Abstract

Recent advances in optical pulse compression have made possible the production of pulses as short as 8 fs,¹ corresponding to only 3.8 cycles duration. Several interesting optical problems arise as a result of the large bandwidth which is characteristic of such short pulses. The generation of the large chirped bandwidth by propagation of an intense pulse in a short length of optical fiber appears to still be well described by the nonlinear Schrödinger equation,² however in the compression using parallel diffraction gratings it is no longer valid to neglect the cubic phase term.³ Inclusion of this term alters considerably the compressed pulse characteristics. The dispersion of optical materials is not exactly linear with frequency, and this introduces another frequency dependent error which can affect the compressed pulse. In addition to these problems which arise in generation of very short pulses, a number of problems are encountered in manipulation of the pulse. A number of common optical elements such as wave plates and multilayer dielectric coatings are essentially useless in this regime. In fact, propagation of an 8-fs optical pulse through only a few meters of air produces significant pulse broadening.

© 1985 Optical Society of America