurement of femtosecond laser pulses by use of a ZnSe two-photon detector array

Plasmonic enhanced two-photon absorption in silicon photodetectors for optical correlators in the near-infrared

A high-density array of plasmonic coaxial nanoantennas is used to enhance the two-photon absorption (TPA) process in a conventional silicon photodetector from a mode-locked 76 MHz Ti:sapphire laser over a spectral range from 1340 to 1550 nm. This enhanced TPA was used to generate an interferometric autocorrelation trace of a 150 fs laser pulse. Unlike second-harmonic generation, this technique does not require phase matching or a bulky crystal and can be used on a low-cost integrated silicon platform over a wide range of near-IR wavelengths compatible with modern commercial tunable femtosecond sources.

Double core-hole creation by sequential attosecond photoionization

X-ray fluorescence spectroscopy demonstrates that a single core-hole krypton with a 170-as lifetime can be photoionized again to a double core-hole state by an intense x-ray pulse. The observation indicates that unconventional interaction between intense x rays and atoms is no more negligible in applications with x-ray free-electron lasers. Quantitative analysis of the double core-hole creation including effects of a pulsed and spiky temporal structure enables estimation of the x-ray pulse duration in the sub-10-fs range.

Ultrashort laser pulse characterization using modified spectrum auto-interferometric correlation (MOSAIC)

Sensitive, real-time chirp and spectral phase diagnostics along with full field reconstruction of femtosecond laser pulses are performed using a single rapid-scan interferometric autocorrelator. Through the use of phase retrieval error maps, ambiguities in pulse retrievals based on the pulse spectrum and various forms of MOSAIC traces are discussed. We show second-order autocorrelations can introduce significantly different amounts of chirp depending on the implementation. Examples are presented that illustrate the sensitivity and fidelity of the scheme even with low signal-to-noise.

Interferometric correlation of infrared femtosecond pulses with two-photon conductivity in a silicon CCD

We present an experimental setup capable of performing a single-shot interferometric correlation of femtosecond pulses using two-photon conductivity in a standard silicon CCD camera. The method is demonstrated with 100-fs pulses at 1.4 microm.

Imaging and autocorrelation of ultrafast infrared laser pulses in the 3-11-mum range with silicon CCD cameras and photodiodes

Standard silicon photodiodes and CCD cameras are convenient and inexpensive alternatives to cryogenically cooled diodes or arrays for autocorrelation and imaging of ultrafast IR laser pulses in the wavelength range 3-11 mum . The response of these Si devices to IR pulses of duration ~100 fs is proportional to E(n) , where E is the pulse energy and n is approximately the Si electronic bandgap divided by the photon energy.