Abstract We propose and analyze an effective scheme to enhance Kerr nonlinearity with a single quantum dot (QD) coupled to a gain cavity. Under the weak-excitation approximation, we derive the analytic formulas used to determine the coefficient of the nonlinear transmission by employing the perturbation technique. Using experimentally achievable parameters, we identify the conditions under which a QD gain cavity coupled system allows us to modify the linear transmission of the input probe field and enhance the Kerr nonlinearity beyond what is achievable in a QD loss cavity system. It is found that enhanced optical Kerr nonlinearity with high linear transmission rate and suppressed nonlinear absorption can be achievable even in the case of weak coupling between QD and gain cavity. The present results illustrate the potential to utilize gain cavity for enhancing optical Kerr nonlinearities and controlling the transmission of light, as well as guide the design of optical devices.
Abstract We propose and analyze an effective scheme to enhance Kerr nonlinearity with a single quantum dot (QD) coupled to a gain cavity. Under the weak-excitation approximation, we derive the analytic formulas used to determine the coefficient of the nonlinear transmission by employing the perturbation technique. Using experimentally achievable parameters, we identify the conditions under which a QD gain cavity coupled system allows us to modify the linear transmission of the input probe field and enhance the Kerr nonlinearity beyond what is achievable in a QD loss cavity system. It is found that enhanced optical Kerr nonlinearity with high linear transmission rate and suppressed nonlinear absorption can be achievable even in the case of weak coupling between QD and gain cavity. The present results illustrate the potential to utilize gain cavity for enhancing optical Kerr nonlinearities and controlling the transmission of light, as well as guide the design of optical devices.
Achieving strong optical nonlinearity in a low excitation power level is crucial in micro- and nanophotonics, central to many applications. Here, we explore optical linear and nonlinear responses in a single quantum dot (QD) embedded into a single-mode cavity under the effect of an external magnetic field and a continuous-wave laser excitation in the weak-coupling regime. Using experimentally realistic parameters, we find that the magnetic field introduced in such a coupled cavity-QD system can drastically modify the properties of photons and thus can be employed as a flexible control parameter. Especially, the enhanced optical Kerr nonlinearity can be achieved by tuning the applied magnetic field appropriately, which can reach over 11-fold improvement as compared to the case without the magnetic field. Physically, this is the consequence of the magnetic-field-induced resonance shifts and the cavity-field-mediated interferences. As an example of its applications, in the basis of this attainable strong Kerr nonlinearity, we show a feasible way of generating an optical high-order sideband efficiently, with small sideband spacing, as small as a few tens of megahertz, and low input excitation power, as low as a few nanowatts. Moreover, the manipulation of the high-order sideband is also discussed by changing the magnetic field from 0 to 3 T, where the variation of the sideband power is in good agreement with that of the Kerr nonlinearity. Considering realistic experimental conditions we elaborate the possible implementation of our proposal. In addition to being of fundamental interest, the results of our paper hold potential in optical frequency combs, nonlinear optics, and high precision measurement.
We theoretically investigate optical bistability and entanglement in a hybrid nonlinear system of two coupled cavities via a single-mode waveguide. The left cavity contains an ensemble of N quantum dots (QDs) and a Kerr medium to enhance the nonlinearity as it causes to observe the bistable behaviour of the system. We study the Kerr medium, QD ensemble, and cavity coupling effect on bistability response shown by mean intracavity photons in the left cavity. In addition, we have shown entanglement between different subsystems and found that entanglement can be generated between the two coupled cavity photons, cavity photons, and QD ensembles. Additionally, we investigate the effect of different parameters on entanglement. Our findings show that Kerr nonlinearity and the hopping parameter between the two cavities can effectively control the optical properties of the proposed hybrid system, which can be used to design efficient optical devices and the entangled optical photons have applications such as quantum information transfer.
Abstract This paper presents the dynamics of Kerr nonlinearity and the phenomenon of slow group velocity in a Quantum Dot (QD) system, using the mechanism of electromagnetically induced transparency (EIT). Employing a three-level QD setup and leveraging a ladder-type excitation approach, we analyse the interaction between a weak probe pulse and a strong control beam. By employing density matrix formalism, we derive the expressions for both linear and nonlinear optical susceptibilities, along with first-order linear dispersion terms. Our findings reveal that susceptibilities in the QD system, both linear and nonlinear, can be finely adjusted to desired probe frequencies through control parameter manipulation. Moreover, under the EIT regime, we observe the Kerr susceptibility on the order of 10−12 m2 V2 at a probe wavelength 1.359 μm. Additionally, the group velocity of the probe field experiences a remarkable slowdown by a factor of 103 compared to the speed of light in vacuum. Results obtained may have potential applications in fabricating nonlinear optical devices.
Abstract An efficient scheme for probing electron tunnelling is proposed based on the enhanced cross-Kerr nonlinearity in a double–dot system. Due to resonant tunnelling, the cross-Kerr nonlinearity arises in a transparency window. Its intensity is nearly two orders of magnitude greater than that of the self-Kerr effect under any given conditions, where residual absorption is suppressed due to the competition of nonlinear gain and absorption. The enhanced cross-Kerr effect is sensitive to the tunnelling, so the probe spectrum can detect subtle tunnelling changes. The simulation results show that the probe sensitivity of the nonlinear phase shift is about 0.28 rad/ μ eV.
We represent an optical scheme using cross-Kerr nonlinearities (XKNLs) and quantum dot (QD) within a single-sided optical cavity (QD-cavity system) to generate three-photon entangled W state containing entanglement against loss of one photon of them. To generate W state (three-photon) with robust entanglement against loss of one photon, we utilize effects of optical nonlinearities in XKNLs (as quantum controlled operations) and QD-cavity system (as a parity operation) with linearly optical devices. In our scheme, the nonlinear (XKNL) gate consists of weak XKNLs, quantum bus beams, and photon-number-resolving measurement to realize controlled-unitary gate between two photons while another nonlinear (QD) gate employs interactions of photons and an electron of QD confined within a single-sided optical cavity for implementation of parity gate. Subsequently, for the efficiency and experimental feasibility of our scheme generating W state, we analyze the immunity of the controlled-unitary gate using XKNLs against decoherence effect and reliable performance of parity gate using QD-cavity system.
Considering the exciton-biexciton coherence, we analytically study the linear absorption and nonlinear propagation properties of the probe and signal field in a semiconductor quantum dot. It is found that in the linear case, in the system takes place an electromagnetically induced transparency phenomenon. Furthermore, we obtain that in the system there occurs one- or two-transparency window, or optical gain, which is controlled by adjusting the coupling control field. For the nonlinear case, the weak probe field, which is induced by a signal field, splits into two parts. When their excited self-Kerr and cross-Kerr nonlinear effects balance the refractive effect of the beam, the system exhibits bright-bright, bright-dark, dark-bright, dark-dark soliton pairs.