Chamoli Sandeep Kumar, ElKabbash Mohamed, Zhang Jihua, Guo Chunlei
Opt Lett. 2020 Apr 1;45(7):1671-1674. doi: 10.1364/OL.385844.
We numerically investigate the dynamic control over the spontaneous emission rate of quantum emitters using tunable hyperbolic metamaterials (HMMs). The dispersion of a metal-dielectric thin-film stack at a given frequency can undergo a topological transition from an elliptical to a hyperbolic dispersion by incorporating a tunable metal or dielectric film in the HMM. This transition modifies the local density of optical states of the emitter and, hence, its emission rate. In the visible range, we use an HMM consisting of TiN and ${{\rm Sb}_2}{{\rm S}_3}$SbS and show considerable tunability in the Purcell enhancement and quantum efficiency as ${{\rm Sb}_2}{{\rm S}_3}$SbS phase changes from amorphous to crystalline. Similarly, we show tunable Purcell enhancement in the telecommunication wavelength range using a ${\rm TiN}/{{\rm VO}_2}$TiN/VO- HMM. Finally, tunable spontaneous emission rate in the mid-IR range is obtained using a ${\rm graphene}/{\rm MgF}_2$graphene/MgF HMM by modifying the graphene conductivity through changing its chemical potential. We show that using a metal nitride (for the visible and NIR HMMs) and a fluoride (for the mid-IR HMM) is important to get an appreciable change in the effective permittivity of the thin-film multilayer stack.
我们利用可调谐双曲线型超材料（HMM）对量子发射器的自发发射率进行了数值研究。通过在HMM中加入可调谐金属或介电薄膜，金属 - 介电薄膜堆叠在给定频率下的色散可以经历从椭圆色散到双曲线色散的拓扑转变。这种转变改变了发射器的光学态局域密度，从而改变了其发射率。在可见光范围内，我们使用由TiN和${{\rm Sb}_2}{{\rm S}_3}$SbS组成的HMM，并展示了随着${{\rm Sb}_2}{{\rm S}_3}$SbS从非晶态转变为晶态，珀塞尔增强和量子效率方面有显著的可调谐性。同样，我们使用${\rm TiN}/{{\rm VO}_2}$TiN/VO - HMM在电信波长范围内展示了可调谐的珀塞尔增强。最后，通过改变石墨烯的化学势来改变其电导率，使用${\rm graphene}/{\rm MgF}_2$graphene/MgF HMM在中红外范围内获得了可调谐的自发发射率。我们表明，使用金属氮化物（用于可见光和近红外HMM）和氟化物（用于中红外HMM）对于使薄膜多层堆叠的有效介电常数有明显变化很重要。
