Recent progress toward real-time measurement of ultrashort laser pulses

Frequency-resolved optical gating (FROG) is a technique that produces a spe ctrogram of an ultrashort laser pulse optically, While a great deal of info rmation about the pulse can be gleaned from its FROG trace, often it is des irable to obtain all of the pulse information immediately, in real time. Qu antitative information about the pulse is not readily obtainable from its s pectrogram without the use of a two-dimensional phase retrieval algorithm. While current algorithms are quite robust, retrieval of all the pulse infor mation can be slow, In this paper, I describe a recently developed FROG tra ce inversion algorithm called Principal Component Generalized Projects that is fast, robust, and can invert FROG traces in real time. A femtosecond os cilloscope based on second-harmonic generation FROG is also described that uses this new algorithm to rapidly (up to 2.3 Hz) and continuously display the intensity and phase of ultrashort laser pulses.