Abstract

Future lightwave communication systems may exploit the practically unlimited bandwidth of optical fiber via densely packed wavelength- division multiplexing (WDM) with aggregate throughput exceeding hundreds of gigabits per second. In such systems, it is essential to identify and control a large number of channels expeditiously. This can be achieved by using a master oscillator which provides an absolute frequency reference in the optical domain. Recently, such master oscillators have been developed in the 1.3 and 1.5-μm regions by frequency-locking semiconductor lasers to atomic and molecular absorption lines.^1-4 In particular, the technique employing the optogalvanic signals of the noble gas atoms is well-suited for use in lightwave systems since it is simple, compact, and offers many reference frequencies in the spectral regions of interest.^1-3 However, this technique needs a discharge lamp filled with a noble gas to obtain the optogalvanic signal corresponding to a specific atomic transition.

© 1992 Optical Society of America