NRL demonstrates new non-mechanical laser steering technology

November 19, 2018, Naval Research Laboratory
To date, beam steering has typically relied on mechanical devices, such as gimbal-mounted mirrors or rotating Risley prisms, which have inherent issues, including large size, weight, and power (SWaP) requirements, slow scan rates, high repair and replacement costs, and short lifetimes before mechanical failure. Steerable electro-evanescent optical refractor (SEEOR) chips take laser light in the mid-wavelength infrared (MWIR) as an input and steers the beam at the output in two dimensions without the need for mechanical devices. SEEORs are meant to replace traditional mechanical beam steerers with much smaller, lighter, faster devices that use miniscule amounts of electrical power and have long lifetimes because they have no moving parts. Credit: Jason Myers/U.S. Naval Research Laboratory

Scientists at the U.S. Naval Research Laboratory have recently demonstrated a new nonmechanical chip-based beam steering technology that offers an alternative to costly, cumbersome and often unreliable and inefficient mechanical gimbal-style laser scanners.

The , known as a steerable electro-evanescent optical refractor, or SEEOR, takes in the mid-wavelength infrared (MWIR) as an input and steers the beam in two dimensions at the output without the need for —demonstrating improved steering capability and higher scan speed rates than conventional methods.

"Given the low size, weight and power consumption and continuous steering capability, this technology represents a promising path forward for MWIR beam-steering technologies," said Jesse Frantz, research physicist, NRL Optical Sciences Division. "Mapping in the MWIR spectral range demonstrates useful potential in a variety of applications, such as chemical sensing and monitoring emissions from waste sites, refineries, and other industrial facilities."

The SEEOR is based on an —a structure that confines light in a set of thin layers with a total thickness of less than a tenth that of a human hair. Laser light enters through one facet and moves into the core of the . Once in the waveguide, a portion of the light is located in a liquid crystal (LC) layer on top of the core. A voltage applied to the LC through a series of patterned electrodes changes the refractive index (in effect, the speed of light within the material), in portions of the waveguide, making the waveguide act as a variable prism. Careful design of the waveguides and electrodes allow this change to be translated to high speed and continuous steering in two dimensions.

SEEORs were originally developed to manipulate shortwave infrared (SWIR) light—the same part of the spectrum used for telecommunications—and have found applications in guidance systems for self-driving cars.

"Making a SEEOR that works in the MWIR was a major challenge," Frantz said. "Most common optical do not transmit MWIR light or are incompatible with the waveguide architecture, so developing these devices required a tour de force of materials engineering."

To accomplish this, the NRL researchers designed new waveguide structures and LCs that are transparent in the MWIR, new ways to pattern these materials, and new ways to induce alignment in the LCs without absorbing too much light. This development combined efforts across multiple NRL divisions including the Optical Sciences Division for MWIR materials, waveguide design and fabrication, and the Center for Bio/Molecular Science and Engineering for synthetic chemistry and liquid crystal technology.

The resulting SEEORs were able to steer MWIR through an angular range of 14°×0.6°. The researchers are now working on ways to increase this angular range and to extend the portion of the optical spectrum where SEEORs work even further. Complete details of this research can be found in the December 2018 edition of the Journal of the Optical Society of America.

Explore further: Triple bend structure splits light into two highly pure polarization components

More information: Jesse A. Frantz et al, Chip-based nonmechanical beam steerer in the midwave infrared, Journal of the Optical Society of America B (2018). DOI: 10.1364/JOSAB.35.000C29

Related Stories

Infrared imaging technique operates at high temperatures

January 23, 2015

From aerial surveillance to cancer detection, mid-wavelength infrared (MWIR) radiation has a wide range of applications. And as the uses for high-sensitivity, high-resolution imaging continue to expand, MWIR sources are becoming ...

Controlling light with light

January 10, 2014

A new approach to control light with light without the need for optical nonlinearity: Nanoparticle auto-oscillations in a subwavelength plasmonic V-groove waveguide induced by a control light can be used for the periodic ...

Recommended for you

Magic number colloidal clusters

December 14, 2018

Complexity in nature often results from self-assembly, and is considered particularly robust. Compact clusters of elemental particles can be shown to be of practical relevance, and are found in atomic nuclei, nanoparticles ...

Tangled magnetic fields power cosmic particle accelerators

December 13, 2018

Magnetic field lines tangled like spaghetti in a bowl might be behind the most powerful particle accelerators in the universe. That's the result of a new computational study by researchers from the Department of Energy's ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.