Precise LIDAR Devices: Metasurface for Large-Angle Beam Steering
- Large steering angle range
- Operation beyond infrared possible
- Quasi-continuous spatial frequency patterns
- Design easily adoptable for other wavelengths
- Beam steering
Metasurfaces are a promising class of optical components with a growing field of applications. However, beam steering with a metasurface remains challenging and limits the applicability for devices like LIDAR systems. State-of the art metasurfaces cannot cover a large range of steering angles and are typically limited to IR light with the requirement of specifically chosen wavelengths and thus limited flexibility.
A novel electrically-controllable dynamic metasurface has been developed to overcome the aforementioned shortcomings that allows the use in large angle beam steering applications like LIDAR. It is based on the amplitude modulation with adjustable spatial patterns.
A metasurface according to the invention (cf. fig. 1) comprises multiple rows of gold nanorods (AuNRs), which are grouped in pairs on top of ITO bottom electrodes. Of the two sub-rows, one is coated with an active material that changes its refractive index upon changes of the potential V, while the other remains constant. Therefore, the different potentials Vi control the reflected amplitudes of the rows i and the surface can thus be used as an optical grating with adjustable spatial frequency. Different spatial frequencies correspond to different diffraction angles and the maximum steering angle results from the highest periodicity. Hence, a metasurface corresponding to the invention can achieve remarkably wide angles due to its high resolution.
If used together with a pulsed laser, the steered light beam can be used in a LIDAR system (cf. fig. 3). Reflected light can be detected by a photo-detector and from the propagation time, an objects distance can be calculated. As a light scanning unit, the incident time-triggered pulses are steered across a range of angles without the need of mechanically moving parts.
PCT (Application filed), EP
- Ref.-No.: 1201-6235-BC (714.2 KiB)
Dr. Bernd Ctortecka, M. Phil.
Phone: +49 89 / 29 09 19-20