APE autocorrelators are used to measure the pulse duration of femtosecond and picosecond laser systems. The technology is based on either Second Harmonic Generation (SHG) detection or Two Photon Absorption (TPA) detection principle.
The pulse duration, also called pulse width, of a laser beam source is defined as the interval between the two points in time at which the instantaneous power of the pulse reaches 50% of the peak power for the first and last time.
The sensitivity of an autocorrelator is the minimum amount of input signal required to generate a specified autocorrelation signal. The specified sensitivity is defined as the average power multiplied by the peak power of the incoming pulses and is usually expressed as W2.
Depending on the laser parameters it is not always advantageous to use detectors with high sensitivity, for example to prevent saturation of the detectors. Our APE staff will be happy to advise you on the selection of a suitable detector.
PMT, PD, or TPA: For pulse measurement with extreme sensitivity and low pulse energy, we recommend our photomultiplier (PMT) detector. Spectrally enhanced photodiodes (PD, TPA), on the other hand, are the ideal choice for measurements requiring sensitivities of a few mW2.
