Experimental realization of optical lumped nanocircuits at infrared wavelengths

Abstract

The integration of radiofrequency electronic methodologies on micro- as well as nanoscale platforms is crucial for information processing and data-storage technologies. In electronics, radiofrequency signals are controlled and manipulated by 'lumped' circuit elements, such as resistors, inductors and capacitors. In earlier work, we theoretically proposed that optical nanostructures, when properly designed and judiciously arranged, could behave as nanoscale lumped circuit elements--but at optical frequencies. Here, for the first time we experimentally demonstrate a two-dimensional optical nanocircuit at mid-infrared wavelengths. With the guidance of circuit theory, we design and fabricate arrays of Si3N4 nanorods with specific deep subwavelength cross-sections, quantitatively evaluate their equivalent impedance as lumped circuit elements in the mid-infrared regime, and by Fourier transform infrared spectroscopy show that these nanostructures can indeed function as two-dimensional optical lumped circuit elements. We further show that the connections among nanocircuit elements, in particular whether they are in series or in parallel combination, can be controlled by the polarization of impinging optical signals, realizing the notion of 'stereo-circuitry' in metatronics-metamaterials-inspired optical circuitry.

Modular assembly of optical nanocircuits

“…In summary, we have demonstrated the design and operation of several 'stand-alone' optical nanocircuits, without the geometry and symmetry constraints imposed in previous experiments on nanocircuits 4,18 . The modularization of the optical response by means of lumped optical elements has allowed us to design photonic nanocircuits of increasing complexity by connecting our basic building blocks, nanoinductors and nanocapacitors, in different topologies.…”

“…Small colloidal metallic and dielectric nanoparticles (NPs), readily synthesized with conventional chemical processes, are the ideal platforms to translate these concepts to optical frequencies. Using optical nanocircuit concepts [1][2][3][4] , the intrinsic optical impedance of NPs may be controlled by their geometry and material composition. This impedance is defined as the ratio of the local potential difference V ¼ |E|l and the flux of displacement current I d ¼ À io|E|S through the NP [1][2][3][4] , where E is the local electric field vector, l is the NP length along the electric field, o is the frequency of operation, e is the NP dielectric constant and S is its transverse cross-section.…”

“…Metatronic concepts have provided a useful theoretical framework connecting plasmonics, metamaterials and nanophotonics with conventional electronics [2][3][4][5] . These ideas have guided the efficient design of metasurfaces 6,7 and the modelling of a variety of composite nanostructures, including plasmonic NP clusters [8][9][10] , NP rings exhibiting strong optical magnetism 11 and microcavity lasers 12 .…”

“…These ideas have guided the efficient design of metasurfaces 6,7 and the modelling of a variety of composite nanostructures, including plasmonic NP clusters [8][9][10] , NP rings exhibiting strong optical magnetism 11 and microcavity lasers 12 . However, the direct application of these concepts to photonic circuits has so far been limited to modelling and tuning optical nanoantennas [13][14][15][16][17][18][19] , and to realizing a ladder network of two-dimensional (2D) nanoinductors and nanocapacitors in the form of a subwavelength grating at mid-infrared frequencies 4 . These earlier experiments have demonstrated nanocircuits with limited complexity and specific symmetry constraints.…”

Manipulation of Asymmetric Transmission in Planar Chiral Nanostructures by Anisotropic Loss

“…By treating all the resonators as a whole metafi lm and combining it with transmission line theory, circuit models with lumped element parameters have been successfully used to analyze metamaterials working at terahertz and infrared regions. [ 27,28 ] Here, we also use an OLE model to describe the infrared light wave propagation through the PCSs.…”