Abstract

Optical nonlinearities limit the maximum power that can be transmitted through an optical fiber transmission system.¹ The intensity dependent refractive index, n₂, leads to a phase modulation within a single optical pulse. In a technique developed by Stolen et al.,² a transform limited optical pulse is coupled into a fiber and the output spectrum is measured. As the input power is increased, maxima and minima of the central peak occur in the frequency spectrum at integer orders of π/2. From the known phase shift a value for n₂ can be deduced. In these experiments, the typical input pulsewidths are approximately 100 ps and the fiber lengths range from 100-250 meters in order to achieve several orders of π/2 phase shift. Utilizing photorefractive beam coupling, we can easily detect a phase-modulated optical pulse in the time domain, using 50-ps pulses and a 24-m length of fiber.

© 1993 Optical Society of America