A middle infrared light source can detect greenhouse and other gases as well as molecules in a person’s breath. The compact system, which resembles a tiny suitcase, contains just two parts: a standard laser and a photonic chip measuring a few millimeters across.
The mid-infrared spectrum is useful for scientists because, at this wavelength range, light can detect particles that play an important role in the environment and in human health. Until now, however, infrared laser systems have proven difficult to transport because they involve complex, damage-prone hardware.
The new technology consists of a commercially available fiber laser combined with a micrometer waveguide chip to reliably generate light waves in the midinfraredspectrum.
A spectrometer was added to demonstrate the potential of the light source, successfully detecting the presence and concentration of acetylene, a colorless and highly flammable gas.
The system uses a compact and robust fiber laser that emits light in a specific wavelength range. The beam is directed through a waveguide, measuring one micrometer (0.001 mm) across and half a millimeter long that can alter the frequency of the light as it passes through. The system produces light in the mid-infrared spectrum, retaining 30 percent of the original signal strength. The researchers can even tune the wavelength of the light by adjusting the waveguide’s geometry. The technology eliminates the process of precisely aligning all the parts in a conventional laser system.