張碩,李宇博,付淑芳
黑磷-硫化鋅異質(zhì)結(jié)表面古斯-漢欣位移的可調(diào)性
張碩,李宇博,付淑芳
(哈爾濱師范大學(xué) 物理與電子工程學(xué)院,黑龍江 哈爾濱 150025)
基于傳輸矩陣和表面聲子極化子理論,設(shè)計(jì)了黑磷-硫化鋅異質(zhì)結(jié)來(lái)實(shí)現(xiàn)對(duì)遠(yuǎn)紅外區(qū)間反射光束古斯-漢欣(GH)位移的調(diào)控.理論計(jì)算結(jié)果表明,通過(guò)控制黑磷的電荷摻雜密度及各項(xiàng)異性軸方向等因素,GH位移可被調(diào)控且其最大值甚至可達(dá)到真空波長(zhǎng)的68倍左右.這些研究結(jié)果對(duì)于新型納米光學(xué)器件的研究具有重要意義.
黑磷;古斯?漢欣位移;雙曲材料
眾所周知,當(dāng)近軸光束入射到介質(zhì)界面時(shí),實(shí)際反射光束相對(duì)于幾何光學(xué)預(yù)測(cè),光束具有輕微橫向偏差.這一現(xiàn)象被稱為古斯-漢欣位移(Goos-H?nchen,GH),并由Artmann在20世紀(jì)40年代末進(jìn)行了理論證實(shí)[1].考慮到光與物質(zhì)相互作用的特性,相關(guān)的研究已經(jīng)從最原始的界面結(jié)構(gòu)擴(kuò)展到各種界面系統(tǒng),如自由空間與極性晶體[2]、光子晶體[3]、金屬[4]、超材料[5]或天然雙曲晶體[6]組成的界面系統(tǒng).在通常情況下,GH位移的大小與普通電介質(zhì)的真空波長(zhǎng)相當(dāng),這使得GH位移難以被測(cè)量和應(yīng)用.量子弱測(cè)量技術(shù)的建立使得精確測(cè)量GH微小位移成為一種可能[7-8].另一方面,實(shí)現(xiàn)GH位移的直接測(cè)量是拓寬其應(yīng)用領(lǐng)域的一個(gè)重要途徑.為此,研究者們提出了各種強(qiáng)位移高反射的結(jié)構(gòu),如左手超材料[9]、超表面[10]、各向異性超材料[11]和石墨烯包覆的光子晶體[12]等.此外,在某些特定情況下,如布魯斯特角和臨界角附近,GH位移可以增大很多且可以是正位移或負(fù)位移[13].Ziauddin[10]等報(bào)道了在固定配置或設(shè)備中,通過(guò)超光速和亞光速波傳播對(duì)GH位移的相干控制.
近年來(lái),黑磷由于其優(yōu)越的光電特性而受到越來(lái)越多科研人員的關(guān)注.這是因?yàn)橐环矫婧诹自谥羞h(yuǎn)紅外的頻率范圍內(nèi)介電表現(xiàn)出二維雙曲特性;另一方面黑磷作為半導(dǎo)體,具有0.3~2 eV的直接帶隙[14-15],這些特性使得黑磷作為高遷移率的二維半導(dǎo)體材料而被廣泛應(yīng)用于電子輸運(yùn)等領(lǐng)域.最新研究發(fā)現(xiàn),在黑磷光軸的方向、摻雜濃度和帶間躍遷都會(huì)對(duì)表面的自旋霍爾效應(yīng)產(chǎn)生巨大的影響[16].這些優(yōu)異的結(jié)構(gòu)特性都使黑磷成為一種理想的光學(xué)位移調(diào)控材料.此外,以硫化鋅或納米碳化硅為代表的離子晶體,具有非常低的光損耗,而且在紅外范圍內(nèi)激發(fā)的表面聲子極化子(SPhPs)比金屬表面激發(fā)的表面等離子極化子(SPPs)傳播的距離更長(zhǎng)[17-18].這些特性都使得離子晶體成為了光學(xué)領(lǐng)域內(nèi)研究的熱門材料.
本文提出了一種在硫化鋅表面覆蓋多層黑磷的異質(zhì)結(jié)結(jié)構(gòu).與基于金屬的超材料不同,黑磷-硫化鋅異質(zhì)結(jié)的耗散損耗要低得多,且通過(guò)調(diào)控黑磷的化學(xué)勢(shì)、各向異性軸方向、厚度以及入射角可達(dá)到調(diào)控GH位移的目的.結(jié)果表明,黑磷-硫化鋅異質(zhì)結(jié)結(jié)構(gòu)對(duì)調(diào)控GH位移提供了一種可能的途徑.
圖1 黑磷-硫化鋅結(jié)構(gòu)及黑磷示意圖
由方程(3)可求得黑磷中的波矢為
可得到GH位移的解析表達(dá)式為
圖2 黑磷和硫化鋅介電函數(shù)隨頻率變化的曲線
圖3 不同摻雜濃度條件下GH位移隨頻率變化的曲線
圖4 不同入射角條件下GH位移隨頻率變化的曲線
圖5 GH位移隨著黑磷偏轉(zhuǎn)角和層數(shù)變化圖像
[1] Goos F,H?nchen H.Ein neuer und fundamentaler Versuch zur Totalreflexion[J].Ann Phys,1947,436(7-8):333-346.
[2] Shaltout A,LiuJJ,KildishevA,et al.Photonic spin Hall effect in gap-plasmon metasurfaces for on-chip chiroptical spectroscopy[J].Optica,2015,2(10):860-863.
[3] Wang L G,Zhu S Y.The reversibility of the Goos-H?nchen shift near the band-crossing structure of one dimemsional photonic crystals containing left-handed metamaterials[J].Appl Phys B,2010,98:459-463.
[4] HermosaN,NugrowatiAM,AielloA,et al.Spin Hall effect of light in metallic reflection[J].OptLett,2011,36(16): 3200-3202.
[5] Kong Q,Shi H,Shi J,et al.Goos-H?nchen and Imbert-Fedorov shifts at gradient metasurfaces[J].Opt Express,2019,27(9):11902-11913.
[6] GuddalaS,KhatoniarM,YamaN,et al.Optical valley Hall effect of 2D excitons in hyperbolic metamaterial[J].Optica,2021,8(1):50-55.
[7] Hosten O,Kwiat P.Observation of the spin hall effect of light via weak measurements[J].Science,2008,319:787-790.
[8] GoswamiS,DharaS,PalM,et al.Optimized weak measurements of Goos-H?nchen and Imbert-Fedorov shifts in partial reflection[J].Optics Express,2016,24(6):6041-6051.
[9] WangLG,Zhu SY.Large positive and negative Goos-H?nchen shifts from a weakly absorbing left-handed slab[J].Journal of Applied Physics,2005,98(4):043552.
[10] Ziauddin,Chuang You-Lin,Qamar S,et al.Goos-H?nchen shift of partially coherent light fields in epsilon-near-zero metamaterials[J].SCIENTIFIC REPORTS,2016,6:26504.
[11] Cai L,Zhang S,Zhu W,et al.Photonic spin Hall effect by anisotropy induced polarization gradient in momentum space[J].Opt Lett,2020,45:6740.
[12] Wu Shu-qi,Song Hao-yuan,Li Yu-bo,et al.Tunable spin Hall effect via hybrid polaritons around epsilon-near-zero on graphene-hBN heterostructures[J].RESULTS IN PHYSICS,2022,35:105383.
[13] Wang X G, Zhang Y Q, Zhou S,et al.Goos-H?nchen and Imbert-Fedorov shifts on hyperbolic crystals[J].Opt Express,2020,28(17):25048.
[14] Lu J,Wu J,Carvalho A,et al.Bandgap engineering of phosphorene by laser oxidation toward functional 2D materials[J].ACS
Nano,2015,9(10):10411-10421.
[15] Li D,Xu J R,Ba K,et al.Tunable bandgap in few-layer black phosphorus by electrical field[J].2D Mater,2017,4(3):031009.
[16] Zhang W S,Wu W J,Chen S Z,et al.Photonic spin Hall effect on the surface of anisotropic two-dimensional atomic crystals[J].Photon Res,2018,6(6):511-516.
[17] Fu S F,Zhou S,Zhang Q,et al.Complete confinement and extraordinary propagation of Dyakonov-like polaritons in hBN[J].Optics and Laser and Technology,2020,125:106012.
[18] Zhou S,Abdullah K,F(xiàn)u S F,et al.Extraordinary reflection and refraction from natural hyperbolic Materials[J].Opt Exp,2019,11(27):15222.
Tunability of the Goos-H?nchen shift on the surface of black phosphorus-ZnS heterostructure
ZHANG Shuo,LI Yubo,F(xiàn)U Shufang
(School of Physics and Electronic Engineering,Harbin Normal University,Harbin 150025,China)
Based on the transmission matrix and surface phonon polaritons,a black phosphorus(BP)-ZnS heterostructure is designed to regulate the Goos-H?nchen(GH)shift of reflected beams in the far infrared region.Theoretical calculation results show that the GH shift can be tuned by controlling the charge doping density and anisotropic axis-orientation of BP,and the maximum value of GH shift can even reach 68 times vacuum wavelength.These results are of great significance for the research of new nano-optical devices.
black phosphorus;Goos-H?nchen shift;hyperbolic material
1007-9831(2022)08-0045-07
O431.1
A
10.3969/j.issn.1007-9831.2022.08.010
2022-04-06
張碩(1998-),女,黑龍江齊齊哈爾人,在讀碩士研究生,從事雙曲材料表面光學(xué)性質(zhì)研究.E-mail:3479277601@qq.com
付淑芳(1975-),女,黑龍江雙鴨山人,教授,博士生導(dǎo)師,從事雙曲材料表面光學(xué)性質(zhì)研究.E-mail:shufangfu75@126.com