Portable ultra-broadband lasers could be key to next-generation sensors

August 10, 2015 by Amanda Morris, Northwestern University

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.

Capable of emitting broadband wavelengths on demand, the device is smaller than a penny and works at room temperature. It can also emit light at frequencies within +/- 30 percent of the laser central frequency, which has never before been demonstrated in a single-laser diode.

Supported by the National Science Foundation, US Department of Homeland Security, Naval Air Systems Command, and NASA, the research is described online in the August issue of Optics Express journal.

"When we started, we knew this technology had great potential," said Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science at Northwestern's McCormick School of Engineering. "It has always been my dream to have such broadband sources, but it took a lot of effort and experience to realize a truly useful device. We can access any frequency in the laser's range on demand at , which is ideal for sensing applications."

Explore further: Building a more versatile frequency comb

More information: Optics Express, www.osapublishing.org/oe/abstr … -21159&origin=search

Related Stories

Building a more versatile frequency comb

February 17, 2015

Frequency combs are the rulers of light. By counting a wavelength's many oscillations, they measure distance and time with extraordinary precision and speed.

Continuous terahertz sources demonstrated at room temperature

June 5, 2014

Imagine a technology that could allow us to see through opaque surfaces without exposure to harmful x-rays, that could give us the ability to detect harmful chemicals and bio-agents from a safe distance, and that could enable ...

Recommended for you

New insights into magnetic quantum effects in solids

January 23, 2019

Using a new computational method, an international collaboration has succeeded for the first time in systematically investigating magnetic quantum effects in the well-known 3-D pyrochlore Heisenberg model. The surprising ...

Rapid and continuous 3-D printing with light

January 22, 2019

Three-dimensional (3-D) printing, also known as additive manufacturing (AM), can transform a material layer by layer to build an object of interest. 3-D printing is not a new concept, since stereolithography printers have ...

Scientists discover new quantum spin liquid

January 22, 2019

An international research team led by the University of Liverpool and McMaster University has made a significant breakthrough in the search for new states of matter.

Researchers capture an image of negative capacitance in action

January 21, 2019

For the first time ever, an international team of researchers imaged the microscopic state of negative capacitance. This novel result provides researchers with fundamental, atomistic insight into the physics of negative capacitance, ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.