The formation environment and the evolution of dark soliton with environment parameters are investigated by using the electromagnetically induced transparency effect produced high dispersion and nonlinearity. To improve the stability and operability, a dual-well semiconductor is used. Combining the quantum theory and the classical field theory, we derive the nonlinear Schrodinger equation to describe the formations and evolutions of wave and soliton. It is demonstrated that the dark soliton can form and propagate in the medium when the medium is anomalously dispersive and cross phase modulation is negative simultaneously, and that in the evolution of the soliton, the width, gray scale and phase are related to each other, the smaller the pulse duration, the bigger the gray scale is and the faster the growth is. In addition, the modulation instability of the nonlinear system is analyzed, and the gain spectrum of the nonlinear system is also discussed.
The formation environment and the evolution of dark soliton with environment parameters are investigated by using the electromagnetically induced transparency effect produced high dispersion and nonlinearity. To improve the stability and operability, a dual-well semiconductor is used. Combining the quantum theory and the classical field theory, we derive the nonlinear Schrodinger equation to describe the formations and evolutions of wave and soliton. It is demonstrated that the dark soliton can form and propagate in the medium when the medium is anomalously dispersive and cross phase modulation is negative simultaneously, and that in the evolution of the soliton, the width, gray scale and phase are related to each other, the smaller the pulse duration, the bigger the gray scale is and the faster the growth is. In addition, the modulation instability of the nonlinear system is analyzed, and the gain spectrum of the nonlinear system is also discussed.
Electromagnetically-controlled precision is one of novel topics in the electromagnetics. To realize the precision controlling of the electromagnetically complicated phenomenon, the systematic characteristics of medium environment needs considering. Based on the cancellation of interference caused by quantum coherence in the systematic environment of material, the electromagnetically-induced transparency (EIT) can be achieved. For this nonlinear phenomenon, due to the advancement of quantum spot and well, the controlling of the bounded sate of quantum in various dimensions of semiconductor can be operated. So the solid system presents a clear superiority of controlling EIT. High power electromagnetic field excites the dynamic characteristics in solid material, which is the result of systematic reaction between field and material. Under the excitation of electromagnetic pulse, because of quantum coherence, the dual-well semiconductor has the ability to induce the dark state of solitons. In the study of the complicated system of multiple physical fields, two aspects need investigating further. Firstly, in the induction process of electromagnetic filed and solid material, the features of high dispersion and nonlinear reaction appear increasingly. Thus, due to the environmental restriction on dispersion and nonlinear reaction, electromagnetic dissipation is a crucial point, which needs considering in the electromagnetically-controlled precision of the EIT. Secondly, compared with the formation of soliton, the coupling reaction of solitons under co-sate is much complicated. The relation among these factors is necessary to be investigated in the formulation of soliton excitation. Therefore, a dual-well semiconductor is employed as solid environment to analyze the dynamic characteristics of dark solitons in the EIT. In order to achieve the controlling of precision and regulating of the effect, the environmental features of solid materials ought to be systematically considered. Accordingly, the variational method is utilized, through which the bounded action of dissipation and nonlinear coherence is effectively studied for the dark solitons under co-sate, and under the condition of exciting dark soliton in the system of EIT. Using the density matrix and electric polarization, the spectrum of dynamic transmission deviation of EIT is calculated in the solid environment. With the assistance of relevant action principle, the bounded relation of dark solitons under co-state is practically investigated in the dissipative environment of solid system. In addition, the space-time trajectory is analyzed in the applicable region of characteristic equations of dark solution. The deduced result indicates that the systematical balance between dissipative weakening and coherent coupling supports the valuable approach to controlling the space-time evolution of dark solitons in precision. The results also show that the special effect has the potential applications in electromagnetically-controlled precision in the quantum information, ray sensor, controllable environment, etc.
We have investigated the nonlinear interaction between a weak-pulsed probe field and a four-level Y-type atomic system with dual ladder-type electromagnetically induced transparency. Two strong coupling fields induce a quantum destructive interference effect which depletes the population in the two nearly degenerate uppermost levels of the system and dramatically enhances the linear as well as nonlinear dispersion while simultaneously significantly suppressing the probe field absorption. We present the semiclassical quantum analysis of the system. The perturbation method of multiple scales is used to derive a differential envelope equation that describes the propagation of the probe field in the Y-type atomic system. It is then demonstrated that bright and dark optical solitons can be formed in this system.
Abstract We investigate the speed of temporal dark soliton based on an optical coherent medium. It is demonstrated that the temporal dark soliton is described by a nonlinear Schrodinger equation whose coefficients are decided by the coherent medium. It is found that the speed of temporal dark soliton not only relies on the linear responses including GV parameter, group velocity dispersion parameter as well as the amplitude of dark soliton, but also relies on the nonlinear response like self-phase modulation parameter. Additionally, the dark soliton in anomalous-dispersion regime propagates slower than bright soliton, while in normal-dispersion regime it inversely propagates faster than bright soliton. The complicated property of the speed for dark soliton is quite different from the bright soliton whose speed is commonly only related to the group velocity parameter. We attribute this feature to the modulation instability of the nonlinear system.
In the past few years, with developing the technology of electromagnetically induced transparency (EIT) and improving the semiconductor technology, it has become possible to realize the application of optical soliton to communication device. Studies show the reduction of group velocity of the optical soliton in EIT medium under weak driving condition, which possibly realizes the storing of optical pulses in information storage. More importantly, semiconductor quantum wells have the inherent advantages such as large electric dipole moments of the transitions, high nonlinear optical coefficients, small size, easily operating and integrating. So it is considered to be the most potential EIT medium to realize the application of quantum devices. The optical soliton behavior in the semiconductor quantum well is studied, which can provide a certain reference value for the practical application of information transmission and processing together quantum devices. Although there has been a series of researches on both linear and nonlinear optical properties in semiconductor quantum wells structures, few publications report the effects of the cross-coupling longitude-optical phonon (CCLOP) relaxation on its linear and nonlinear optical properties. However, to our knowledge, the electron-longitude-optical phonon scattering rate can be realized experimentally by varying the sub-picosecond range to the order of a picosecond. According to this, we in the paper study the effects of the CCLOP relaxation on its linear and nonlinear optical properties in a cascade-type three-level EIT semiconductor quantum well. According to the current experimental conditions, we first propose a cascade-type three-level EIT semiconductor quantum well model. And in this model we consider the longitudinal optical phonons coupling between the bond state and anti-bond state. Subsequently, by using the multiple-scale method, we analytically study the dynamical properties of solitons in the cascade-type three-level EIT semiconductor quantum well with the CCRLOP. It is shown that when the CCRLOP strength is smaller, there exhibits the dark soliton in the EIT semiconductor quantum well. Only if the strength of the CCRLOP is larger, will in the system there exists bright soliton. That is to say, with increasing the strength of the CCRLOP, the soliton type of the system is converted from dark to bright soliton little by little. So, the temporal soliton type can be effectively controlled by the strength of the CCRLOP. In addition, we also find that the group velocity of the soliton can also be controlled by the strength of CCRLOP and the control light. These results may provide a theoretical basis for manipulating experimentally the dynamics of soliton in semiconductor quantum wells.
In this paper, we present the dynamics of supercontinuum (SC) generation in an asymmetric semiconductor quantum well (SQW) system employing modulated nonlinearity and dispersion under an electromagnetically induced transparency (EIT) window. Specifically, we utilize a weak probe pulse in the system, which is modulated by a strong control field, exploiting the phenomenon of EIT. Adjusting the control field parameters, we obtain large nonlinearities of the order [Formula: see text] and [Formula: see text] at probe wavelengths [Formula: see text] and [Formula: see text], respectively. The corresponding dispersion values are [Formula: see text] (for anomalous dispersion) and [Formula: see text] (for normal dispersion), respectively. We investigate the generation of a supercontinuum in the system separately for both the dispersion regimes by using a narrow-band Gaussian pulse. In the regime of anomalous dispersion, the broadening of the SC is mainly governed by the nonlinear processes like the self-phase modulation (SPM), the dispersive wave emission and the soliton self-frequency shift. These nonlinearities manifest into a highly modulated spectral profile with a span of around four octaves ([Formula: see text]3–11.5[Formula: see text][Formula: see text]m). However, in the domain of normal dispersion, the SC is dominated by SPM, extending asymmetrically to the higher wavelength side owing to the third-order dispersion. This results in the formation of a smooth and practically flat spectrum, but with a reduced bandwidth of around 3[Formula: see text][Formula: see text]m. Our study highlights the versatility of EIT-assisted nonlinear optical control in SQW systems and refers to their possible use in the development of broadband light sources for spectroscopy, optical communications and the development of integrated photonic devices.
By using multiple-scale method，we analytically study the nonlinear dynamical properties of an electromagnetically induced transparency medium with three-level atoms and a strong coupling light field. It is shown that a weak probe light beam can form spatial weak-light dark solitons. When it propagates along axial direction，the dark soliton will transforms into a steady spatial weak-light ring dark soliton，which results from the balance of the interplay between beam diffraction and refractive nonlinearity.