NRL Improves Optical Efficiency in Nanophotonic Devices


Reading time ( words)

A team of physicists, headed by the U.S. Naval Research Laboratory (NRL), have demonstrated the means to improve the optical loss characteristics and transmission efficiency of hexagonal boron nitride devices, enabling very small lasers and nanoscale optics.

“The applications for this research are considerably broad,” said Dr. Alexander J. Giles, research physicist, NRL Electronics Science and Technology Division. “By confining light to very small dimensions, nanophotonic devices have direct applications for use in ultra-high resolution microscopes, solar energy harvesting, optical computing and targeted medical therapies.”

Hexagonal boron nitride (hBN) forms an atomically thin lattice consisting of boron and nitrogen atoms. This material has recently been demonstrated as an exciting optical material for infrared nanophotonics and is considered an ‘ideal substrate’ for two-dimensional materials.

While previous work demonstrated that natural hBN supports deeply sub-diffractional hyperbolic phonon polaritons desired for applications, such as, sub-diffractional optical imaging (so-called ‘hyperlensing’), energy conversion, chemical sensing, and quantum nanophotonics, limited transmission efficiencies continue to persist.

"We have demonstrated that the inherent efficiency limitations of nanophotonics can be overcome through the careful engineering of isotopes in polar semiconductors and dielectric materials,” Giles said.

Naturally occurring boron is comprised of two isotopes, boron-10 and boron-11, lending a 10 percent difference in atomic masses. This difference results in substantial losses due to phonon scattering, limiting the potential applications of this material. The research team at NRL has engineered greater than 99 percent isotopically pure samples of hBN, meaning they consist almost entirely of either boron-10 or boron-11 isotopes.

This approach results in a dramatic reduction in optical losses, resulting in optical modes that travel up to three times farther and persist for up to three times longer than natural hBN. These long-lived vibrational modes not only enable immediate advances specific to hBN — near field optics and chemical sensing — but also provide a strategic approach for other materials systems to exploit and build upon.

“Controlling and manipulating light at nanoscale, sub-diffractional dimensions is notoriously difficult and inefficient,” said Giles. “Our work represents a new path forward for the next generation of materials and devices.”

Contributors to this research include scientists from the University of California San Diego, Kansas State University, Oak Ridge National Laboratory, Columbia University, and Vanderbilt University. Full details of this research entitled “Ultralow-loss polaritons in isotopically pure boron nitride,” can be found in the December 11, 2017 edition of Nature Materials (doi:10.1038/nmat5047).

Share


Suggested Items

Beyond Scaling: An Electronics Resurgence Initiative

06/05/2017 | DARPA
The Department of Defense’s proposed FY 2018 budget includes a $75 million allocation for DARPA in support of a new, public-private “electronics resurgence” initiative. The initiative seeks to undergird a new era of electronics in which advances in performance will be catalyzed not just by continued component miniaturization but also by radically new microsystem materials, designs, and architectures.

DARPA Researchers Develop Novel Method for Room-Temperature Atomic Layer Deposition

09/01/2016 | DARPA
DARPA-supported researchers have developed a new approach for synthesizing ultrathin materials at room temperature—a breakthrough over industrial approaches that have demanded temperatures of 800 degrees Celsius or more. T

Finessing Miniaturized Magnetics into the Microelectronics Mix

06/20/2016 | DARPA
A newly-announced DARPA program is betting that unprecedented on-chip integration of workhorse electronic components, such as transistors and capacitors, with less-familiar magnetic components with names like circulators and isolators, will open an expansive pathway to more capable electromagnetic systems.



Copyright © 2018 I-Connect007. All rights reserved.