Two-photon Self-related Picosecond Pulse Detection Studies

With the development of mode-locked Laser, the pulse's width becomes narrower and narrower, and exhibits more and more applications in many fields. Obviously, these developments and applications demand improvements of measurement of pulse. In order to study on ultra short pulse precisely, some measurement methods are established, such as second order autocorrelation, frequency-resolved optical gating(FROG), self—referencing spectral phase interferometry for direct electric reconstruction (SPIDER).Some usual measurement methods are introduced, and their advantages and disadvantages are also analyzed in detail. In view of the defects of the usual methods and the latest developments in bi-photon effect, an all-fiber-measurement system for ultra short pulse was designed in this work, based on the knowledge of nonlinear fiber optics, application of passive optic apparatus, optic-electric transformation, analog circuit, micro chip unit(MCU) and so on. The fundamental principle of this system is as follows. Divide the incident beam into two beams, one of which passing through variable optical delay(VOD), Then combination of the two beams with the same amplitude and delay-superposition is sent to bi-photon detector and transformed into current signals, whose intensity is proportional to the intensity of bi-photon autocorrelation signals. Modification of the delay time may likewise alter the intensities of current and autocorrelation signals, and then result in autocorrelation curve. Therefore, the width of the pulse can be obtained through calculations and treatments. Compared with the usual methods, this system is compact and convenient, and applicable to the pulses with low power.The arrangements of this thesis are as follows:(1) The common measurements are introduced systemically and compared in detail, including second order autocorrelation, FROG and SPIDER in Chapter1 and Chapter2.(2) The principles of bi- photon autocorrelation measurement of the width of the picosecond pulses are described and the schemes based on the principles are...