Fast Light Effects Research Articles

Chirp-driven control over fast-slow light effects in epsilon-near-zero metamaterials.

Optical applications based on fast and slow light effects force the usage of metamaterials famous for their flexible dispersion properties. In this work, we apply the unique optical nonlocality of metal nanorod-based epsilon-near-zero (ENZ) metamaterials along with the chirp of femtosecond laser pulses for astonishing control of these effects. We demonstrate the switching between the fast and slow light phenomena via the change of the angle of incidence and/or the central wavelength of chirped pulses in the vicinity of metamaterial zero-transmission regime mediated by the ENZ nonlocality. We elucidate that the laser chirp allows one to manipulate and enhance the fast-slow light phenomena.

Triple electromagnetically induced transparency generated slow light for multiple carbon nanotube resonators

Hybrid spin-mechanical systems offer a promising platform for advancing quantum science and technology. However, practical implementation of applications within these hybrid quantum systems demands the seamless integration of supplementary physical components. In this context, we present a proposal for a multi-mode spin-mechanical setup, featuring the utilization of three-mode coupling nanomechanical carbon nanotube (CNT) resonators. These resonators interact with each other via a phase-dependent phonon-exchange mechanism, which is coupled to the same nitrogen vacancy (NV) centers in diamond. Based on the modulation of the phonon–phonon coupling phase and leveraging the triple Fano-like resonance phenomenon, a tripling of electromagnetically induced transparency (EIT) becomes achievable within the system. This tripling is accompanied by swift dispersion, leading to a subtle advancement or delay in outcomes. The phenomenon of triple Fano-like resonance, alongside the resulting triple EIT, engenders noteworthy slow-to-fast and fast-to-slow light effects, which is theoretically demonstrated in CNT resonators, with both identical and distinct frequencies. The findings underscore that CNT resonators with varying frequencies can evoke a more pronounced transition in the slow–fast–slow and fast–slow–fast light effects. This study lays the foundation for the application of phonon-mediated optical information storage and processing.

Kerr nonlinearity assisted magnetically induced transparency in cavity magnon polaritons.

We investigate optical transmission in cavity magnon polaritons and discover a complex multi-window magnetically induced transparency and a bistability with magnetic and optical characteristics. With the regulation of Kerr nonlinear effects and driven fields, a complex multi-window resonant transmission with fast and slow light effects appears, which includes transparency and absorption windows. The magnetically induced transparency and absorption can be explained by the destructive and constructive interference between different excitation pathways. Moreover, we demonstrate the bistability of magnons and photons with a hysteresis loop, where magnetic and optical bistabilities can induce and control each other. Our results pave a new way, to the best of our knowledge, for implementing a room-temperature multiband quantum memory.

All-optical group velocity manipulation in Mach-Zehnder fiber interferometers incorporating with Brillouin random lasing resonance

We proposed and experimentally demonstrated a novel scheme of light group velocity control via a Mach-Zehnder fiber interferometer incorporated with Brillouin random lasing resonance in a half-open linear cavity. A theoretical model of the proposed Brillouin random lasing resonance-based Mach-Zehnder interferometer (BRLR-MZI) for the light group velocity manipulation was derived, predicting optical power-dependent transmittance spectrum shift as well as the enhancement of the temporal advancement. Thanks to Brillouin random lasing-induced fast light effect, the proposed scheme not only achieves a flexible all-optical manipulation of its transmittance spectrum but also overcomes the saturation effect for the light speed control based on a traditional MZI. In experimental validation, sinusoidally modulated signals with the modulation frequency of 160 kHz ultimately experienced a maximum advancement of 4031 ns (corresponding to the group index of 0.875), which exhibits an advancement improvement of 1364 ns compared with the traditional MZI-based scheme. It suggests a promising platform for exploring applications in fields of all-optical signal processing, microwave photonic, and ultra-sensitive fiber sensing.

Tunable electromagnetically induced absorption based on coupled-resonators in a compact plasmonic system.

Electromagnetically induced absorption (EIA) exhibits abnormal dispersion and novel fast-light features, making it a crucial aspect of nanophotonics. Here, the EIA phenomenon is numerically predicted in a compact plasmonic waveguide system by introducing a slot resonator above a square cavity. Simulation results reveal that the EIA response can be easily tuned by altering the structure's parameters, and double EIA valleys can be observed with an additional slot resonator. Furthermore, the investigated structures demonstrate a fast-light effect with an optical delay of ∼ -1.0 ps as a result of aberrant dispersion at the EIA valley, which enable promising applications in the on-chip fast-light area. Finally, a plasmonic nanosensor with a sensitivity of ∼1200 nm/RIU and figure of merit of ∼16600 is achieved based on Fano resonance. The special features of our suggested structure are applicable in realization of various integrated components for the development of multifunctional high-performance nano-photonic devices.

Photonic transistor based on a coupled-cavity system with polaritons.

We investigate the transmission of probe fields in a coupled-cavity system with polaritons and propose a theoretical schema for realizing a polariton-based photonic transistor. When probe light passes through such a hybrid optomechanical device, its resonant point with Stokes or anti-Stokes scattered effects, intensity with amplification or attenuation effects, as well as group velocity with slow or fast light effects can be effectively controlled by another pump light. This controlling depends on the exciton-photon coupling and single-photon coupling. We also discover an asymmetric Fano resonance in transparency windows under the strong exciton-photon coupling, which is different from general symmetric optomechanically induced transparency. Our results open up exciting possibilities for designing photonic transistors, which may be useful for implementing polariton integrated circuits.

Auxiliary-Cavity-Assisted Slow and Fast Light in a Photonic Molecule Spinning Optomechanical System

We investigate the coherent optical propagation in a photonic molecule spinning optomechanical system consisting of two whispering gallery microcavities in which one of the optical cavities is a spinning optomechanical cavity and the other one is an ordinary auxiliary optical cavity. As the optomechanical cavity is spinning along the clockwise or counterclockwise direction, the cavity field can undergo different Sagnac effects, which accompanies the auxiliary optical cavity, together influencing the process of the evolution of optomechanically induced transparency and its related propagation properties, such as fast and slow light effects. The numerical results indicate that the enhanced slow and fast light and the conversion from fast to slow light (or slow to fast light) are determined by the spinning direction of the optomechanical cavity and the coupling of the two optical cavities. The study affords further insight into the photonic molecule spinning optomechanical systems and also indicates promising applications in quantum information processing.

Significantly enhanced slow light effect in magnon–photon coupling system via cross-Kerr interaction

We theoretically analyze the transmission characteristics of a magnon–photon coupling system based on ultrastrong optomechanical-like coupling via the cross-Kerr interaction. We use the definition of group delay to characterize the fast and slow light effects. It is found that the group delay of our system can be significantly improved by two to three orders of magnitude compared to previous studies in magnon–photon coupling systems, which means slow light effect can be significantly enhanced. By adjusting the driving power and frequency detuning of the microwave cavities, the magnitude and bandwidth of the group delay and transmittance can be adjusted precisely. Moreover, frequency control of slow light can be achieved by manipulating the strength of magnetic field. The influence of the cross-Kerr coupling strength of cavities on the system is also discussed in detail. The group delay of the system is close to milliseconds, while the transmittance is greatly improved. The result from this paper hopes to bring new development possibilities for the fabrication of optical memory and the construction of all-optical networks.

Switchable fast-slow light in a cavity-magnon system by adding a squeezed drive field

We theoretically discuss the influence of a squeezed drive on the fast and slow light effect at different temperatures by focusing on two main factors: the nonlinear gain coefficient of optical parametric amplification and the phase of the pumping field. We show that the nonlinear gain coefficient and the phase of the pump field will affect the coupling strength between photon and magnon, which provides a way to achieve more obvious fast and slow light effects and good potential to realize the fast-slow light conversion. Moreover, by comparing two different temperatures, we find that the low temperature environment is more conducive to the production of fast light and slow light. With the addition of the squeezing drive field, the group delay of the system will get a larger value and the symmetry of the system will be destroyed, leading to asymmetric absorption. Our results provide more freedom for the realization and conversion of fast and slow light and is expected to find applications in optical communication and optical storage.

Nonlocality-driven switchable fast-slow light effect in hyperbolic metamaterials in epsilon-near-zero regime

The recent surge of optics of hyperbolic metamaterials (HMMs) has been fueled by their fascinating optical properties, one of the most intriguing being their strong optical nonlocality. In this work we demonstrate that in metal nanorod-based HMMs the nonlocality results in fast and slow light effects in the propagation of femtosecond laser pulses in close spectral vicinity of the HMM epsilon-near-zero regime. These effects are switchable via the angle of incidence and light wavelength. We elucidate that revealed dynamical phenomena stem from the zero-transmission points of HMM and related phase singularities caused by the destructive interference of the main optical wave and the additional wave mediated by the spatial dispersion of light in the HMMs.

Revisit the Poynting vector in P T-symmetric coupled waveguides.

We show that the time-averaged Poynting vector of S→=E→×H→∗/2 in parity-time (P T) symmetric coupled waveguides is always positive and cannot explain the stopped light at exceptional points (EPs). In order to solve this paradox, we must accept the fact that the fields E→ and H→ and the Poynting vector in non-Hermitian systems are in general complex. Based on the original definition of the instantaneous Poynting vector S→=E→×H→, a formula on the group velocity is proposed, which agrees perfectly well with that calculated directly from the dispersion curves. It explains not only the stopped light at EPs, but also the fast-light effect near it. This investigation bridges a gap between the classic electrodynamics and the non-Hermitian physics, and highlights the novelty of non-Hermitian optics.

The fast and slow light in a hybrid spinning optomechanical system mediated by a two-level system

We present a hybrid spinning whispering-gallery-mode (WGM) optomechanical system, where the mechanical resonator is not only coupled to the WGM cavity via radiation pressure but also coupled to a two-level system (TLS) via the Jaynes–Cummings coupling. If the WGM cavity is spinning along the clockwise or counterclockwise direction, the cavity field can undergo different Sagnac effect. The transmission spectra experience the conversion from optomechanically induced transparency (OMIT) to Fano resonance by controlling the resonator-TLS coupling, the rotational direction of the WGM cavity, and the cavity-pump detuning. Furthermore, both the OMIT and Fano resonance in the transmission spectra can induce the transparency windows accompanied by the rapid normal phase dispersion, which results in the tunable delayed or accelerated probe light transmission. The numerical results indicate that the OMIT leads to slow light, while Fano resonances generate the conversion from fast to slow light (or slow to fast light), and the parameters of the resonator-TLS coupling, the Sagnac frequency shift, the pump field frequency, and the cavity-pump detuning together determine the fast and slow light effect based on the hybrid spinning optomechanical system.

Carbon nanotube resonator enhancement of Majorana fermions induced slow light in a hybrid semiconductor/superconductor device

We theoretically investigate the Rabi-like splitting in the absorption spectrum of a single electron spin mediated by Majorana fermions in a hybrid semiconducting nanowire/superconductor system. The absorption spectra can display the symmetrical splitting phenomenon, and their related optical propagation such as fast light and slow light are investigated in different parametric regimes. When we consider implanting a spin into the carbon nanotube (CNT) resonator, the Rabi-like splitting in the absorption spectrum changes into asymmetric Fano resonance, which is accompanied by the rapid steep dispersion promising the slow- or fast-light effect, and even reaching tunable fast-to-slow light propagation (or vice versa) with controlling different parameter regimes. Moreover, we also investigate the role of the CNT resonator, which behaves as a phonon cavity enhancing the fast and slow light effect.

Theoretical study on fast and slow light effects in semiconductor optical amplifiers under assist light injection

In this paper, the fast and slow light effect of semiconductor optical amplifiers (SOAs) under assist light injection is theoretically analyzed. Coherent population oscillation (CPO) is used to induce fast and slow light effect in the theoretical model. The effects of parameters such as modulation frequency, modulation current and assist optical power on phase delay are investigated under the assist light injection. These effects are then compared with the case without assist light injection. The simulation results show that the injection of assist light can increase the phase delay of the output optical signal and enhance the slow light effect. Furthermore, when the assist light optical power is in the range of 0–15 dBm, the slow light effect is strong.

Controllable fast light in quantum dot molecules assisted hybrid optomechanical system

AbstractWe investigate the superluminal effect of transmitted probe field in three‐level quantum dot molecules (QDMs) assisted optomechanical system which consist of mechanical resonator. We show that the superluminal behavior of transmitted probe field can be controlled by changing the tunneling strength and number of QDMs inside the cavity. Furthermore, it is shown that in the absence of tunneling strength, the transmitted probe field shows the fast light effect and by increasing the number of QDMs, the enhancement in superluminal behavior is decreased and converts into slow light. While, in the presence of the tunneling strength, with the increase of the number of QDMs the superluminal behavior of transmitted field is obtained at smaller detuning frequency. The influence of tunneling strength and number of QDMs on superluminal part of the transmitted probe field is quite useful in optical memory, optical buffers, and quantum information processing.

Numerical analysis of slow and fast light effect in semiconductor optical amplifier with certain facet reflection

In this paper, the slow and fast light (SFL) effects of the semiconductor optical amplifier (SOA) having certain facet reflections are theoretically investigated. The theoretical model is used to account for the SFL phenomenon causing the coherent population oscillation. The influence of the current modulation frequency, the value of the current, the linewidth enhancement factor, facet reflectivity as well as the relative phase of the modulated current on the phase delay in the SOA are studied. It is demonstrated that the SFL effect could be controlled by the modulation frequency, the value and relative phase of the current. Finally, it is shown that the magnitude of the SFL delay could be tuned by a change in the linewidth enhancement factor as well as the facet reflectivity of the SOA.

Phonon pump enhanced fast and slow light in a spinning optomechanical system

We investigate the properties of the optical output fields in a spinning optomechanical system under the condition of optomechanically induced transparency (OMIT), where the cavity is optically driven by a strong pump field and a weak probe field and the mechanical resonator is driven by a coherent phonon pump. When the driven frequency of the phonon pump equals the frequency difference of the pump and probe fields, we show an enhancement OMIT, where the probe transmission can exceed unity via controlling the amplitude and phase of the phonon pump. Furthermore, the phase dispersion of the transmitted probe field is modified with manipulating the spinning direction of the resonator, which leads to a tunable delayed probe light transmission, due to the clockwise and counterclockwise optical fields in the resonator undergo the different Sagnac effect. Combining Sagnac effect, we demonstrate that the large positive or negative group delay of the output probe field can be achieved by adjusting the phase and amplitude of the coherent phonon pump, which can realize a tunable conversion between the slow and fast light effect with manipulating the spinning direction of the resonator, power of the pump field as well as the amplitude and phase of the phonon pump.

Controllable fast and slow light in the hybrid quantum dot–nanomechanical resonator system mediated by another nanomechanical resonator with Coulomb interaction

We theoretically propose a hybrid nanomechanical resonator (NR) system, where a doubly clamped suspended NR with an embedded quantum dot driven by two-tone fields is coupled to another NR via the Coulomb interaction, and we investigate the absorption spectra of the probe field under different exciton-pump field detuning. In the condition of pump on-resonance, the absorption spectrum gives a method to determine the coupling strength of the two NRs. In the pump off resonance, the absorption spectra exhibit double-Fano resonance, which is determined by the interaction of the two NRs, the frequencies of the two NRs, as well as the pump detuning. Furthermore, the double-Fano resonances are accompanied by the rapid normal phase dispersion, which indicates the slow- and fast-light effect. The results show that the group velocity index is tunable by the interaction of the two NRs, the detuning, and the different resonator frequencies, which can achieve the conversion from fast light to slow light.

Multiple-Fano-resonance-induced fast and slow light in the hybrid nanomechanical-resonator system

We investigate the multiple-Fano-resonance-induced fast and slow light in a hybrid nanomechanical-resonator (NR) system, where a doubly clamped suspended NR with an embedded quantum dot driven by two-tone fields is coupled to another two NRs with different frequencies via the Coulomb interaction. We display the absorption spectra of the weak probe field under different exciton-pump field detuning, and the sharp peaks in the absorption spectra are determined by the interaction between the NRs under the resonance. In the off-resonance, the absorption spectra can exhibit multiple Fano resonance, and the positions of the multiple Fano resonances are related to the interaction between the NRs and the frequencies of the different NRs. Furthermore, the multiple Fano resonances are accompanied by the rapid normal phase dispersion, which indicates the slow- and fast-light effect. We obtain that the group velocity index is tunable by the interaction between the NRs and the detuning, which can reach the conversion between the fast and slow light.

Optomechanically Induced Transparency and Slow–Fast Light Effect in Hybrid Cavity Optomechanical Systems

We theoretically investigate the optomechanically induced transparency (OMIT) phenomenon and the fast and slow light effects of a four-mode optomechanical system with the Kerr medium. The optomechanical system is composed of an array of three single-mode cavities and a mechanical oscillator. The three cavities are a passive cavity, a no-loss-gain cavity and a gain optical cavity, respectively. A Kerr medium is inserted in the passive cavity. We study the influence of the Kerr medium on the stability of the optomechanical system, and find that the stable regime of the optomechanical system can be adjusted by changing the Kerr coefficient. We demonstrate that the phenomenon of optomechanically induced transparency will appear when the Kerr medium exists in the optomechanical system and find that the frequency position of the absorption peak on the left increases linearly with the Kerr coefficient. In addition, we also investigate the fast and slow light effects in this system. The results show that we can control the fast and slow light by adjusting the Kerr coefficient, tunneling strength, and driving field strength. This study has potential application prospects in the fields of quantum optical devices and quantum information processing.