Research
Terahertz Quantum Cascade Lasers (QCLs)
Terahertz radiation, loosely defined as having frequency from 0.1 to 10 THz, is a very attractive tool for several applications: gas sensing, medical imaging, security screening, astronomy etc. Unfortunately, there are currently no cheap, reliable and robust THz sources. QCLs are semiconductor devices based on intersubband (i.e. between different electronic states in the conduction band) radiative transitions. Such structures are not easy to design, nevertheless QCLs -- demonstrated in 1994 for the first time -- have already proven to be commercially viable devices in mid-infrared applications.
The main drawback of THz QCLs is their low operational temperature (~200K is the current record) and poor power performance in high temperatures. I am therefore mostly interested in pushing the temperature and power up, so that THz QCLs may be used in real-world applications. My current projects include:
- Investigating InGaAs/AlInAs/InP material system as an alternative to the standard GaAs/AlGaAs.
- Looking at the performance from the quantum design point of view, i.e. trying to design a better band structure for a THz QCL.
- Searching for ways to significantly reduce waveguide losses, which contribute greatly to the performance.
