Abstract: A system for characterizing a pulse of electromagnetic radiation by time-resolved optical gating, which includes an interference-forming device which is adapted for superimposing four parts of the pulse. The system also includes a matrix image sensor which selectively captures, based on two-photon absorptions, an interference pattern formed by the pulse. The system allows obtaining the pulse shape completely and accurately, and is particularly suitable for characterizing ultrashort pulses. Also, the two-photon absorption can be produced in the matrix image sensor, or replaced by optical frequency doubling which is produced by an SHG crystal plate.

Abstract: A method and a device for detecting a resonant non-linear optical signal induced in a sample including a resonant medium and a non-resonant medium forming an interface is disclosed. The device includes an excitation light beam that intercepts the sample along an optical axis. The device further includes a first optical detection module for detecting a nonlinear optical signal resulting from the interaction of the beam with the sample, and a mirror that reflects the excitation beam. The device further includes a second optical detection module for detecting a nonlinear optical signal resulting from the interaction of the reflected excitation beam with the sample, and a processing module for processing the optical signals, detected by the first and second detection modules. Processing the optical signals includes calculating a difference in the detected signals, the difference being characteristic of a vibrational or electronic resonance of the resonant medium.

Abstract: The invention relates to a method and a device for detecting a resonant non-linear optical signal induced in a sample (805) comprising a resonant medium (61) and a non-resonant medium forming an interface, the device comprising: an emission source (801) of at least one first excitation light beam of a resonant medium, called a pump beam, at a first given angular frequency ?p, said pump beam being incident on a sample along an optical axis, and intercepting the sample at a given position of a transverse interface between the resonant and non-resonant medium, a first optical detection module (803) for detection of the nonlinear optical signal resulting from the interaction of said beam or beams with the sample, means of reflection (813) of said excitation beam or beams, the excitation beam or beams thus reflected intercepting said transverse interface substantially at the same position as the incident excitation beam or beams, a second optical detection module (806) for detection of the nonlinear optical sig