Abstract

Second-harmonic-generation frequency-resolved optical gating (SHG FROG) and cross-correlation frequency-resolved optical gating (XFROG) were used as a characterization method of pulses propagated through an optical medium. Time variation of intensity and phase of ultrashort pulses transmitting through a 0.5-mm-thick plate of Nd⁺³-doped glass were measured using these techniques. The results were compared with calculation by a linear theory, and it was confirmed that both of them are almost in agreement with the calculated result in the field intensity and phase. Autocorrelation measurement is one of die most popular pulse characterization methods. It provides information about the pulse width. However, recently, the technology for the creation of ultrashort laser pulses has progressed tremendously and now it is possible to create pulses even shorter than 5fs.[1-6] In experiments using these pulses, it is important to measure the pulse length in order to estimate the temporal resolution of a given experiment, but also important to get information about additional details of the pulse structure which may affect the experimental results substantially. One of the other pulse characterization methods is a fequency-resolved optical gating (FROG) technique. This FROG techniqueis often applied to characterization of ultrashort pulses [10], because it gives us information of both the intensity and phase profiles of the field. It is a great advantage compared to the autocorrelation method, thus it has become the most commonly used characterization method of ultrashort pulses. In this paper, we have died to study pulse propagation through a 0.5-mm-thick plate of Nd⁺³- doped glass, an optical medium which has a complicated structure in the laser spectral region, by fully characterizing the input and output pulses in such methods. SHG FROG and XFROG were employed and compared with calculation by a linear theory to confirm reliability of these methods.

© 2001 IEEE