Portable lasers key to next-generation sensors

Scientists at Northwestern University have developed a custom-made, 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.

"We can access any frequency in the laser's range on demand at room temperature, which is ideal for sensing applications," said lead researcher Professor Manijeh Razeghi.

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.

Nearly all chemicals, including explosives, industrials 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, the new laser device can make detecting chemicals easier.

The findings were published online in the journal Optics Express journal.