Design Of A Tunable Optical F-P Filter Based On Electrostatic Driving

Tunable optical filter is a frequency selective device; you can also say that it is a wavelength selection device. Its main purpose is to extract specific frequencies or wavelengths of light from the mixed signals, which includes many different frequencies of light waves. A good performance tunable optical filter should have a narrow bandwidth to allow the channel spacing is small, wide FSR and narrow half-height to accommodate more channels, fast wavelength switching speed, wide wavelength stability and high precision etc.The main work of this thesis includes design of the tunable optical F-P filter based on electrostatic driving, the calculation of static drive and ANSYS simulation. First, design the main part of the tunable filter for optical structure, filter structure includes the input and output light waveguides, two symmetric DBR, silicon waveguide F-P resonator, MEMS electrostatic comb electrodes etc. I expound the design of the F-P cavity and the DBR mirror structure and SOI ridge waveguide structure. Based on these optical structural parameters, simulate the performance of the filter and gives the frequency shift tuning characteristics. Second, the silicon platform of F-P cavity make up of the optical waveguide and two DBR mirrors, the platform is connected by elastic beam and the electrode. Starting from the filter performance to determine the F-P cavity and DBR mirror, calculate the middle of silicon platforms change, which affects the refractive index, by the wavelength tuning range and then calculated the size of electrode size and the need for power. Based on the above work, using the electromagnetic, structural dynamics, finite element method theory to design the comb electrode, analyze that the voltage, which loads to the MEMS electrostatic comb electrode, generate the, and the electrostatic force moves electrode DBR. I calculated the natural frequency, sensitivity and vibration electrode with no damping and damping conditions. Again, for two or more works by the interaction between the formations of physical coupling field calculation alone is not enough. We used ANSYS finite element analysis software to simulate the coupling field, modeled the overall movable electrode, and simulation. Static analyzed and calculated the response of structures with the fixed load, the simulation results agreed with the theoretical design. Finally, analyze the dynamic model, including modal analysis and transient dynamic analysis, analyze the natural frequency and vibration mode, and understand the vibration characteristics of the model.The innovation of this design is the use of SOI waveguide, F-P cavity, electrostatic comb-shaped electrode integrated structure, compact novel, and is easy to integrate other optical components. This integration of photonic-based optical waveguide on silicon wafer polishing filter is a basic component interconnection unit, which is a key function in photonic integrated devices. In addition, the use of electrostatic comb electrode structure, two symmetric DBR while moving, by adjusting the cavity length of F-P cavity to achieve the equivalent function of the tunable filter has the characteristics of wide tuning range.Significance of this research is to study the design of ridge waveguide based on SOI, MEMS electrostatic drive, F-P cavity integrated in one tunable optical filter. When the comb-shaped electrode voltage is applied, with the effect of static electricity, movable electrode drive movable DBR, causing the F-P equivalent cavity length change, in order to achieve tunable filter function. In addition, re-discuses the static electricity application in the MEMS system. Although some of the static electricity in the micro-mechanical systems have been widely used and have been commercialized, its design concept and design tools have not been able to achieve the intended purpose. Combined with a variety of disciplines, intensive development of cutting-edge science of today's results will make MEMS gradually from the laboratory to practical use.ANSYS as a major software design of this device is a widely used commercial package of engineering analysis software. Is the so-called "bricks without straw his tools." ANSYS is currently the most widely used, and also is the most powerful finite element software. We apply this software tunable optical filter to simulate the driving part, combined with today's advanced algorithms and analysis of concepts, simulate electrode work situation. Therefore, using the software to analyze the MEMS system can find a good meeting point.Prospects for future work, considering the author's level that can carry out specific research in the following: Sensitivity calculation extended to the filter part; Reduce the damping effect impacting on the system; Analysis of coupled field; Design drive circuit.