This self-sweeping
laser couples an optical field with the mechanical motion of a
high-contrast
grating (HCG) mirror. The HCG mirror is supported by mechanical springs
connected to
layers of semiconductor material. The red layer represents the laser’s gain
(for light
amplification), and the blue layers form the system’s second mirror.
The force of the
light causes the top mirror to vibrate at high speed. The vibration allows
the laser to
automatically change color as it scans. (Schematic by Weijian Yang)
(September 5, 2015) A
new approach that uses light to move mirrors could usher in a new generation of
laser technology for a wide range of applications, including remote sensing,
self-driving car navigation and 3D biomedical imaging.
A team of UC Berkeley engineers led by Connie Chang-Hasnain,
a professor of electrical engineering and computer sciences, used a novel
concept to automate the way a light source changes its wavelength as it sweeps
the surrounding landscape. They report their findings in the journal Scientific
Reports, published Thursday, Sept. 3.
The advance could have implications for imaging technology
using LIDAR, or light detection and ranging, and OCT, or optical coherence
tomography.
“Our paper describes a fast, self-sweeping laser that can
dramatically reduce the power consumption, size, weight and cost of LIDAR and
OCT devices on the market today,” said Chang-Hasnain, chair of the Nanoscale
Science and Engineering Graduate Group at UC Berkeley. “The advance could
shrink components that now take up the space of a shoebox down to something
compact and lightweight enough for smartphones or small UAVs [unmanned aerial
vehicles].”
LIDAR works by shining a beam of light at a target and
measuring the amount of time it takes to bounce back. Because the speed of light
is constant, this system can then be used to calculate distance. Self-driving
vehicles and remote sensing technology use LIDAR for navigation and the
creation of 3D maps.