MIT Technology Review – Scientists have created the smallest ever laser capable of operating at room temperature. The device is less than one cubic micron–less than the wavelength of the light it emits. It is the first sub-wavelength laser that doesn’t require cryogenic cooling. Besides high-speed communications, sub-wavelength lasers could find applications in biomedical imaging and near-field optical microscopy
It should be possible to pack the microlasers close together without interference between devices. This paves the way for, among other things, faster optical communications devices that use sub-wavelength lasers in dense arrays.
They added a layer of silica to a microdisc laser, followed by a layer of aluminum around a laser cavity made of indium gallium arsenide phosphide. The outer metal layer acts like a shield, isolating the laser from other devices, and acting like a highly efficient heat sink. The silica layer prevents the metal from reducing the lasers’s overall efficiency.
In a paper published in the journal Nature Photonics, the UCSD group shows that its laser can produce emissions with a wavelength of 1.43 microns at room temperature. The group has received funding from the National Science Foundation as well as DARPA’s Nanoscale Architectures for Coherent Hyper-Optic Sources program.
In theory, the efficiency of the laser could be improved further by using other metals that have even more favorable optical properties, such as silver or gold, says Fainman.
A bigger challenge is finding a way for the lasers to be fully integrated into optoelectronic devices, by replacing the complex optical pump with an electrical one.
DARPA – Nanoscale Architecture for Coherent Hyper-Optic Sources (NACHOS)
Nanoscale Architecture for Coherent Hyper-Optic Sources (NACHOS)
Nanoscaled lasers will enable close integration of photonic and electronic devices needed in emerging high-speed processing-intense computing and communication platforms. In addition to reduced size, these lasers are expected to be power efficient and offer unprecedented modulation bandwidth. New capabilities, such as the ability to place large numbers of lasers on silicon chips, will be enabled by these devices.
The objective of the NACHOS program is to demonstrate sub-wavelength semiconductor lasers by combining media with reduced dimensionality and advanced feedback concepts. The specific program goal is to demonstrate injection lasers operating CW at room temperature with cavity dimensions smaller than the vacuum wavelength of light they generate, l < 1.5 mm