Abstract

In earlier work¹ the role of gain nonlinearities in effecting self-locked FM oscillation in semiconductor lasers was established. In FM operation, the longitudinal modes of the laser become equally spaced in frequency and the cavity modes form a single frequency-modulated (FM) optical wave: the so-called FM supermode. The requisite gain nonlinearities and lasing field intensities have been shown to be consistent with the experimental observations of Tiemeijer et al.² To demonstrate the occurrence of intrinsic FM locking in semiconductor lasers, it is sufficient to utilize a three-mode laser model, but to establish the depth of FM modulation in the self-locked state it is necessary to extend the model of Ref. 1 to take more than three modes into account. In the present paper we describe calculations made using a multimode model of the FM-locking dynamics of laser diodes and specifically report results obtained for a seven-mode model. It is found that an FM modulation index of ~1.8 is obtained for parameters typical of long- wavelength laser diodes.

© 1991 Optical Society of America