Title: Enhancing Near-Field Radiative Heat Transfer between Dissimilar Dielectric Media by Coupling Surface Phonon Polaritons to Graphenes Plasmons Show Chinese title

Title: 通过将表面声子极化激元耦合到石墨烯等离激元来增强不同电介质介质之间的近场辐射传热

Abstract: Dielectric media are very promising for near-field radiative heat transfer (NFRHT) applications as these materials can thermally emit surface phonon polaritons (SPhPs) resulting in large and quasi-monochromatic heat fluxes. Near-field radiative heat flux between dissimilar dielectric media is much smaller than that between similar dielectric media and is also not quasi-monochromatic. This is due to the mismatch of the SPhP frequencies of the two heat-exchanging dielectric media. Here, we experimentally demonstrate that NFRHT between dissimilar dielectric media increases substantially when a graphene sheet is deposited on the medium with the smaller SPhP frequency. An enhancement of 2.7 to 3.2 folds is measured for the heat flux between SiC and LiF separated by a vacuum gap of size 100 to 140 nm when LiF is covered by a graphene sheet. This enhancement is due to the coupling of SPhPs and surface plasmon polaritons (SPPs). The SPPs of graphene are coupled to the SPhPs of LiF resulting in coupled SPhP-SPPs with a dispersion branch monotonically increasing with the wavevector. This monotonically increasing branch of dispersion relation intersects the dispersion branch of the SPhPs of SiC causing the coupling of the surface modes across the vacuum gap, which resonantly increases the heat flux at the SPhP frequency of SiC. This surface phonon-plasmon coupling also makes NFRHT quasi-monochromatic, which is highly desired for applications such as near-field thermophotovoltaics and thermophotonics. This study experimentally demonstrates that graphene is a very promising material for tuning the magnitude and spectrum of NFRHT between dissimilar dielectric media. Show Chinese abstract

Abstract: 介电介质在近场辐射传热(NFRHT)应用中非常有前景，因为这些材料可以热发射表面声子极化激元(SPhPs)，从而产生大且准单色的热通量。不同介电介质之间的近场辐射热通量比相同介电介质之间的要小得多，并且也不准单色。这是由于两种热交换介电介质的SPhP频率不匹配。在这里，我们实验上证明，当石墨烯片沉积在具有较小SPhP频率的介质上时，不同介电介质之间的NFRHT显著增加。当SiC和LiF之间由100到140纳米的真空间隙隔开，并且LiF被石墨烯片覆盖时，测得的热通量增强了2.7到3.2倍。这种增强是由于SPhPs和表面等离激元极化激元(SPPs)的耦合。石墨烯的SPPs与LiF的SPhPs耦合，形成了随波矢单调增加的耦合SPhP-SPPs色散分支。这种单调增加的色散关系分支与SiC的SPhPs的色散分支相交，导致真空间隙两侧表面模式的耦合，从而在SiC的SPhP频率处共振地增加了热通量。这种表面声子-等离激元耦合也使NFRHT准单色，这对于近场热光伏和热光子学等应用非常理想。这项研究实验证明，石墨烯是一种非常有前景的材料，可用于调节不同介电介质之间NFRHT的大小和光谱。