An electromagnetic modulator based on electrically controllable metamaterial analogue to electromagnetically induced transparency

Abstract

Electromagnetically induced transparency (EIT) is a promising technology for the enhancement of light-matter interactions, and recent demonstrations of the EIT analogue realized in artificial micro-structured medium have remarkably reduced the extreme requirement for experimental observation of EIT spectrum. In this paper, we propose to electrically control the EIT-like spectrum in a metamaterial as an electromagnetic modulator. A diode acting as a tunable resistor is loaded in the gap of paired wires to inductively tune the magnetic resonance, which induces remarkable modulation on the EIT-like spectrum through the metamaterial sample. The experimental measurements confirmed that the prediction of electromagnetic modulation in three narrow bands on the EIT-like spectrum, and a modulation contrast of up to 31 dB was achieved on the transmission through the metamaterial. Our results may facilitate the study on active/dynamical technology in translational metamaterials, which connect extraordinary manipulations on the flow of light in metamaterials, e.g., the exotic EIT, and practical applications in industry.

Figure 1

(a) Schematic illustration of the proposed metamaterial switch composed of a single wire (left) coupled with a wire pair (right), a PIN diode is located in the gap of the wire pair for active modulation, geometric parameters of the metamaterial are denoted with black letters. (b) Photograph of a sample fabricated for experimental measurement.

Figure 2

(a) Calculated transmission (in dB) spectra of a single warped wire (blue solid), a pair of warped wires (green solid), and the metamaterial with coupled single wire and wire pair (red solid). The distributions of the out-of-plane magnetic fields (black arrows illustrate the surface currents) at the frequency of 5.17 GHz are plotted for a metamaterial composed of a single wire and a wire pair with lumped resistance of 10 Ω (b), 7000 Ω (c).

Figure 3. Conductivity dependence of the transport through a metamaterial switch.

(a) Plot of the simulated transmission spectra (in dB) for a serious of lumped resistance (from 7000 Ω to 10 Ω). (b) Measured transmission of the metamaterial switch sample under different biasing voltage changing from 0.1 V to 1.2 V.

Figure 4. Measured transmission (in dB) versus biasing voltage on the diode (from 0 to 1.2 V) at the three switching frequencies.

The transmission are plotted for the EIT-like peak frequency 5.25 GHz (red), EIT-like dip frequencies 4.81 GHz (blue) and 5.62 GHz (green).