TABLE OF CONTENTS Although today microwave and optical engineering appear to be separate disciplines, there has been a tradition of interchange of ideas between them. In fact, many traditional microwave concepts have been adapted to yield optical counterparts. The laser, as an optical device that plays a key role in optoelectronics and fibre-optic communications, grew from the work of its microwave predecessor, the maser (microwave amplification by stimulated emission of radiation) [ [1]]. The operating principle behind the laser is very similar to that of the microwave oscillator. In a semiconductor laser, the required feedback may either be provided by the cleaved facets of Fabry-Perot (FP) lasers or by a periodic grating in distributed feedback (DFB) lasers. Certain optical techniques, such as injection locking of lasers by external light [ [2]], are ideas borrowed from the phenomenon of injection locking of microwave oscillators by an external electronic signal [ [3]]. The close relationship between optical and microwave principles suggests that it may be advantageous to apply microwave circuit techniques in modelling of semiconductor lasers.
Engineers work best when using tools they are familiar with. In particular, electrical and electronic engineers are familiar with well-established electrical circuit models as tools to aid themselves in the understanding and prediction of behaviour of electrical machines or electronic devices. Since the early days of radio frequency (RF) and microwave engineering, microwave circuit theory has allowed us to explore fundamental properties of electromagnetic waves by giving us an intuitive understanding of electromagnetic waves...
