Design And Simulation Of Magneto-optical Signal Processing Chips

Magneto-optical devices have a wide range of applications in the fields such as optical communication and optical sensing,but most of magneto-optical devices are relatively large in size,which is hard to be integrated in large scale.Silicon-based integrated chips as current research hotspot have become an important evolution direction for miniaturization.Our objective is to combine magneto-optical materials with silicon-based waveguides to develop silicon-based magneto-optical devices and multifunctional integrated chips.According to the principle of magneto-optical non-reciprocal phase shift,two kinds of magneto-optical signal processing chips for magnetic field sensing and magneto-optical switch were designed by analyzing the magnetization dependences of the propagation constant of guided optical waves in the magneto-optical waveguide.The main contents and innovations of this thesis are listed as follows:1.One-dimensional,two-dimensional and three dimensional magnetic field sensing chips using silicon-based magnetic optical waveguides are designed.The one-dimensional magnetic field sensing chip is realized by a Ce:YIG/Si/SiO₂magneto-optical waveguide structure.Further,a new waveguide structure of Ce:YIG/Si-Ce:YIG/SiO₂ with magnetic field sensitivity in the cross-sectional plane is presented and is used to form the micro-ring resonators for two-dimensional and three-dimensional magnetic field sensing.The magnitude and direction of magnetization or magnetic field can be determined by the resonant wavelength shifts for the TE and TM modes.By optimizing the waveguide cross-section,for the magnetic field sensing chips the magnetization sensitivity in the normal and tangential directions at the wavelength of 1550nm can be achieved 0.105pm/[?kA/m??m]and0.080pm/[?kA/m??m],respectively.2.According to the principle of magneto-optical non-reciprocal phase shift,two kinds of magneto-optical switch chips are designed.One is the magneto-optical switch with cascaded double rings,and the 3d B bandwidth and extinction ratio are respectively0.8nm and 15d B by optimizing parameters such as microring radius and coupling coefficient.The other is composed of a magneto-optic micro-ring array and a Sagnac structure.The influence of the micro-ring array structure on the switching magnetic field and the optical switching characteristics are specifically studied.By analyzing the phase shift characteristics of cascaded magneto-optic microrings,the effects of magnetization,waveguide coupling coefficient and waveguide loss on the transmittance and 3d B bandwidth at the central wavelength were simulated and calculated.The magneto-optical Sagnac switch has an insertion loss of less than 1 d B and a bandwidth of 1.6 nm at the center wavelength of 1550 nm,corresponding to the switching magnetization of 57.3 kA/m.3.Taking the Sagnac magneto-optical switch chip as an example,the dynamic characteristics of the magneto-optical device are analyzed from the frequency response of the microstrip line exciting magnetic field and the microwave characteristics of the magneto-optical material itself,and the response time of the optical switch is nanosecond order of magnitude.According to the frequency dependence of the impedance of the microstrip line,the 1dB cut-off frequency of the Sagnac magneto-optical switch is calculated to be 220 GHz,dependent on the microstrip line size and the effective dielectric constant.According to the AC magnetization characteristics of the magnetic susceptibility tensor for the magneto-optical material,the frequency response of the optical switch is analyzed,and the resonant frequency is related to the magnitude of the dc magnetic field.Finally,the Sagnac magneto-optical switch has some advantages in extinction ratio and switching speed by comparison with other optical switches.