Abstract

The frequency stabilization of a semiconductor laser under direct modulation is necessary for optical communication. Generally speaking, the frequency stabilization of a diode laser under direct frequency shift keying (FSK) is difficult because of its inevitable sideband spectra.¹ However, we devised the peak-hold method,^2–4 and obtained the better stability than in the traditional method under direct FSK. We report about the effect of a duty ratio of rectangular wave modulation to the accuracy of a stabilized frequency and its improvement in the peak-hold method. We also report about the effect of the frequency chirping under direct FSK to the frequency stability and accuracy.

© 1991 Optical Society of America