Negative-index layers in multilayer optical coatings lead to novel properties

May 1, 2014
A group of researchers has taken a look at the use of double-negative-refractive-index (DNRI) metamaterials from the point of view of optical multilayer thin-film coating and filter designers.

A group of researchers has taken a look at the use of double-negative-refractive-index (DNRI) metamaterials from the point of view of optical multilayer thin-film coating and filter designers. What they have discovered is that the replacement of, for example, the high-index layers in a multilayer thin-film optical coating with negative-index layers, drastically changes the optical properties, even allowing the existence of a type of multilayer Fabry-Perot (FP) cavity with a linear dependence of the overall round-trip phase in the cavity that is equal or very close to zero, a so-called "white" multilayer FP cavity. (The multilayer FP cavity, consisting of two multilayer reflectors sandwiching a thin-film center, is a standard approach to designing multilayer optical filters.)

The researchers modeled negative refractive index in a simple way, simulating a negative-index material of positive thickness in a thin-film design program by substituting a replacement material having the same magnitude of thickness and index, but with negative rather than positive values. In three chosen designs (the structural terminology M3 2L M3, for example, signifies three multilayer stacks, a double low-index central layer, and then three more multilayer stacks) with different negative-index values, the wavelength dependence of the coating was tuned from low to lower to zero (blue, red, and black, respectively). Coatings containing negative-index layers could someday greatly broaden the capabilities of multilayer optical coatings, said the researchers.

Contact Michel Lequime at[email protected].

Sponsored Recommendations

Ask the Expert: Building Better Laser Micromachining Systems

Dec. 8, 2023
Dr. Cliff Jolliffe, Head of Strategic Marketing, Industrial Automation, Physik Instrumente (PI), fields questions about integrating controls for different motion systems and lasers...

Video: December 8, 2023 Photonics Hot List

Dec. 8, 2023
In this episode, we cover a microscopy method that hits uncharted cell territory, drone-based imaging for solar farm inspection, soliton microcombs that boost conversion efficiency...

China’s industrial laser market shows steady growth in turbulent times

Dec. 8, 2023
This in-depth market update focuses on trends in laser processing and industrial lasers while touching on what to expect in the ultrafast laser, fiber laser, LiDAR, and handheld...

What does it take to land venture capital for photonics-driven startups?

Dec. 7, 2023
Capital to grow a startup company can come from many sources: contract and non-recurring engineering (NRE) funding, angels and friends, customer upfront payments, and venture ...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!