Frequency tuning of terahertz quantum-cascade lasers by optical excitation

摘要

The ability to tune the frequency is an important requirement for a local oscillator (LO) in a heterodyne spectrometer. When employed as LO, terahertz (THz) quantum-cascade lasers (QCLs) are usually tuned by changing their driving current or temperature [1]. This yields a frequency tunability of a few GHz. In addition to the small frequency coverage, the output power of the QCL does not remain constant using this method.