Chapter 6 - Ultrafast High Power and Stabilized Semiconductor Diode Lasers—Physics, Techniques, and Applications in Coherent Signal Processing

Abstract

Abstract Compact, electrically efficient sources of ultrashort, high repetition rate laser pulses are becoming critical for a broad range of applications in optical communications and signal processing. This article reviews the basic principles and techniques for generating ultrashort, high peak power optical pulses from electrically pumped semiconductor gain media. The techniques described show how to circumvent the physical limitations that are normally associated with the production of ultrashort pulses using semiconductor gain media. Insight is gained that suggests the use of specific laser cavity designs to achieve the desired output pulse train characteristics, including femtosecond duration pulses, high peak intensity pulses, and pulse trains with ultralow intensity and timing noise. Furthermore, we highlight the most recent applications involving optical frequency combs that are generated using stabilized mode-locked lasers. We show that the periodic nature of the output axial mode spectrum of a mode-locked laser serves as a basis for performing a variety of parallel optical signal processing functions, such as arbitrary waveform generation, waveform measurement, and matched filtering, yielding processing rates at the full bandwidth of the laser (several terahertz) but requiring electronics with bandwidths on the order of the laser’s pulse repetition rate (a few gigahertz).