Gain assisted nanocomposite multilayers with near zero permittivity modulus at visible frequencies

TL;DR

This paper demonstrates the fabrication of a layered nanocomposite with near-zero permittivity at visible frequencies by using gain media and effective medium theory, enabling potential applications in subwavelength optical steering.

Contribution

It introduces a novel layered nanocomposite with near-zero permittivity at visible wavelengths, achieved through gain-assisted design and optimized layer thicknesses.

Findings

Measured permittivity |ε| = 0.04 at 604 nm wavelength.

Achieved a 21.5% reduction in permittivity compared to non-pumped samples.

Confirmed the ability to synthesize media with very small permittivity modulus.

Abstract

We have fabricated a layered nano-composite by alternating metal and gain medium layers, the gain dielectric consisting of a polymer incorporating optically pumped dye molecules. Exploiting an improved version of the effective medium theory, we have chosen the layers thicknesses for achieving a very small value of the real part of the permittivity epsilon_\| (parallel to the layers plane) at a prescribed visible wavelength. From standard reflection-transmission experiments on the optically pumped sample we show that, at a visible wavelength, both the real and the imaginary parts of the permittivity epsilon_\ attain very small values and we measure | \epsilon_\| | = 0.04 at lambda = 604 nm, amounting to a 21.5-percent decrease of the minimum | \epsilon_\| | in the absence of optical pumping. Our investigation thus proves that a medium with a dielectric permittivity with very small modulus, a key condition which should provide efficient subwavelength optical steering, can be actually synthesized.