Research On The Tunability Of Magneto-optical Resonantor Loops With Its Applications

With the development of optical fiber technology,optoelectronic integration and optical communication in recent years,optical communication equipment has continued to develop in the direction of functionalization,integration and miniaturization.On the other hand,mode division multiplexing technology has attracted more attention to satisfy the increasing demand for bandwidth.This paper combines the magneto-optical effect with device integration and mode multiplexing to study the mode characteristics of two magneto-optical resonant ring structures,those of magneto-optical planar waveguide and magneto-optical fiber.According the magnetic tunability of the resonant ring structures,the microstrip-controlled magnetic fluid micro-ring optical switch and fiber LP-mode detection scheme are put forward.The main contents and innovations of this article are as follows:1.The mode characteristics of two kinds of magneto-optic waveguides are analyzed by the COMSOL simulation software.One is a silicon-based planar waveguide with a magnetic fluid cladding.The dependence of the number of supported modes on the applied magnetic field and waveguide size are simulated.In order to achieve the single-mode operating condition for the silicon-based waveguide device,the cross-section of the silicon-based waveguide are 0.6 ?m × 0.25 ?m by optimization,and then the fundamental mode propagation constant dependent on the applied magnetic field is simulated.The other is a magneto-optical fiber,whose mode characteristics are focused on by comparison with those of the few-mode fibers available in communication.Combining the spatial mode in the magneto-optical fiber with the leftand right-handed circular polarization states,we give the nomenclature of the vector modes in the magneto-optical fibers.The mode field dependency of the magneto-optical coupling coefficients is theoretically analyzed and the obtained results are consistent with the simulated ones.2.A micro-ring optical switch chip with the magnetic fluid cladding controlled by the microstrip line is proposed,in which the drive currents in the two ring metal microstrip lines integrated on the inner and outside of micro-ring waveguide are applied in the opposite direction.The optical switch function can be achieved by changing the currents input to the metal microstrip line.Taking a single micro-ring resonator as an example,we describe the optimization design process of the ferrofluidic switch chip,including the determination of the perimeter of the micro-ring resonator,the coupling ratio between the input-output silicon wire waveguide and the silicon-based microring and applied magnetic field.Simulation results show that,a small switching magnetic field of 150 Oe(the corresponding microstrip line current is about 447mA)can be used to the microring optical switch chip at the working wavelength of 1550 nm,with the extinction ratio of 10 dB.3.A method of detecting the linear polarization mode in fibers based on a multi-mode magneto-optical fiber ring is proposed.The dependency of the magneto-optical coupling coefficients on the mode field and applied magnetic field is first used to calibrate the transmittance of each intrinsic mode of the magneto-optical fiber ring under different bias magnetic fields.Then,the beam under test containing multiple fiber modes is injected into the magneto-optical fiber ring,and then the insertion loss under different magnetic fields is measured.The linear polarization mode is regarded as the superposition of left-handed and right-handed circularly polarized light.Finally,the proportion of each linearly polarized modes can be calculated from the data given by the previous steps.The feasibility of this method is verified by COMSOL simulation,in which the few-mode magneto-optical fiber with a core diameter of 9?m is used for detecting the input beam composed of three linear polarization modes as an example.