Abstract

GaInAsP/InP DH lasers have been studied intensively as the most promising light source for ultra low loss optical fiber communications [1,2]. In 1.3µm wavelength region, where material dispersion problem doesn't exist, many kinds of excellent laser diodes were realized which can be applied to practical use. However, most of conventional structure lasers can't be applied to 1.5-1.6µm wavelength optical fiber communications due to spectrum broadening under high frequency modulation which limits the transmission bandwidth of optical fiber [3,4]. Thus pure spectral property of laser diode even in high frequency modulation is essential for very long distance optical fiber communication system using 1.5-1.6µm wavelength region where transmission loss of optical fiber is almost half of that in 1.3µm wavelength region. Distributed Bragg Reflector (DBR) and Distributed Feedback (DFB) lasers are only promising devices for such a long distance communication or further efficient communication methods, i.e. wavelength division multiplexing and heterodyn detection [5,6]. For these practical use, low threshold current operation of those lasers is the most important in order to get room temperature CW operation.

© 1982 Optical Society of America