We investigate the optical response properties of an atom-assisted spinning optomechanical system, in which a spinning optical resonator is coupled simultaneously to a two-level atomic ensemble and a mechanical resonator driven by a weak pump field. Remarkably, we demonstrate that by simply reversing the rotation direction, the system can be switched between a low-absorption electromagnetic and optomechanically induced transparency state and a high-absorption state, constituting a form of non-reciprocal optical control at the quantum level. Furthermore, by tuning the phase difference between the mechanical pump and the probe field, direction-dependent switching between absorption and gain is achieved. These non-reciprocal effects originate from the Sagnac-induced frequency shift in the optical mode, which leads to distinct optomechanical and atom-cavity couplings for opposite spinning directions. We also show that the absorption spectrum can be modulated by the angular velocity and the atomic number. Our results indicate that the optical properties of the hybrid system can be manipulated via the angular velocity, phase difference, and atom number, with potential applications in chiral photonic communications.
We investigate the optical response properties of an atom-assisted spinning optomechanical system, in which a spinning optical resonator is coupled simultaneously to a two-level atomic ensemble and a mechanical resonator driven by a weak pump field. Remarkably, we demonstrate that by simply reversing the rotation direction, the system can be switched between a low-absorption electromagnetic and optomechanically induced transparency state and a high-absorption state, constituting a form of non-reciprocal optical control at the quantum level. Furthermore, by tuning the phase difference between the mechanical pump and the probe field, direction-dependent switching between absorption and gain is achieved. These non-reciprocal effects originate from the Sagnac-induced frequency shift in the optical mode, which leads to distinct optomechanical and atom-cavity couplings for opposite spinning directions. We also show that the absorption spectrum can be modulated by the angular velocity and the atomic number. Our results indicate that the optical properties of the hybrid system can be manipulated via the angular velocity, phase difference, and atom number, with potential applications in chiral photonic communications.
Abstract We investigate the optical-response properties of a coherent-mechanical pumped optomechanical system (OMS) coupled to a Λ-type three-level atomic ensemble. Due to the optomechanical and the cavity-atom couplings, the optomechanically induced transparency (OMIT) and electromagnetically induced transparency (EIT) phenomena could both be observed from our proposal. In the presence of a coherent mechanical pump, we show that the OMIT behavior of the probe field exhibits a phase-dependent effect, leading to the switch from OMIT to optomechanically induced absorption or amplification, while the feature of EIT remains unchanged. The distinctly different effects of the mechanical pump on OMIT and EIT behavior assure us that the absorption (amplification) and transparency of the output probe field can be simultaneously observed. Moreover, a tunable switch from slow to fast light can also be realized by tuning the phase and amplitude of the mechanical pump. In particular, the presence of the atomic ensemble can further adjust the group delay, providing additional flexibility for achieving the tunable switch.
Abstract We study the pump-probe response in an optomechanical cavity accommodating an ensemble of two-level atoms interacting with a cavity mode, which is pumped by a strong driving field and probed by a weak signal field. The atomic excitation is examined without taking any approximations and may be in any regimes ranging from the low limit to the high limit for a given collective coupling constant between the atomic ensemble and the cavity mode. This then results in different absorption and dispersion spectra (such as optomechanically induced transparency, Fano-resonance, normal-mode splitting) when the excitation transfer from cavity mode to atomic ensemble is controlled to change from ineffective to effective. This indicates that a hybrid optomechanical response is indeed determined by the excitation of the atomic ensemble embedded in the optomechanical cavity. It is also of interest that the output signal component and the inside atomic polarization show either synchronous or asynchronous behaviors depending on how the atom-field detuning is chosen, i.e. equal to the mechanical resonator frequency or its negative. Such features may open up an effective avenue in coherently manipulating the internal atomic polarization via the external signal field, and vice versa.
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 the reflected and transmitted output properties of a weak probe field incident upon an optomechanical cavity separated by a membrane oscillator and filled with two-level cold atoms. We find that electromagnetically induced transparency (EIT) and optomechanically induced transparency (OMIT) may simultaneously exist owing to separate cavity–atom coupling and cavity-oscillator coupling, respectively. It is more interesting that the hybrid EIT and OMIT phenomena can be manipulated on demand to exhibit various spectral features on dispersion, transmission, and reflection. In particular, we discover the new hybrid double transparency window (a narrow OMIT dip appearing inside the wide EIT window), analogous to double EIT for a four-level atomic system in inverted-Y configuration. Meanwhile, we can reduce the hybrid EIT–OMIT to a single EIT or OMIT shape by changing the magnitude of the driving field power or the atomic number as desired. Furthermore, by changing the system’s detuning it is possible to change the location and the profile of the EIT, therefore switching the shape of the hybrid EIT–OMIT from symmetric to asymmetric, as well as for the profile to change from a absorption dip-like EIT to dispersion-like EIT in both real and imaginary parts of the output probe field. Also, by modifying system’s detuning we have control over the distribution of the output energy, something difficult to achieve with only one of the sub-systems available.
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 .
Abstract Optomechanics has become a very active area of research in recent years and has attracted significant interest in both theoretical and experimental studies. In this work, we theoretically investigate optomechanically induced transparency (OMIT) using a hybrid system consisting of two coupled optical cavities, each interacting with a spin ensemble. The cavities are coherently driven by a strong control field and a weak probe field. We analytically calculate the transmission spectrum of the coupled spin–cavity system and analyze the dynamics of the system. The obtained transmission response shows clear signatures of multi-window OMIT, which arises from coherent interference between the hybridized normal modes. Our results indicate that the presence of spin ensembles in both cavities significantly enhances the transparency behavior and provides additional tunable parameters to control the OMIT windows. In particular, the transmission spectrum and the shape of the transparency profile can be controlled by the spin–cavity interaction and the inter-cavity coupling strength J . Furthermore, the inter-cavity tunneling rate, spin decoherence, and spin–cavity coupling strength strongly influence the transparency properties. Overall, this study highlights the potential of spin-based multi-cavity optomechanical systems for coherent optical control and tunable quantum interference.