Abstract

For such applications as coherent communications, narrow-linewidth semiconductor lasers are required. Although at low powers the laser linewidth narrows with increasing power, at high powers the linewidth saturates and often rebroadens.¹ The presence of side modes can affect the laser linewidth because the side modes are coupled to the main mode not only through the population inversion² but also by other mechanisms as expressed by the nonlinear gain.³ Such cross saturation can significantly enhance both the laser intensity noise as well as the frequency fluctuations

© 1991 Optical Society of America