
diode by injection locking, turning a multimode laser into a single-mode laser with
much lower mode partition noise. Lang [7] published the first theory paper on
injection locking of semiconductor lasers, which established the theoretical frame-
work and became the foundation of various subsequent theoretical predictions and
studies. Over the next two decades, significant progress was made with numerical
simulations and experimental demonstrations of chirp reduction [8–10], modulation
bandwidth enhancement [11–14], and broadband noise reduction [11, 15, 16].
In this chapter, the physical origin and theoretical and experimental results of
injection-l ...