Research On The Optical Properties Of Embedded Chalcogenide Two-dimensional Materials In Optical Microcavities

Two-dimensional nanosheets of layered transition metal dichalcogenides?TMDs?lies in the visible and near infrared range,which has many novel properties.It has become an attractive material in the field of photoelectric devices,such as photoelectric detection,light capture,photoelectric transistor,led and laser,etc.The coupling of these materials to various optical nano-cavities can enhance the quantum yield of exciton emission to achieve good quantum optics and nano-photon devices.Here,we mainly study the exciton coupling characteristics of single-layer TMDs embedded in one-dimensional photonic crystal microcavities.The optical properties of single-layer two-dimensional WS₂ and MoS₂ were studied,with special attention paid to their photoluminescence,Raman spectrum,etc.A new method to characterize the refractive index of two-dimensional materials was developed by embedding microcavities.Last but not the least,one-dimensional graded optical microcavity devices with good spectral characteristics at 630-670 nm bands were fabricated.The main research results are as following:1.Taking WS₂ and MoS₂ as examples,the single-layer WS₂ and MoS₂ mat erials were embedded into the one-dimensional photonic crystal optical microca vity respectively,and the peak positions of the transmission spectrum of the sa mples with and without embedded WS₂ and MoS₂ were observed to have a re dshift of 6.88 nm and 3.36 nm,respectively.The refractive indexes of the sing le-layer WS₂ and MoS₂ were calculated asn_WS2?28?5.11andn_MoS2?28?3.73.The cal culatedvalue of extinction coefficient of the single-layer WS₂ and MoS₂ respecti vely were _WS and _MoS?.Results show that the method can s olve the difficulties in measuring micron scale 2D material index of refraction and achieve accurate measurement,has the very good universality,is particularl y applicable to the following the ultrathin film refractive index determination,p rovides a small scale,ultra-thin materials refractive index measurement,for the design and application of optical devices,optoelectronic devices and developm ent provides an important technical foundation.2.The coupling of light and exciton in a single WS₂ two-dimensional atom ic crystal is studied.High quality single layer WS₂ was embedded into the medi um microcavity at suitable temperature.Due to the coupling between single laye r WS₂ excitons and cavity photons,Rabi splitting of 34.2meV was observed in angular resolution reflectance spectrum.The anticrossover behavior and the for mation of the lower polariton branch?LPB?and the upper polaritonbranch?UPB?were observed at room temperature.It provides an attractive way to develop pr actical polarization devices.3.By tilting the intermediate cavity layer and the upper and lower half DBR,we discussed three different methods.The one-dimension graded microcavity was prepared by the method of ion source assisted deposition and optical monitoring.we showed that the prepared one-dimensional graded integrated microcavity not only had good spectral characteristics in 630-670 nm,but also had a width of less than 1nm.The method to obtain one-dimensional graded optical microcavity by means of multiple coating combinations can be combined with the embedding work of microcavity in this paper,those are more useful experimental data can be obtained at one time,which provides a new idea and approach for related work.