An electro-tunable Fabry–Perot interferometer based on dual mirror-on-mirror nanoplasmonic metamaterials

Abstract

Mirror-on-mirror nanoplasmonic metamaterials, formed on the basis of voltage-controlled reversible self-assembly of sub-wavelength-sized metallic nanoparticles (NPs) on thin metallic film electrodes, are promising candidates for novel electro-tunable optical devices. Here, we present a new design of electro-tunable Fabry–Perot interferometers (FPIs) in which two parallel mirrors – each composed of a monolayer of NPs self-assembled on a thin metallic electrode – form an optical cavity, which is filled with an aqueous solution. The reflectivity of the cavity mirrors can be electrically adjusted, simultaneously or separately, via a small variation of the electrode potentials, which would alter the inter-NP separation in the monolayers. To investigate optical transmittance from the proposed FPI device, we develop a nine-layer-stack theoretical model, based on our effective medium theory and multi-layer Fresnel reflection scheme, which produces excellent match when verified against full-wave simulations. We show that strong plasmonic coupling among silver NPs forming a monolayer on a thin silver-film substrate makes reflectivity of each cavity mirror highly sensitive to the inter-NP separation. Such a design allows the continuous tuning of the multiple narrow and intense transmission peaks emerging from an FPI cavity via electro-tuning the inter-NP separation in situ – reaping the benefits from both inexpensive bottom-up fabrication and energy-efficient tuning.

Disordered-nanoparticle–based etalon for ultrafast humidity-responsive colorimetric sensors and anti-counterfeiting displays

“…The underlying physics closely relate to MNPs on top that act like a highly absorbing dielectric layer (34). Moreover, the randomly dispersed (disordered) subwavelength MNPs are known to have material-independent broadband absorption (28)(29)(30)(31)37), thus enabling sharper reflection peaks and more vivid colors than metal-insulator-metal cavities (34). For the detailed analysis of MNHM etalon, we calculated the effective refractive index of AgNPs-SCN slab (text S2) and derived the overall reflection coefficient of the etalon based on scattering matrix models (text S3).…”

Nanoparticle meta-grid for enhanced light extraction from light-emitting devices

“…Fabry–Perot effects can be seen between any two parallel reflective surfaces, however, the higher is the reflectivity of the reflective surfaces the better is the quality factor of the resonance peak. We have shown Fabry–Perot cavity effects in our previous works 30 , 31 between two parallel NP-layers, with moderate or high reflectivity. In this work, the chip/encapsulant interface and the NP meta-grid act as the two reflective surfaces forming the cavity in between them, where encapsulating material acts as the cavity medium.…”

“…Source and destination ports were deployed at the emitter and the detector ends, respectively. Using the frequency domain solver over the desired spectral range, the transmittance spectrum was obtained from S 21 coefficient of the numerically calculated S parameters 31 .…”

Electrochemically driven dynamic plasmonics

“…The voltage control can guide the reversibility between a highly reflective "mirror" to a transmissive "window." 67 Furthermore, the nanoparticle assembly/disassembly enabled dynamic plasmonics can be extended to new designs/structures, including metal nanocuboids, 68 Fabry-Perot interferometers, 3D superstructures, 69,70 and different substrates (the interphase of liquid and dielectric/metal film substrates). 71,72 For theoretical understanding, refer to Refs.…”