9.3 Diode lasers in the near infra-red spectral range

Abstract

Electrically pumped diode lasers emitting in the Near Infra-Red (NIR) spectral range (785-1400 nm) have been under intensive development for over 40 years, and are in wide commercial use in a range of applications. In an updated version of [08Wen1], we review here the semiconductor materials used to construct these devices and give an overview of peak performance published in recent articles. NIR diode lasers can be made using binary, ternary, quaternary, and quinternary compound alloys in the III-V material system. Materials with direct bandgaps of the required NIR emission wavelength can be currently grown with high quality typically on either InP or GaAs wafer substrates (other substrates such as InGaAs are also possible). Quantum-size effects can be used to adjust the emission wavelength through the use of nm-scale quantum well, wire, or dot structures. Such nm-scale structures allow in addition the use of moderate levels of crystal strain, which enables further modification in the emission wavelength. Figure 9.3.1 gives an overview of the 300 K bandgap of compound materials from the AlInGaAsSb material system as a function of lattice constant, as used in the majority of NIR diode lasers.