Proposal for a THz Spectroscopic Sensor Based on Semiconductor Quantum Cascade Lasers


There are a number of different types of laser based chemical sensors that can sense the absorption or refractive index of an analyte at a single or range of frequencies. Absorption spectroscopy is most common for gas sensing. Chemicals in condensed and liquid phases are sensed using evanescent-wave techniques that provide sensitive detection with small sample volumes. Most of the techniques currently available require either a broadly tunable laser source with single-mode operation and good beam quality, or a high-power broadband source in combination with a spectrometer.

To improve current techniques in spectroscopic sensing of the complex refractive index of an analyte, an inventor at Lehigh University has developed a concept of a broadband terahertz (THz) sensor based on arrays of single-mode quantum-cascade lasers (QCLs). The novel sensor is comprised of two distributed feedback QCLs that are arranged facing each other to form a sensing and reference unit. The QCLs are operated in a portable, electrically operated Stirling cryocooler. Beams of the sensing QCLs interact with an analyte that is placed outside the cryocooler in ambient conditions. Reflection of the emitted light from the sensing QCLs occurs due to the mismatch of the refractive index. The reflected wave couples back to the passive cavities surrounded by the analyte causing the resonant frequency of the sensing QCLs to shift. The corresponding frequency shift contains information about the THz response of the analyte.


Competitive Advantages

*Highly desirable sensing of large polar molecules irrespective of the molecular phase (solid or liquid) *In addition to quantum cascade sensors, the novel sensing method is applicable for any type of semiconductor laser, including semiconductor diode lasers operating at infrared frequencies *Highly selective solution that is also portable and cost effective *Analytes do not require preparation for sensing with conduction in ambient conditions

Lehigh Tech ID # 121814-01


Chemical sensors including the proposed THz spectroscopic sensor are essential for analyzing the chemical composition of samples in a variety of industries such as the biomedical and pharmaceutical industries. Growth in the biomedical sensor applications is fueling the overall global chemical sensors market. In the United State alone, the chemical sensor market is expected to increase at five percent annually to reach an overall market size of almost $2 billion in 2019.

Lehigh University is looking for a partner for further development and commercialization of this technology through a license and/or other collaboration opportunity. The inventor is available to collaborate with interested companies.

App Type Country Serial No. Patent No. File Date Issued Date Expire Date
Provisional [PR] United States 62/097904 12/30/2014   12/14/2015
For Information, Contact:
Alan Snyder
VP, Research & Grad Programs
Lehigh University
Sushil Kumar
Sudeep Khanal
Le Zhao