Measurement and Modeling of a Complete Optical Absorption and Scattering by Coherent Surface Plasmon-Polariton Excitation Using a Silver Thin-Film Grating

Jae Woong Yoon, Gang Min Koh, Seok Ho Song, and Robert Magnusson

Phys. Rev. Lett. 109, 257402 – Published 21 December 2012

Abstract

We demonstrate the plasmonic analogue of a coherent photonic effect known as coherent perfect absorption. A periodically nanopatterned metal film perfectly absorbs multiple coherent light beams coupling to a single surface plasmon mode. The perfect absorbing state can be switched to a nearly perfect scattering state by tuning the phase difference between the incident beams. We theoretically explain the plasmonic coherent perfect absorption by considering time-reversal symmetry of surface plasmon amplification by stimulated emission of radiation. We experimentally demonstrate coherent control of the plasmonic absorption in good agreement with a coupled-mode theory of dissipative resonances. Associated potential applications include absorption-based plasmonic switches, modulators, and light-electricity transducers.

Received 31 January 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.257402

Authors & Affiliations

Jae Woong Yoon¹, Gang Min Koh², Seok Ho Song^2,*, and Robert Magnusson¹

¹Department of Electrical Engineering, University of Texas-Arlington, Arlington, Texas 76019, USA
²Department of Physics, Hanyang University, Seoul 133-791, Korea

^*Corresponding author. shsong@hanyang.ac.kr

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Vol. 109, Iss. 25 — 21 December 2012

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Images

Figure 1
(a) Schematic of plasmonic CPA with two coherent light waves with amplitudes $α_{1}$ and $α_{2}$ incident on a periodic Ag surface. The incoming waves couple to the SPP dissipating energy by Ohmic loss. Time reversing this situation corresponds to SPASER emission at threshold in (b) where the SPP is initially excited by gain from Ag with dielectric constant $ε_{Ag}^{*}$ and the SPP emits radiation $β_{1} = Φ_{1}^{*}$ and $β_{2} = Φ_{2}^{*}$ .Reuse & Permissions
Figure 2
Calculated angular spectrum of the absorbance relative to Ohmic damping factor $f_{nr}$ at (a) $λ = 440 nm$ and (b) $λ = 580 nm$ ; (c) and (d) show total decay rate $γ_{tot}$ of the SPP obtained by measuring absorbance linewidth. $γ_{rad}$ is estimated by linearly extrapolating $γ_{tot}$ (solid square symbols) to $f_{nr} = 0$ as schematically indicated in (d). Panels (e) and (f) show the dependence of $\det (S)$ on $f_{nr}$ at $λ = 440 nm$ and 580 nm. Real (blue squares) and imaginary (red circles) parts of $\det (S)$ simultaneously vanish at $f_{nr} = 0.44$ for $λ = 440 nm$ in (e) and at $f_{nr} = 0.48$ for $λ = 580 nm$ in (f).Reuse & Permissions
Figure 3
CPA by two coherent Gaussian laser beams at $λ = 580 nm$ . The white, horizontal line near the top of each panel indicates the Ag grating surface. Each panel shows the surface-normal component of the time-averaged Poynting vector. The 3D surface plot in the inset shows surface-normal electric field distribution in the optical near field at the incident beam center. (a) Single beam excitation at $q = 1$ . (b) Single beam excitation at $q = 2$ . (c) Coherent in-phase excitation for $(α_{1}, α_{2}) = (Φ_{1}, Φ_{2})$ . (d) Coherent out-of-phase excitation for $(α_{1}, α_{2}) = (Φ_{1}, - Φ_{2})$ .Reuse & Permissions
Figure 4
Scanning electron micrograph of the fabricated Ag grating on Si substrate: (a) top view and (b) the cross section. (c) Measured angular spectra of the diffraction efficiencies ( $R_{0}$ and $R_{- 1}$ ) and the absorbance ( $A$ ) near SPP resonance conditions at $θ = 9.215 °$ $q = 1$ ) and $- 45.712 °$ $q = 2$ ). He-Ne laser ( $λ = 632.8 nm$ ) was used for the measurement.Reuse & Permissions
Figure 5
(a) Schematic of the Mach-Zehnder type interferometer used for phase-controlled absorption measurements. Two laser beams at $q = 1$ ( $I_{1}$ , blue) and 2 ( $I_{2}$ , red) are incident on the sample. Piezoelectric mirror ( $M 2$ ) controls phase difference between $I_{1}$ and $I_{2}$ . PD1 and PD2 (Si photodiodes) measure outgoing power $P_{1}$ at $q = 1$ and $P_{2}$ at $q = 2$ , respectively. Measured $P_{1}$ (blue), $P_{2}$ (red), and their total $P_{tot} = P_{1} + P_{2}$ (black) are presented in (b) for incident power ratio $I_{2} / I_{1} = A_{2} / A_{1} = 0.815$ and in (c) for $I_{2} / I_{1} = 0.05$ . (d) Coherent (blue) and incoherent (red) outgoing optical power with varying incident power ratio $I_{2} / I_{1}$ . Symbols with vertical error bars correspond to experiment and the curves represent theory.Reuse & Permissions

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