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

Advancing Neuroscience Using High-Precision 3D Printing

March 7, 2025
Learn how Cold Spring Harbor Laboratory Used High-Precision 3D Printing to Advance Neuroscience Research using 3D Printed Optical Drives.

From Prototyping to Production: How High-Precision 3D Printing is Reinventing Electronics Manufacturing

March 7, 2025
Learn how micro 3D printing is enabling miniaturization. As products get smaller the challenge to manufacture small parts increases.

Sputtered Thin-film Coatings

Feb. 27, 2025
Optical thin-film coatings can be deposited by a variety of methods. Learn about 2 traditional methods and a deposition process called sputtering.

What are Notch Filters?

Feb. 27, 2025
Notch filters are ideal for applications that require nearly complete rejection of a laser line while passing as much non-laser light as possible.

Voice your opinion!

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