Nonreciprocal Properties Of Magneto-optical SOI Waveguides

With the development of modern on-chip integrated optics,nonreciprocal optical waveguides,which are indispensable in integrated optical systems,have quickly become a research hotspot,and are developing in the direction of more miniaturization,integration and intelligence.In this paper,starting from the physical nature of magneto optical effects and magneto optical materials that produce nonreciprocity,the following researches are carried out in the theoretical derivation,numerical calculation and simulation design of nonreciprocal optical waveguides.This paper derives the asymmetric second-order matrix representation of the permeability and permittivity of the two types of magneto-optical materials,gyromagnetic and gyroelectric,under a bias magnetic field.Using these two types of materials,a nonreciprocal surface magneto plasmons(SMPs)that propagates at the interface of silicon and magneto optical materials is studied.It is found that in a certain frequency range,both the fundamental mode and the higher-order mode SMPs can achieve one way propagation.The one way propagation means that one direction of the waveguide can pass light electromagnetic wave,and the electromagnetic wave is cut off in the other direction,the function of optical isolation can be realized.Through numerically calculates the dispersion relation of the waveguide and the band gap of the magneto optical material,it is found that two types of magneto optical materials have similar characteristics in the same silver-silicon magneto optical material planar waveguide structure.By increasing the thickness of silicon layer,the higher order mode appear at the more lower frequency region than before,cause compressing the one way propagation bandwidth.The increase of the external magnetic field can increase the frequency of one way propagation,but there is also the problem of introducing higher order modes.By optimizing the structural parameters of the waveguide,it is found that the one way propagation frequency band of the gyromagnetic material YIG is in the GHz band,and the maximum isolation bandwidth reaches 2.45 GHz,and the one way propagation frequency band of the gyroelectric In Sb is in the THz band,and the maximum isolation bandwidth reaches 3.9THz.It has broad application prospects to realize the isolation of GHz and THz bands.Since the surface magneto plasmons isolation scheme based on straight waveguides is difficult to further increase the isolation frequency band,this paper also studied a kind of magneto optical microring resonant cavity structure based on the simulation to achieve 1550 nm waveband isolation.The basic theoretical formulas of the non-reciprocal phase shift effect and the magneto-optical microring are deduced,and the size of the cross-section magneto-optical material is optimized so that the non-reciprocal phase shift value reaches 6450deg/cm.By simulating a racetrack-type magneto-optical microring with a radius of 50?m,it is found that applying a 40?m Ce:YIG,the racetrack-type magneto-optic microring can achieve 20.4dB isolation at a wavelength of 1542.53 nm.