QCL Sensors

Quantum Cascade Laser Sensors


The laboratory is exploring the application of quantum cascade lasers (QCL) in a number of domains. The QCLs are useful as they allow us to access the stronger vibrational bands in the mid-IR. It is possible to design sensors which are free from interference of other species and can detect trace quantities. The figure below shows spectrum of a few gases and how the use of QCLs provides opportunities for working with strong absorption strengths:
QCL Spectrum.png

A variety of projects are being pursued that use QCLs:
  • An ultrafast (2 MHz) temperature sensor using intrapulse absorption of H2O
  • Ethylene detection using pulsed cavity ringdown spectroscopy at 100 kHz
  • Measurements of H2O2, C2H2, and CH4 using an external-cavity QCL
  • Sensitive detection of CO and CO2 in the fundamental vibrational bands
  • Breath sensors using wavelengt​h modulation spectroscopy and multipass cell
Exhaled human breath contains a larger number of chemical species. These chemicals are usually present in the breath of a healthy person in small quantities. However, increased concentration of specific species can be directly linked to the functioning of particular organ. The measurement of such species can, therefore, be used as biomarkers for specific diseases or abnormal conditions. Our group is using quantum cascade lasers to develop new sensors that will be used to detect select gases in human breath. Successful demonstration of this strategy can lead to portable sensors for monitoring diabetes, asthma​ attacks, kidney/liver functions and smoking levels.