Quantum cascade lasers (QCLs) and associated devices are compact, room temperature (RT) sources capable of producing electromagnetic radiation in the midinfrared and terahertz (THz) spectral regions. This article will discuss the basic operation of QCLs, the evolution of performance in the past several years, and an overview of material growth and characterization, and QCL device fabrication. This article will also review recent research on mid-infrared QCLs that has resulted in record high wallplug efficiency (WPE), high continuous wave (CW) output power, single mode operation, wide wavelength tunability, and RT THz generation.

Chapter Contents:

• 6.1 Introduction
• 6.2 Summary of quantum cascade laser development
• 6.3 QCL Basics
• 6.4 Rate equations and figures of merit
• 6.5 The QCL waveguide
• 6.6 Choosing a material system
• 6.7 Material growth and characterization
• 6.8 Laser fabrication
• 6.9 Development of high-efficiency lasers
• 6.10 Developing short-wavelength, high-power QCLs
• 6.11 Power scaling of quantum cascade lasers
• 6.12 Spectral and spatial filtering of quantum cascade lasers
• 6.13 Monolithic wavelength tuning with quantum cascade lasers
• 6.14 Room temperature THz emission based on difference frequency generation in mid-IR QCLs
• 6.15 Conclusion
• References

Inspec keywords: optical materials; terahertz wave generation; quantum cascade lasers; laser modes; laser tuning; laser beams; optical fabrication

Other keywords: single mode operation; temperature 293 K to 298 K; midinfrared spectral regions; midinfrared QCL; associated devices; material growth; basic operation; wavelength tunability; continuous wave output power; electromagnetic radiation; quantum cascade lasers; terahertz spectral regions; QCL device fabrication; RT THz generation; room temperature sources; wallplug efficiency

Subjects: Laser beam modulation, pulsing and switching; mode locking and tuning; Semiconductor lasers; Lasing action in semiconductors; Design of specific laser systems; Laser beam modulation, pulsing and switching; mode locking and tuning; Optical materials; Laser beam characteristics and interactions; Other optical materials; Optical fabrication, surface grinding