TABLE OF CONTENTS The fundamentals of the semiconductor laser are presented in this chapter, which provide the foundation for understanding the time-domain laser models in Chapters 14 and 15. The basic concepts here also supplement the additional theory provided in Chapter 16 that is required to model the tapered structure semiconductor laser. In addition, sufficient background in ultrashort pulse generation schemes using laser diodes will be given, with emphasis on active mode-locking, the technique used in the novel multisegment mode-locked laser design in Chapter 17.
The first laser, based on the ruby rod, was demonstrated by Maiman in 1960 [ [1]]. The dawn of optoelectronics began in 1962 when gallium arsenide (GaAs) and gallium arsenide phosphide (GaAsP) semiconductor lasers were independently demonstrated by four groups led by Hall, Nathan, Rediker, and Holonyak [ [2]]. The semiconductor laser developed slowly from a pulse-operated simple p.n. homojunction to continuously operated (300 K) double heterostructure (DH) in 1970 [ [3]]. Research and development of the semiconductor laser, together with the introduction of low-loss optical fibres, anticipated as early as 1966 by Kao and Hockham [ [4]], have opened up the door for optical communications.
The semiconductor laser diode was chosen to play a key role in optical communications because of its compact-size, suitable wavelength range, and high reliability. The direct energy transition of the III-V semiconductor compounds means that we can achieve high quantum efficiency in the conversion of electron-hole pairs to photons, providing a clear advantage over indirectly...
