量子点腔非谐振耦合系统纯退相干的特性及应用

Characteristics of Pure Dephasing on Non-resonant Quantum Dot-cavity Coupling System and its Application Prospect

采用非相干泵浦、受激辐射和纯退相干的量子主方程研究了量子点腔耦合系统,得出腔与量子点发射光谱解析解.理论分析显示,在非谐振耦合系统中纯退相干能使腔发射谱产生明显的移位效应,从而可以解释"非谐振耦合腔有效发射"效应.为了进一步研究纯退相干在量子点腔耦合系统上的应用,引入了系统有效耦合率和单光子源效率,并通过比较有效耦合率与腔耗散定义出好腔与坏腔机制.选取两组依据实验数据作为参量,在共振与失谐时研究了纯退相干对系统有效耦合率和单光子源效率的影响.结果表明:纯退相干可提高失谐系统有效耦合率与单光子源效率,从而可能使坏腔转变为好腔;两组参量中有较大耦合效率一组在一定范围内满足好腔机制,其单光子源效率明显优于另一组.在非谐振耦合系统比较了好腔机制与坏腔机制的激光,好腔机制是实现单量子点激光的必要条件;由于非谐振耦合系统Fano因子无最大值出现,从而该系统可能无激光阈值.

The quantum dot-cavity system was investigated using a quantum master equation that took incoherent pumping,stimulated emission and pure dephasing into consideration,and analytical emission spectra at cavity and dot were presented.The theoretical analysis results show that the pure dephasing shifts the emission intensity towards the cavity frequency in non-resonant coupling system and thus can be a very good explanation of the non-resonantly coupled cavity effective emission effect.In order to further study the application of pure dephasing in the quantum dot-cavity coupled systems,the effective quantum dot-cavity coupling rate and the efficiency of the single photon source for detuned systems were introduced,and good cavity and bad ragime were able to be defined through comparing the effective quantum dot-cavity coupling rate and the cavity decay rate.Influence of the pure dephasing on the efective coupling rate and the efficiency of the single photon source were investigated in resonance and detuning selected two set of theoretical parameters according to the experimental data.The results show that the pure dephasing can increase the efftive quantum dot-cavity coupling and the efficiency of single photon source for detuned system and thus may make a transition from bad cavity to good cavity ragime;a set of parameters having larger coupling efficiency in a certain range can meet good cavity ragime that its single photon sources efficiency is obviously better than the other set.Compared with bad cavity regime laser in non-resonant coupling system,the good cavity regime is a necessary condition to achieve single quantum dot lasers;the Fano function shows no evidence of a maximum in the non-resonant coupling system and thus there is no laser threshold in this system.