Light source technology: Fourier synthesis of optical pulses

Abstract

With the rapid progress made recently in the field of optical communication technology, much attention is being focused on the techniques for generating ultrafast optical pulses with an ultra-high repetition frequency. Fourier synthesis is one of the most promising techniques for doing this, because, unlike in conventional techniques such as mode-locking, there is no limitation on having an arbitrarily high repetition frequency. Fourier synthesis is also used to synthesize arbitrary waveforms based on the inverse process of Fourier-series expansion. The generation of ultrafast optical pulses has been demonstrated with repetition frequencies from 9.6 GHz to as high as 1.8 THz by synthesizing the outputs from three independently oscillating semiconductor lasers. It has also been demonstrated that the Fourier-synthesized pulses could be synchronized to an external optical clock. This paper describes the outlines of the above experiments as well as a technique for successive generation of arbitrary bit streams.