Microwave Magneto-optical Properties Of Metal Cladding Waveguide Structure

Magnetostatic waves (MSWs) are a kind of low dispersion waves. A zero or linear dispersion delay for MSWs can be obtained in a metal clad waveguide, multilayered waveguide or cascaded magnetostatic forward/backward wave-based system. As an ideal dielectric for propagating MSWs and guided optical waves (GOWs), an yttrium-iron-garnet (YIG) film is often used to investigate their interaction. In comparison with acousto-optic Bragg devices, the MSW-based magnetooptic (MO) cells are capable of providing faster modulation speeds, broader bandwidths and simple microstrip designs with potential applications to optical communication, signal processing and laser radar.To make researches on MO Bragg cell-based optical signal processing and obtain high performances of MO Bragg devices, the excitation and propagation of MSWs are discussed in the obliquely magnetized waveguide coated with perfect metal layers and MO interactions between three types of MSWs and GOWs are also investigated. The main contents and innovations are as follows:1. The MSW propagation equation and dynamic magnetization are obtained in the obliquely magnetized metal/ dielectric/ YIG/ gadolinium-gallium-garnet (GGG)/ metal structure. It is pointed out that the distribution of RF potential field can be used to distinguish all three types of MSWs.2. In the obliquely magnetized waveguide coated with metal layers, the dispersion relation of magnetostatic surface waves (MSSWs) is given, and the dispersive branch and the bandwidth corresponding to the MSSW envelop solitons are also determined.3. A tunable magnetostatic forward volume wave (MSFVW)-magnetostatic backward volume wave (MSBVW) cascaded delay line is designed in the metal clad waveguide, which has a 500MHz non-dispersive bandwidth and a 30ns/cm differential time delay.4. By considering phase-mismatching conditions, a simplified MO coupled-mode equation for the interaction between MSWs and GOWs in the metal clad waveguide is obtained. Calculation shows that, the diffraction effect of GOWs induced by MSSW or MSFVW can be enhanced by metal effects, which is also explained qualitatively through the wave number deviation, and the 8.7dB DE improvement comparing with the case of the sandwich waveguide is achieved in the dispersion branch where MSSW envelop solitons can be generated.5. The concept of"magnetization grating"is proposed for the first time and the kind of grating can provide a potential application to the BPSK communication, grating sensor and optical switching.