Design Of Optical Modulator Based On Phase Change Materials

As a key component of optical fiber communication system,the optical modulator plays an important role in the realization of efficient information transmission.Traditional optical modulators face many bottlenecks,such as large volume,poor compatibility and high cost.By artificially designing simple physical structures,metamaterials can generate sub-wavelength resonance at specific frequencies and amplify weak physical phenomena.It provides a new idea mechanism for the realization of optical modulators with low cost,compact size,simple process and high efficiency.Phase change materials(PCMs)changes significantly in electromagnetic properties under specific conditions.By introducing PCMs into optical modulator designing,the optical response of metadevices can be actively tuned without changing physical size.In this paper,a variety of optical modulator models based on GST and V02 are proposed.The metal-dielectric-hybrid modulator with high environmental sensitivity and the all-dielectric modulator with low ohmic loss are studied respectively.In addition,the past research on metamaterial optical modulators focused on terahertz and near-infrared bands.In this paper,optical modulators based on 1550 nm communication band and microwave band are proposed.Firstly,optical switches working in 1550 nm band are proposed.The incident wave is modulated by using metal-dielectric-hybrid,or all-dielectric structures composed of cylindrical array.The influence of cylindrical size and metal type on the modulation effect of hybrid optical switch is studied;the resonant mechanism of three kinds of all-dielectric structures is simulated and analyzed,and the performances of three models based on GST and V02 are compared.A hybrid optical switch with a modulation depth(MD)of 20.18%and a figure of merit(FOM)of 0.899 and an all-dielectric optical switch with a MD of 32.6%and a FOM of 2.692 are achieved.Then,a tunable absorber based on cylinder arrays working at 1550 nm band is proposed.The absorption of structure is affected by the phase transition,so that the absorption effect can be actively tuned.The influence of cylinder size and dielectric film on the modulation is researched,and the polarization response of the ab sorb er is clarified.A metal-dielectric-hybrid absorber with absorption ranging from 96.5%to 15.8%and an all-dielectric absorber with absorption ranging from 96.3%to 52.2%are achieved.Finally,two typical microwave optical modulators are proposed,which are composed of copper split-ring resonators(SRRs)with GST film filled in the gap of SRRs.The resonant response of SRR is tuned by the phase transition of GST.The effects of thickness and composition of GST are also simulated.An active microwave metasurface with MD of 81.09%and a tunable absorber with absorption of 99.89%is obtained.The absorber switches between perfect absorption and total reflection when phase changing.