Transparency-like Effect Research Articles

Polarization manipulation based on electromagnetically induced transparency-like (EIT-like) effect

We proposed, designed and fabricated a high transparency of metasurface-based polarization controller at microwave frequencies, which consists of orthogonal two pairs of cut wires. The high transmission and the strong dispersion properties governed by electromagnetically induced transparency-like (EIT-like) effects for both incident polarizations make our device efficiently manipulating the polarization of EM waves. In particular, the proposed polarization device is ultrathin (~0.017λ), as opposed to bulky polarization devices. Microwave experiments are performed to successfully demonstrate our ideas, and measured results are in reasonable agreement with numerical simulations.

Wide-angle and polarization-independent electromagnetically induced transparency-like effect based on pentacyclic structure

A pentacyclic structure analog wide-angle and polarization-independent electromagnetically induced transparency-like (EIT-like) effect is numerically and experimentally demonstrated. The unit cell of the structure is composed of four identical circular inner rings surrounded by a larger circular outer ring. A wide-angle and polarization-independent transparency window is clearly observed in the spectral overlapping region of absorption bands of the inner and outer rings. The resonant feature of the transparency effect is investigated by the surface current distribution. We find that the coupling fields between rings play key roles and lead to the classical EIT-like effect. It is also shown that the polarization direction in our structure can be used to tune the position of the localized electric field enhancement. In addition, the effective group index and the effective refractive index are extracted to verify the slow light property with low loss. It is shown that our structure can reduce the group velocity of light by a factor of 64.

Polarization-independent electromagnetically induced transparency-like effects in stacked metamaterials based on Fabry–Pérot resonance

We propose a scheme for realizing plasmonic electromagnetically induced transparency (EIT)-like effects at optical frequencies in a stacked metamaterial that consists of two silver rings. The two silver rings are excited strongly by an incident wave. Based on Fabry–Pérot (FP) resonance coupling between the two resonators, polarization-independent EIT-like effects appear at optical frequencies.

Dependence of transmittance and group index on the coupling strength between constituents of a metamaterial

Recent studies on the coupling effects between constituent elements of metamaterials have opened up a new gateway to many fascinating electromagnetic properties and functionalities that cannot be explained by the uncoupled point of view. In this work, we numerically investigated, in a THz regime, the coupling between a cut wire and a split-ring resonator, which gives rise to an interesting phenomenon—the so-called electromagnetically induced transparency-like effect. The trade-off between the maximum transmittance of the transmission window and the group index, which depends on the coupling strength between constituent elements, was systematically studied. Furthermore, by characterizing this trade-off by the transmittance-delay product (figure of merit), a criterion for slow-light applications was provided.

Electromagnetically induced transparency-like effect in a single polydimethylsiloxane-coated silica microtoroid

We study both experimentally and theoretically the coupling between a fiber taper and two whispering-gallery modes, which are simultaneously excited in a single pilydimethyl-siloxane-coated silica microtoroid system. The transmission spectrum of the fiber-coupled two-mode microresonator shows a sharp electromagnetically induced transparency-like window within the resonant absorption region. This line shape results from destructive interference between two optical pathways associated with two distinct coexisting modes in a single resonator. The sharp transparency peak has great potential applications in light modulation and highly sensitive biochemical sensors.

Electromagnetically induced transparency-like effect in the degenerate triple-resonant optical parametric amplifier

We investigate experimentally the absorptive and dispersive properties of the triple-resonant optical parametric amplifier (OPA) for the degenerate subharmonic field. In the experiment the subharmonic field is utilized as the probe field and the harmonic wave as the pump field. We demonstrate that the electromagnetically induced transparency (EIT)-like effect can be simulated in the triple-resonant OPA when the cavity linewidth for the harmonic wave is narrower than that for the subharmonic field. However, this phenomenon cannot be observed in a double-resonant OPA. The narrow transparency window appears in the reflected field. Especially in the measured dispersive spectra of the triple-resonant OPA, a very steep variation of the dispersive profile of the subharmonic field is observed, which can result in a slow light as that observed in an atomic EIT medium.

Generation of high-power laser light with Gigahertz splitting

We demonstrate the generation of two high-power laser beams whose frequencies are separated by the ground state hyperfine transition frequency in (87)Rb. The system uses a single master diode laser appropriately shifted by high frequency acousto-optic modulators and amplified by semiconductor tapered amplifiers. This produces two 1 W laser beams with a frequency spacing of 6.834 GHz and a relative frequency stability of 1 Hz. We discuss possible applications of this apparatus, including electromagnetically induced transparency-like effects and ultrafast qubit rotations.

Absorptive and dispersive properties in the phase-sensitive optical parametric amplification inside a cavity

In this paper we investigate the absorptive and dispersive properties in the phase-sensitive optical parametric amplification inside a cavity. First, we study the single-resonant optical parametric amplifier theoretically and experimentally. In this case, the mode splitting in the transmission spectra and the M shape in the reflection spectra are observed. However, the shape of the phase shift of the reflected field is unchanged. Then, the double-resonant optical parametric amplifier is studied theoretically, in which electromagnetically induced transparency-like effect may be emulated when the cavity linewidth for the harmonic wave is narrower than for the subharmonic field. The narrow transparency window appears in the absorption spectrum and is accompanied by a very steep variation of the dispersive profile.

Refractive-index control with strong fields

An electromagnetically induced transparency-like effect is described that allows a strong laser to control and reduce to unity the refractive index of a weak probe. A lossless multistate system with all states far from resonance is considered.