Design Of Narrowband Optical Resonant Structures And Their Thermal Response Analysis

The narrowband optical resonant structure represented by optical microcavity,Tamm plasmon polariton,guided mode resonance,BIC et al,has high quality factor and strong field local characteristics,which can enhance the interaction between light and matter,and is widely used in laser,detection,and sensing fields.With the goal of reducing the spectral bandwidth of narrowband optical resonant structures,this dissertation carries out a series of theoretical explorations to obtain ultra-narrowband optical resonant structures through simulation design and structural optimization,and discusses the application of narrowband optical resonant structures in thermal sensing.Aiming at the problem of low absorption rate of narrowband optical resonant structures in the infrared spectrum,this dissertation further carries out the simulation design and structural optimization of infrared absorption enhancement.The specific research content includes the following parts:1.The photonic crystal defect state structure and the photonic crystal optical Tamm state structure were designed based on one-dimensional photonic crystals.Focusing on the optical mode characteristics,quality factors,process errors and thermal sensing sensitivity,the two structures are analyzed theoretically.A thermal sensing structure based on the one-dimensional photonic crystals defect state was designed and prepared,and temperature response test experiments were carried out,through which the feasibility of utilizing narrowband optical resonant structure to achieve thermal sensing was verified.A differential intensity detection technique under dual resonance wavelength operation is proposed to improve the sensitivity of light intensity detection.Based on mode coupling method,the mode hybrid structures with dual-resonance wavelengths were constructed.The spectral characteristics and the refractive index sensing performance of the mode hybrid structures were studied.The results show that,the mode coupling method can flexibly construct an optical system with dual-resonance wavelength on the one hand,and effectively suppress the loss in the system and improve the quality factor of the optical resonant system on the other hand.2.Based on the high-quality factor optical properties of guide mode resonance,the planar waveguide guide mode resonance and grating waveguide guide mode resonance structures were designed.The effects of structural parameters on spectral characteristics of guide mode resonance structure under different polarizations were studied,and the thermal response of the structures was analyzed.The results demonstrate that the grating waveguide GMR structure can obtain a Q value of up to 5724 and a FOM value of up to0.343 K^-1 under TE polarization.A method of introducing a metal layer on the guide mode resonance structure is proposed,with the aim of improving the thermal sensing sensitivity of the structure by enhancing the localization of the electric field in the waveguide layer,among which the planar waveguide GMR/metal composite structure can obtain a thermal sensing sensitivity of 0.071 nm/K,which is close to the theoretical calculation limit value.3.Based on the high-quality factor optical properties of BIC,a two-dimensional BIC structure and a three-dimensional BIC structure were designed.The formation mechanism of the high-quality factor resonant peaks of the two BIC structures,the influence of structural parameters on the spectra,and the corresponding thermal sensing sensitivity were studied.The simulation results show that the three-dimensional BIC structure can obtain a thermal sensing sensitivity of up to 0.071 nm/K,but the introduction of substrate will lead to a significant decrease in sensitivity.Aiming at the problem of substrate influence,a two-dimensional BIC structure is proposed,and the results show that,under TE polarization,the introduction of substrate will lead to the emergence of a new quasi-BIC mode,the Q value of this mode reaches 6284,the thermal sensing sensitivity reaches0.07 nm/K,and a FOM value of up to 0.5 K^-1 can be obtained.4.The narrowband optical resonant structure is applied to the optical readout infrared thermal sensing system,and an optical readout infrared thermal sensing system with temperature compensation function is proposed.Aiming at the problem of low infrared absorption of narrowband optical resonant structure,an MIM metasurface with single-or double-band infrared absorption characteristics is designed.And the infrared absorption spectrum is broadened by introducing an ultra-thin Epsilon Near Zero（ENZ）layer.Two kinds of structures with ultra-wideband infrared absorption characteristics were designed,which adopt the all-dielectric metasurface design based on Mie resonance and the pyramid-shaped periodic structure design of ENZ/Al multilayer film system based on ENZ mode,respectively.The infrared absorption mechanism of the two structures was analyzed,and the effects of process error,polarization state and incident angle on the absorption were studied.The results show that the average absorptivity of 52%and 92%in the long wave infrared（LWIR）spectrum can be achieved within the incidence angles of 60°and 40°,respectively.One-dimensional grating structural and grid array structural design of SiO₂/Al bilayer system was prepared.The spectral test results show that the periodic structural design of SiO₂/Al bilayer system can effectively stimulate the ENZ mode of SiO₂ layer and realize the absorption enhancement at ENZ wavelength.