Tailoring the lineshapes of coupled plasmonic systems based on a theory derived from first principles

Abstract

Coupled photonic systems exhibit intriguing optical responses attracting intensive attention, but available theoretical tools either cannot reveal the underlying physics or are empirical in nature. Here, we derive a rigorous theoretical framework from first principles (i.e., Maxwell’s equations), with all parameters directly computable via wave function integrations, to study coupled photonic systems containing multiple resonators. Benchmark calculations against Mie theory reveal the physical meanings of the parameters defined in our theory and their mutual relations. After testing our theory numerically and experimentally on a realistic plasmonic system, we show how to utilize it to freely tailor the lineshape of a coupled system, involving two plasmonic resonators exhibiting arbitrary radiative losses, particularly how to create a completely “dark” mode with vanishing radiative loss (e.g., a bound state in continuum). All theoretical predictions are quantitatively verified by our experiments at near-infrared frequencies. Our results not only help understand the profound physics in such coupled photonic systems, but also offer a powerful tool for fast designing functional devices to meet diversified application requests.

Inverse Design of Metasurfaces Based on Coupled-Mode Theory and Adjoint Optimization

“…The expression of evanescent-wave coupling Ω mm ′ is analytically available for resonances with isotropic, dipolar, or multipole radiation profiles . On the other hand, the evanescent-wave coupling Ω mm ′ between arbitrary resonances can be evaluated by calculating the overlap between the mode profiles of the resonances. , In the steady state, the amplitudes of the outgoing plane wave S out ( i ) for the working frequency ω 0 can be obtained by substituting a = a (ω 0 ) e jω 0 t and S in ( i ) = S in ( i ) (ω 0 ) e jω 0 t into eqs and : where I M × M is the M by M identity matrix. Equation allows us to calculate the amplitude, phase, or intensity of the far-field scattered wave at any location.…”

“…These parameters can be obtained from simulations of isolated resonators. Once we obtain the quality factor and radiation profile, the evanescent-wave coupling Ω mm ′ can be either obtained analytically or numerically. , …”

“…Coupled-mode theory (CMT) is a powerful framework that has been widely used to model optical resonances with high accuracy. , However, CMT has been mostly used to fit spectra obtained from simulations or experiments. Lin et al recently demonstrated the capability of CMT to design the spectrum of a periodic array of coupled resonators . However, the design of far-field profiles using CMT-engineered metasurfaces remains unexplored.…”

Manipulating strong coupling between exciton and quasi-bound states in the continuum resonance

“…In recent years, many researchers have investigated strong coupling between the TMDs and plasmonic/dielectric nanostructures [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] , and developed a general approach to employ the coupled harmonic oscillator model for such hybrid systems, in which nanostructures are treated as an isolated system and the influence of external excitation is ignored. However, the coupled systems are open in nature, where different resonant modes couple not only with each other via near field but also with the external free space 33 . Therefore, an analytical theory that can consider the near field and external free space in the same foot is in urgent need.…”

From Lingering to Rift: Metasurface Decoupling for Near‐ and Far‐Field Functionalization

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Metasurfaces, artificially engineered planar structured surfaces with feature size less than half a wavelength, have been proven to be able to effectively manipulate the polarization, [1][2][3][4][5] amplitude, [6][7][8] and phase [9][10][11][12][13][14][15][16][17][18][19] of an optical wave at the subwavelength scale. By manipulating light's properties with a more degree of freedom, various metasurfaces have been proposed recently to construct specific light field distribution

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