Abstract

We have recently observed pulse length preserving two-beam coupling of 40-fs pulses from a colliding-pulse mode-locked laser.¹ At first, it might be thought that because the pulses are only about 5-μm long in the crystal and interfere only in a very narrow (approximately 100-μm-wide) slide of the crystal, the diffraction efficiency could not be very high. But it turns out that the Fresnel reflectivity from each of the grating fringes is high enough to compensate for the fact that the number of grating periods is only twice the number of optical cycles in the interacting pulses.

© 1991 Optical Society of America