NU 2015-195

Inventors

Manijeh Razeghi*

Short Description

A rapid tunable QCL laser with no moving parts for spectroscopy  

Abstract

Many chemicals have signature absorption spectra in the mid-infrared (IR) wavelength range. For chemical-sensing based applications, including medical diagnostics, explosive detection and industrial process monitoring, a portable laser emitting in a wide wavelength range is highly desired. Among semiconductor laser sources, quantum cascade lasers (QCLs) have increasingly exhibited strength in the mid-IR wavelength range, due to the developments in power, wall-plug efficiency, and single mode operation. In particular, the broadband QCL has demonstrated a gain bandwidth of 5.9-10.9-μm, highlighting its incredible potential for mid-IR spectroscopy. However, fine tuning the wavelength of lasers has often relied on external cavity feedback or exhibited a limited monolithic tuning range. Northwestern researchers have developed a widely tunable QCL source over the 6.2 to 9.1 μm wavelength range. This compact tunable laser system was built to drive individual lasers within the array and produce any desired wavelength within the available spectral range. For example, a rapid, broadband spectral measurement (520 cm−1) of methane using the tunable laser source shows excellent consistency with a measurement made using a standard low-speed infrared spectrometer. This monolithic, widely tunable laser technology is portable with no moving parts and opens new opportunities for mid-IR spectroscopy and chemical sensing.

Applications

• Chemical sensing system
• Medical Diagnostics
• Explosive Detections
• Industrial Process Monitoring

Advantages

• Single chip laser array
• Beam combiner provides single aperture output
• Very robust with no moving parts in the laser or laser beam path
• Rapid turning rate
• Very fine control of the laser output wavelength
• Compact, stand-alone, and portable

Publications

Zhou W, Bandyopadhyay N, Wu D, McClintock R, Razeghi M (2016) Monolithically, widely tunable quantum cascade lasers based on a heterogeneous active region design. Scientific Reports. 6: 25213.

IP Status

A provisional patent application was filed.