Atomically thin two-dimensional semiconductor nanomaterials have attained considerable attention currently. We here theoretically investigate the phenomena of slow and superluminal light based on the MoS 2 resonator system driven by two-tone fields. Superluminal and ultraslow probe light without absorption can be obtained via manipulating the pump laser on- and off-resonant with the exciton frequency under different parameters regimes, respectively, of which the magnitude is larger than that in a carbon nanotube resonator. The bandwidth of the probe spectrum determined by the quality factor Q of MoS 2 resonator is also presented. Furthermore, we also demonstrate the phenomenon of phonon induced transparency and show an optical transistor in the system. The all-optical device based on MoS 2 resonator may indicate potential chip-scale applications in quantum information with the currently popular pump-probe technology.
Atomically thin two-dimensional semiconductor nanomaterials have attained considerable attention currently. We here theoretically investigate the phenomena of slow and superluminal light based on the MoS 2 resonator system driven by two-tone fields. Superluminal and ultraslow probe light without absorption can be obtained via manipulating the pump laser on- and off-resonant with the exciton frequency under different parameters regimes, respectively, of which the magnitude is larger than that in a carbon nanotube resonator. The bandwidth of the probe spectrum determined by the quality factor Q of MoS 2 resonator is also presented. Furthermore, we also demonstrate the phenomenon of phonon induced transparency and show an optical transistor in the system. The all-optical device based on MoS 2 resonator may indicate potential chip-scale applications in quantum information with the currently popular pump-probe technology.
We report a tunable slow and fast light device based on a carbon nanotube resonator, in the presence of a strong pump laser and a weak signal laser. Detailed analysis shows that the signal laser displays the superluminal and ultraslow light characteristics via passing through a suspended carbon nanotube resonator, while the incident pump laser is on- and off-resonant with the exciton frequency, respectively. In particular, the fast and slow light correspond to the negative and positive dispersion, respectively, associating with the vanished absorption. The bandwidth of the signal spectrum is determined by the vibration decay rate of carbon nanotube.
We theoretically study the coherent interaction of a tripod-type atomic system with three laser fields, i.e., one probe and two coupling, or two probe and one coupling field. Our analytical and numerical results show that, when all three fields are on two-photon resonance, in addition to the Rabi frequencies of the coupling fields, the probe group velocities also depend on the spontaneous decay rates and the initial population distribution. So we can manipulate the probe pulses to achieve controllable ultraslow group velocities by preparing different initial atomic states. With an incoherent pump field applied, a narrow transparent window accompanied by abnormal dispersion may occur in the probe absorption spectrum, which then allows us to switch a probe pulse from ultraslow to superluminal propagation.
In recent years, due to the rapid development of nano science and advanced semiconductor technology, one is able to observe more significant quantum optomechanical effects as optomechanical system turns smaller in size. Optomechanically induced transparency, fast and slow light, optical storage as well as other quantum optical and nonlinear optical effects have become the focus of research. On the other hand, the optomechanical systems coupled to other small subsystems (such as atoms, quantum dots, single electron transistors, etc.) also attract great attention in research. This is because the coupling system has not only provided more degrees of freedom for quantum manipulation, but also opened up more channels for classical and quantum information transfer. In this paper we study the optomechanically induced transparency and fast/slow light phase control in atom-assisted optomechanical cavity. Unlike the traditional systems, in this model the mechanical resonator is directly driven by a weak auxiliary driving field. We therefore find that with the change of amplitude ratio and phase difference between the auxiliary driving field and the probe field, the absorption and dispersion properties of the whole system and the group delay time vary accordingly. In the absence of auxiliary field, we observe the spectral features of the hybrid electromagnetically induced transparency and optomechanically induced transparency (OMIT) in an atom-cavity-oscillator tripartite optomechanical system. When there exists no phase difference between the auxiliary field and the probe field, we find that the membrane resonance absorption is enhanced with the increase of auxiliary field strength at resonance, causing the the optomechanically induced transparency to be suppressed, and therefore we can modify the amplitude of auxiliary field to control the depth of the OMIT window. When keeping amplitude ratio between the auxiliary field and the probe field unchanged, the modification of the phase difference between the auxiliary field and the probe field directly affects the we can not only realize the manipulation of OMIT window depth, but also control the transformation of tunable optical switch among "absorption", "transparent" and "gain" of the system. Therefore, through changing the phase of auxiliary field and probe field, we can not only realize the manipulation of OMIT window depth, but also control the transformation of tunable optical switch among "absorption" , "transparent" and "gain". In the meantime, we find that the system’s group delay time varies periodically with the change of phase difference. It is worth noting that by adjusting the phase difference and the atomic number, we can not only change the magnitude of the group delay, but also realize the conversion between slow light and fast light effect.
Abstract We study a two-cavity optomechanical system in which one cavity ( A ) encloses a mechanical resonator and the other cavity ( C ) encloses a two-level atom are, respectively, driven by a strong pump and a weak probe fields. In addition to a direct pathway, the excitations in cavity C and the enclosed atom can also be caused through an indirect pathway. The interference between the two possible routs for excitations produces a controllable transparency window in the probe transmission spectrum of cavity C . The coupling strength between cavity C and the atom works as an additional parameter to the coupling strength between the two cavities which helps to manipulate the dynamical properties of the system and hence to control the width of the transparency window. Furthermore, we show that the single setup can be used to produce an optical switch from two different physical behaviors of the model, and to realize subluminal and superluminal behaviors in the output spectrum at probe frequency of cavity C .
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.
We theoretically propose a loop-coupled multimode optomechanical system (OMS) with a single-mode cavity, a two-level system (TLS), and a mechanical resonator, which are coupled to each other. With controlled coupling parameters, the loop-coupled multimode OMS can flexibly transform into different OMSs (e.g. cavity OMSs, cavity quantum electrodynamic systems). By simultaneously driving the single-mode cavity using pump and probe fields, we investigate the coherent optical response and transmission spectra for the transparent window and absorption dips. Additionally, the transparent window and absorption dips that induce coherent light propagation were demonstrated. Our findings demonstrate that the transparent window and absorption dips can generate slow (fast) light, and that the control of coupling parameters can modulate optical fields in different OMSs. With further weaving of these coupling parameters, the loop-coupled multimode OMS can be a quantum information processing platform for chip-scale applications.