August 10, 2015

Portable Ultra-Broadband Lasers Could be Key to Next-Generation Sensors

Manijeh Razeghi

The compact laser could sense chemicals for a variety of applications

(August 10, 2015)  The invisible chemicals around and within us can tell many complicated stories. By sensing them, security agents can uncover explosive threats. By monitoring them in our breath, doctors can diagnose serious illnesses. And by detecting them on distant planets, astronomers may find signs of life.

These chemicals sometimes reveal their secrets when probed with mid-infrared wavelength lasers. Nearly all chemicals, including explosives, industrial, and pollutants, strongly absorb light in the mid-infrared wavelength region, which is often called the “fingerprint region” for chemicals.

But lasers that work within this range have limitations. Larger, optically pumped lasers are too complex to use out in the field, and compact, lightweight diode laser sources have a limited spectral range. Now Manijeh Razeghi and her team at Northwestern University’s Center for Quantum Devices have used quantum mechanical design, optical engineering, and materials development to create a custom-tailored, compact laser diode by integrating multiple wavelength emitters into a single device.

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