A tunable slow light thermal modulator using 2D semiconductor metamaterial is presented and investigated. We have designed and simulated a terahertz (THz) semiconductor metamaterial (MM) waveguide system; The simulation results show the spectral properties and the group delay of the proposed 2D metamaterial can be tuned by adjusting temperature and the semiconductor used in the waveguide. Our calculations exhibit a significant slow-light effect, based on electromagnetically induced transparency (EIT) effect. By appropriately adjusting the distance between the sub radiant and supper radiant modes, a flat band corresponding to nearly constant group delay (of order of 71) over a narrow bandwidth of THz regime can be achieved. Our analytical results show that the group velocity dispersion (GVD) parameter can reach zero. The simulation results show the incident pulse can be slowed down without distortion owing to the low group velocity dispersion (LGVD). The outstanding result is that, the 2D semiconductor metamaterial is in a high decrease of the group velocity and therefore slow light applications. The proposed compact slow light thermal modulator can avoid the distortion of signal pulse, and thus may find potential applications in slow-light and thermal modulator devices and thermal applications.
A tunable slow light thermal modulator using 2D semiconductor metamaterial is presented and investigated. We have designed and simulated a terahertz (THz) semiconductor metamaterial (MM) waveguide system; The simulation results show the spectral properties and the group delay of the proposed 2D metamaterial can be tuned by adjusting temperature and the semiconductor used in the waveguide. Our calculations exhibit a significant slow-light effect, based on electromagnetically induced transparency (EIT) effect. By appropriately adjusting the distance between the sub radiant and supper radiant modes, a flat band corresponding to nearly constant group delay (of order of 71) over a narrow bandwidth of THz regime can be achieved. Our analytical results show that the group velocity dispersion (GVD) parameter can reach zero. The simulation results show the incident pulse can be slowed down without distortion owing to the low group velocity dispersion (LGVD). The outstanding result is that, the 2D semiconductor metamaterial is in a high decrease of the group velocity and therefore slow light applications. The proposed compact slow light thermal modulator can avoid the distortion of signal pulse, and thus may find potential applications in slow-light and thermal modulator devices and thermal applications.
Abstract Tunable slow light systems have gained much interests recently due to their efficient control of strong light–matter interactions as well as their huge potential for realizing tunable device applications. Here, a dynamically tunable polarization independent slow light system is experimentally demonstrated via electromagnetically induced transparency (EIT) in a terahertz (THz) metasurface constituted by plus and dimer-shaped resonators. Optical pump-power dependent THz transmissions through the metasurface samples are studied using the optical pump THz probe technique. Under various photoexcitations, the EIT spectra undergo significant modulations in terms of its resonance line shapes (amplitude and intensity contrast) leading to dynamic tailoring of the slow light characteristics. Group delay and delay bandwidth product values are modulated from 0.915 ps to 0.42 ps and 0.059 to 0.025 as the pump fluence increases from 0 to 62.5 nJ cm−2. This results in tunable slow THz light with group velocities ranging from 2.18 × 105 m s−1 to 4.76 × 105 m s−1, almost 54% change in group velocity. The observed tuning is attributed to the photo-induced modifications of the optoelectronic properties of the substrate layer. The demonstrated slow light scheme can provide opportunities for realizing dynamically tunable slow light devices, delay lines, and other ultrafast devices for THz domain.
In this Letter, we construct a metamaterial with dual-mode electromagnetically induced transparency (EIT)-like behavior by introducing "bright atoms," "quasi-dark atoms," and "dark atoms" simultaneously. The dual-mode EIT-like behavior has been demonstrated both experimentally and theoretically in terahertz (THz) regime. At two EIT-like modes, slow light is also observed as two time-delayed wave packets, and the effective group refractive index can reach 10(2). Furthermore, stable dual-mode EIT-like behavior is verified in this metamaterial for a wide range of oblique incident angles. Our work provides a design approach to mimic dual-mode EIT, and such an approach may achieve potential applications on miniaturized and versatile THz devices.
Recently reported metamaterial (MM) analogs of electromagnetically induced reflectance (EIR) enable a unique route to endow classical optical structures with aspects of quantum optical systems. This method opens up many fascinating prospects on novel optical components, such as slow light units, highly sensitive sensors, and nonlinear devices. Here we designed and simulated a microwave MM made from aluminum thin film to mimic the EIR system. High reflectance of about 99 percent and also a large group index at the reflectance window of about 243 are demonstrated, which mainly arise from the enhanced coupling between radiative and nonradiative elements. The interaction between the elements of the unit cell, induced directly or indirectly by the incident electromagnetic wave, leads to a reflectance window, resembling the classical analog of EIR. This reflectance window, caused by the coupling of radiative-nonradiative modes, can be continuously tuned in a broad frequency regime. The strong normal phase dispersion in the vicinity of this reflectance window results in the slow light effect. This scheme provides an alternative way to achieve tunable slow light in a broad frequency band and can find important applications in active and reversibly tunable slow light devices.
Abstract The realization of electromagnetically induced transparency (EIT) on metamaterials has special properties, such as strong slow-light, frequency-selection and so on, which have allowed EIT to be widely used in the fields of slow-light, optical storages and filters. In this paper, a metamaterial with two pairs of split ring resonators and one cut-wire is designed to achieve dual-band EIT effect at 0.5–2.14 GHz and 0.4–2.10 GHz with independently tunable bandwidths of 1.64 GHz and 2.7 GHz, respectively. The coupled Lorentz model is adopted to principally study the coupling characteristics between dark and bright modes. It is shown that the coupling strength between the dark and bright modes could be modulated by the coupling distance, which make the dual-band transparent window could be independently modulated by only changing the coupling distance between the bright and dark mode. The group delay and energy storage are also simulated by setting the Gaussian pulse signal passing through the EIT structure. The results show that the group delay of the designed EIT structure is 16.9 times that of the same thickness of dielectric material. The manufactured metamaterial is tested in a microwave anechoic chamber. The experimental and theoretical results are well consistent. These results could be beneficial for the development of EIT research toward some up-and-coming novel slow-light, optical storage, sensor and optical filter applications.
We propose a novel metamaterial structure to realize dispersionless slow light based on plasmon-induced transparency (PIT) at optical frequency. Simply by breaking the symmetry of the metamaterial structure, two electric excitation coupling to the magnetic resonance (EEMR) modes generate and interplay with each other resulting the formation of the PIT resonance. Due to the hybridization of the two EEMR modes, an ultrabroad flat-band as large as 15 THz with average group index of ~5 is obtained. The corresponding normalized delay-bandwidth product is 0.475, which indicates the prominent feature in light slowing down without distortion. The proposed metamaterial structure is promising for practical information storage, optical memory, and optical buffers design.
Based on solid-state plasma (SSP), an electromagnetically induced transparent (EIT) metamaterial is proposed. Simulations illustrate that the given metamaterial has the characteristics of adjustment, polarization insensitivity, and low dissipation. Because SSP can be coordinated in state I, the ideal transmittance frequency band can cover 8.0335–9.02531 GHz (a narrow band). If the regulatory status is switched to state II, that frequency region will alter to 9.7982–12.9275 GHz (a broad band). As SSP can be switched back and forth between states I and II under actual demand, the tailored EIT metamaterial can be achieved. The maximum group delays of state I and state II are 0.9437 ns and 0.5546 ns, respectively, and the maximum group refractive indices are 526.60 and 300.45, respectively, which conforms to its slow light characteristic. Regardless of how the polarization angle changes, the two transmission valleys of state I are at 7.9172 GHz and 10.4446 GHz, and the transmission peak is situated at 8.2091 GHz, and those values of state II are 9.3777 GHz, 13.9600 GHz, and 10.1920 GHz, respectively, which proves that the obtained EIT is polarization independent and also has a low dissipation factor. Such an EIT metamaterial has excellent properties in sensing, communication, slow light, and other fields.