The generation of second-order sidebands and its associated group delay is an important subject in optical storage and switch. In this work, the efficiency of second-order sideband generation in a coupled optomechanical cavity system with a cubic nonlinear harmonic oscillator is theoretically investigated. It is found that the efficiency of second-order sideband generation can be effectively enhanced with the decrease in decay rate of optomechanical cavity, the increase in coupling strength between two cavities and the power of probe field. The slow light effect (i.e., positive group delay) is also observed in the proposed optomechanical cavity system, and can be controlled with the power of control field.
The generation of second-order sidebands and its associated group delay is an important subject in optical storage and switch. In this work, the efficiency of second-order sideband generation in a coupled optomechanical cavity system with a cubic nonlinear harmonic oscillator is theoretically investigated. It is found that the efficiency of second-order sideband generation can be effectively enhanced with the decrease in decay rate of optomechanical cavity, the increase in coupling strength between two cavities and the power of probe field. The slow light effect (i.e., positive group delay) is also observed in the proposed optomechanical cavity system, and can be controlled with the power of control field.
Second-order sideband generation (SSG) is investigated in an optomechanical system with atom-cavity-resonator coupling. We focus mainly on the effect of the atomic ensemble trapped in the cavity on the SSG. The numerical results show that the second-order sideband is induced not only for the blue probe-pump detuning resonant case but also for the red one while coupling the atoms with the cavity. Moreover, it is found that the efficiency of the SSG can be significantly enhanced while increasing the atom-cavity coupling strength. More interestingly, the SSG is also sensitive to the atom-pump detuning. It is demonstrated that when optimizing this detuning and the atom-cavity coupling strength together, a robust second-order sideband can be induced and the efficiency of the SSG even surpasses the one of the first-order sideband generation. In addition, the efficiency of the SSG can also be tuned effectively by the decay rate of the atom.
Cavity magnomechanics (CMM) has rapidly become a new research field of cavity quantum electrodynamics for studying quantum information processing and sensing. Here, we theoretically study the magnomechanically induced transparency effect in a cavity magnomechanical system, focusing on the role of magnon squeezing in enhancing and controlling the group delay of the transmitted light. As a result, we find that the magnon number can be strongly affected by magnon squeezing, accompanied by a steerable transmission rate and controllable fast-to-slow light switching. In particular, in the photon-magnon strong-coupling scenario, the group delay of the probe field can be enhanced by about three times by using magnon squeezing compared to the case without magnon squeezing. Moreover, due to the presence of magnon squeezing, the efficiency of the second-order sideband in the photon-magnon weak-coupling scenario can also be enhanced compared to the case without magnon squeezing. These results provide tools to engineer CMM devices with magnon squeezing for, e.g., light propagation and storage, and precision measurements of weak signals.
We propose an efficient scheme to enhance the generation of optical second-order sidebands (OSSs) in an atom-assisted optomechanical system. The cavity field is coupled with a strong driving field and a weak probe field, and a control field is applied to the atom. We use the steady-state method to analyze the nonlinear interaction in the system, which is different from the traditional linear analysis method. The existence of an auxiliary three-level atom driven by the control field significantly enhances the generation of an OSS. It is found that the efficiency of the OSS can be effectively modulated by adjusting the Rabi frequency of the control field, optomechanical cooperativity and atomic coupling strength. Our scheme provides a promising solution for controlling light propagation and has potential application in quantum optical devices and quantum information networks.
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.
It is quite important to enhance and control the optomechanically induced high-order sideband generation to achieve low-power optical comb and high-sensitivity sensing with an integrable structure. Here we present and analyze a proposal for enhancement and manipulation of optical nonlinearity and high-order sideband generation in a hybrid atom-cavity optomechanical system that is coherently driven by a bichromatic input field consisting of a control field and a probe field and that works beyond the perturbative regime. Our numerical analysis with experimentally achievable parameters confirms that robust high-order sideband generation and typical spectral structures with nonperturbative features can be created even under weak driven fields. The dependence of the high-order sideband generation on the atomic parameters are also discussed in detail, including the decay rate of the atoms and the coupling parameter between the atoms and the cavity field. We show that the cutoff order as well as the amplitude of the higher-order sidebands can be well tuned by the atomic coupling strength and the atomic decay rate. The proposed mechanism of enhancing optical nonlinearity is quite general and can be adopted to optomechanical systems with different types of cavity.
We study the gain-enhanced nonlinear optomechanically-induced trans- parency (OMIT). We find that (i) for a single cavity, significant enhancement can be achieved for gain-assisted higher-order sidebands, including the transmission rate and the group delay; (ii) for active-passive-coupled cavities, in the vicinity of the gain-loss balance, hundreds of microsecond of relative delay or advance are attainable between the probe and the nonlinear sideband pulses. The gain-enhanced higher-order OMIT effects, as firstly revealed here, indicate the possibility to make a two-color modulator, which can control both the strength and group delay of not only the probe light but also its higher-order sidebands.