Cooperative Radiation And Phase Correlation In Semiconductor Microcavity Systems

Based on various kinds of interactive mechanisms,the cooperative behavior among the particles in a many-body system and the correlation among several multibody systems have always been a fundamental and important issue in physics.Such as the atom gas at very low temperature,by means of the interaction among the particles,could form a Bose-Einstein condensate.In contrast,the exciton-polariton,composed by the strong coupling between exciton and photon in solid materials,has much lower effective mass than atoms,which could form the exciton-polariton condensate at a higher temperature.Meanwhile,the correlation behavior among multiple condensates has also been confirmed by quite a lot of works.However,most of the previous experiments about coherence and collective behavior in solid system were achieved by the conditions below the Mott transition.In the high temperature and high density region,corresponding to plasma phase,it is generally considered the longrange correlation will not be established due to the drastic scattering dephasing.Thus,how to produce the cooperative effect in this region and even establish the correlation among several plasmas are still an important but challenging research direction.In our work,by using a designed semiconductor microcavity,the long-range correlation and cooperative radiaition are achieved in the electron-hole plasma.On this basis,throught the optical coupling induced by the superfluorescence,two droplets of electron-hole plasma could establish a cross-regional phase correlation,which successfully extends the collective behavior and multibody correlation of electron-holephoton system to the high temperature and high density region in the phase diagram.When the excitation density exceeds the threshold,the electron-hole plasma will trigger a cooperative radiation.This radiation will be enhanced through the stimulated amplification process in microcavity and form a cavity-enhanced superfluorescence.As a result,the high density electron-hole-photon system will demonstrate macroscopic coherence and show condensation behavior at room temperature.Furthermore,with the aid of the microcavity,two such light-matter systems could establish a long-range and stable phase correlation by exchanging their radiation field even though their distance is much larger than the characteristic optical wavelength.Experimental results show that correlative phase difference between the two droplets have multiple correlation modes and exhibits a quantization switching behavior in the photoluminescence process.In addition,the phase correlation can be modulated by varying the excitation density and the distance between the two excitation regions.In the formation process about the above phenomena,the cavity-enhenced superfluorescence plays a decisive role.In order to study this radiaton form further,the influences of particle density,dephasing time and photon lifetime on the cooperative radiation of a dipole ensemble are analyzed by theoretical calculation.It finds that as increasing of the dipole density and the lifetime of the cavity photons,the photoluminescence will have a stronger intensity and shorter duration time.Decreasing the dipole dephasing also has the similar results.It makes the system present different radiation forms.Hereby,the differences and connections among spontaneous emssion,common laser,superfluorescence,cavity-enhanced superfluorescence and oscillatory cavity-enhanced superfluorescence could be domestrate on the phase diagram visibly.It complements and enriches the physics picture of interactive system between light and dipole ensemble.The cavity-enhanced superfluorescence,with the characteristic of high intensity,short pulse and narrow linewidth,could be used in the manufacture about the high performance quantum light source or in the high-speed,high-bandwidth laser communication.Through the superfluorescence or the cavity-enhanced superfluorescence process,the coherence of the material component is proved to have quick response ability and be convenient for adjustment.It has widely application prospects in scientific research and the development of ultrafast quantum photoelectric devices.