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.
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.
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.
We study the four-wave mixing (FWM) effect in a hybrid atom-optomechanical system, which is composed of an ensemble of two-level atoms trapped inside an optical cavity and a moveable cavity mirror serving as a mechanical resonator. It is shown that the FWM signal in this hybrid system can be significantly enhanced due to the coupling between the optical cavity and the atom ensemble. The larger the atom-cavity coupling strength is, the stronger the FWM will be. More interestingly, the FWM signal can be effectively modulated by the atom-pump detuning. It is demonstrated that, just by tuning this detuning to be positive or negative, the FWM signal can be easily switched on or off for the zero probe-pump detuning case. The obtained results may have potential applications in all-optical wavelength convertors, all-optical switches, or other optical devices.
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 The various properties of the output spectrum for a probe field in a hybrid optomechanical system that is composed of two cavities, each containing an atomic ensemble and a mechanical resonator, is analyzed. Also, the normal‐mode splitting behaviors induced by the interactions between subsystems in detail are discussed and their respective effects are clarified. The interpretations for the linear variation of the separation between two absorption peaks is given out. In the available parameter regime, three tunnel coupling critical points, which describe the transition behaviors between absorption and amplification, are determined. Based on the first critical point, the influence of the two‐level atomic ensemble on absorption (amplification) effect is studied. The effect of the two‐level atomic ensemble not only splits the absorption peak (amplification dip), but also realizes the enhancement of the absorption (amplification) effect and the transformation between absorption and amplification effects. Meanwhile, the one‐to‐one correspondence location relations between the transparency dip and absorption peak for the double optomechanically induced transparency‐like and optomechanically induced absorption‐like, respectively, are also investigated. With a multi‐level atomic ensemble, the multi‐transparency (absorption) effect is realized readily. These rich spectrum properties of the probe field may benefit forward achieving of the optical switch in experiment and possible applications in coherent control of light pulses.
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 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.