As lasers are now used for a range of applications, such as communication devices, optical recording technologies and laser printers, scientists have now streamlined the semiconductor laser opening the door for many more uses.
Harvard University applied scientists, working in collaboration with researchers from Hamamatsu Photonics, Japan, have demonstrated highly directional semiconductor lasers with a much smaller beam variance. This innovation now allows for a broad range of applications in photonics (semiconductor induced lasers) and communications.
"Our innovation is applicable to edge-emitting as well as surface-emitting semiconductor lasers operating at any wavelength - all the way from visible to telecom ones and beyond," said Harvard University graduate student, Federico Capasso. "It is an important first step towards beam engineering of lasers with unprecedented flexibility, tailored for specific applications. In the future, we envision being able to achieve total control of the spatial emission pattern of semiconductor lasers such as a fully collimated beam, small divergence beams in multiple directions, and beams that can be steered over a wide angle."
Previously, semiconductor lasers, the most commonly used among all lasers, suffered from a vast beam divergence – due to diffraction, when light bends or spreads around obstacles.
To get around this problem, the researchers sculpted a metallic structure directly on the facet of a quantum cascade laser. This reduced the divergence angle of the beam. The team believe that this laser could be used for long range chemical sensing in the atmosphere, such as environmental monitoring.
"Such an advance could also lead to a wide range of applications at the shorter wavelengths used for optical communications. A very narrow angular spread of the laser beam can greatly reduce the complexity and cost of optical systems by eliminating the need for the lenses to couple light into optical fibres and waveguides," said Head of Hamamatsu Photonics, Dr. Hirofumi Kan.
The findings were published online in the 28 July issue of Nature Photonics.
Working with lasers
Meet a PhD student working with laser spectroscopy to study the dynamics of gas phase reactions.
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Date Published: July 28, 2008
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