One of the major uses of laser technology is in sensor devices. Typically, a beam of laser light (usually of a single wavelength) is passed through a medium such as air and various properties can be measured by spectroscopic techniques such as absorption, emission, or scattering. This type of sensor can be used for monitoring weather, pollution, greenhouse gases, toxic fumes and the like. However, current laser sensors work with one beam or wavelength at a time. New research has created a multibeam (or wavelength) laser device with enormous potential.
An international team of applied scientists from Harvard, Hamamatsu Photonics, and ETH Zürich have demonstrated compact, multibeam, and multi-wavelength lasers emitting in the invisible part of the light spectrum (infrared). By contrast, typical lasers emit a single light beam of a well-defined wavelength. The innovative multibeam lasers have potential use in applications related to remote chemical sensing pollution monitoring, optical wireless, and interferometry.
“We have demonstrated devices that can create highly directional laser beams pointing in different directions either at the same or at different wavelengths,” says Capasso [Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, both at the Harvard School of Engineering and Applied Sciences]. “This could have major implications for parallel high-throughput monitoring of multiple chemicals in the atmosphere or on the ground and be used, for example, for studying hazardous trace gases and aerosols, monitoring greenhouse gases, detecting chemical agents on the battlefield, and mapping biomass levels in forests.”
The more versatile laser is a descendant of the quantum cascade laser (QCL), invented and first demonstrated by Capasso, Faist, and their collaborators at Bell Labs in 1994. Commercially available QCLs, made by stacking ultra-thin atomic layers of semiconductor materials on top of one another, can be custom designed to emit a well -defined infrared wavelength for a specific application or be made to emit simultaneously multiple wavelengths. To achieve multiple beams, the researchers patterned the laser facet with metallic structures that behave as highly directional antennas and then beam the light in different directions.
[Source: Nanotechnology Today]
The next steps with this new type of laser device will be further testing, experimenting with applications, and preparation for production manufacturing.