The Measure of Phase of Ultrashort Light Pulse by using a Spectrally Resolved Autocorrelation

• Main Authors: LIN, JING YUAN, 林靖淵
• Other Authors: HUANG, SHENG LUNG
• Format: Others
• Language: en_US
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/12553631543620768207

碩士 === 國立中山大學 === 光電(科學)研究所 === 83 === Recent progress in the field of ultrashort pulsed laser led to the development of stable sources generating a continuous train of pulses with less than 1 ps in duration. Since electronic detection techniques are still limited at around 10 ps, there is a need to resolve both phase and amplitude of the ultrashort pulses. Consequent, the measurement of the complex electric field of ultrashort light pulse is highly desirable to obtain complete information on their amplitude and phase. The common means of intensity autocorrelations and spectral measurements do not provide any information on the phase of the measured pulse. In the thesis, a method relies only on the measurement of a spectrally resolved autocorrelation (SRA) is studied. The SRA signal is obtained simply by measuring the spectrum of the second-harmonic pulse at the output of a conventional intensity autocorrelator. This spectrum as a function of delay between the two arms of the autocorrelator yields a two-dimensional data set. An iterative algorithm is used to retrieve the complex electric field ( amplitude and phase) from the information provided by its SRA. We believe that the method described and demonstrated here can be applied in a simple and reliable way to determine the actual shapes and phases of ultrashort laser pulses. And it will be useful for pulses that are too weak to be measured by other third-order phase retrieval techniques.