Study Of Micro Nano Photonic Devices Based On Optical Tamm States

Optical Tamm States（OTS）are derived from the analogy of Tamm states in solid state physics and widely exist in one-dimensional photonic crystal heterojunctions and metal-photonic crystal structures.OTS excitation can also be realized by introducing metal-photonic crystal and metal-Bragg grating structure into metal-dielectric-metal（MDM）waveguide.Based on OTS in MDM,the design and research of micro-nano photonic devices are completed as follows:An all-optical switch based on OTS is designed.The optical switch is composed of an MDM waveguide,a metal baffle in the waveguide core,and a photonic crystal on the upper side of the MDM waveguide.The photonic crystal unit structure is composed of Al₂O₃and nonlinear material Ga As.The signal light is transmitted along the MDM waveguide,and the transmission spectrum is asymmetrically distributed in the Fano resonance line shape.The wavelength of the signal light is the resonance wavelength,and the all-optical switch is in the state of"on".When the pump light is incident from the upper side,due to the nonlinear effect,the refractive index of Ga As material changes and the Fano resonance wavelength shifts.At this time,the all-optical switch changes from"on"to"off".The extinction ratio is 23.82d B and the insertion loss is 4.42d B when the signal wavelength is 1550nm.A tunable,two-band narrow-band absorber based on optical-like Tamm state is designed.By introducing metal film-Bragg gratingⅠ-Bragg gratingⅡ-metal film structure into MDM waveguide,when the wave-vector matching condition is satisfied,the optical Tamm-like state can be excited at the metal film-Bragg grating interface,and the incident light is localized at the metal film-Bragg grating interface,so as to achieve narrow band absorption.Meanwhile,tunable absorption is realized by changing the refractive index of the medium in the Bragg grating and changing the excitation wavelength of optical-like Tamm state.By optimizing the parameters,narrow band absorption of 1100nm-1800nm and 1400nm-2200nm with absorption rate greater than99%was obtained.A novel mechanism of Fano resonance using optical Tamm state as discrete state is proposed.Based on this,a high quality factor refractive index sensor is designed.The sensor consists of an MDM waveguide,a metal film in the waveguide and a Bragg grating structure on one side of the waveguide.When the optical signal is transmitted to the metal film along the MDM waveguide,a small part of it can penetrate through the metal film,and the transmission spectrum is continuous state.At the same time,when the wave-vector matching condition is satisfied,the tamm-like state on the Bragg grating and the metal interface can be excited.The mode is discrete state,and the coherent superposition of the two can generate Fano resonance.When the refractive index of the medium in the Bragg grating changes,the Fano resonance wavelength shifts,so as to realize the refractive index sensor.Through parameter optimization,the FOM value of the refractive index sensor can reach 3.2×10⁵,and the sensitivity is 1500nm/RIU.