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Organic Polymer Electro-optic Modulator

Posted on:2010-09-17Degree:MasterType:Thesis
Country:ChinaCandidate:D WangFull Text:PDF
GTID:2208360275983464Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Electro-optic modulator is one of the most important devices in fiber optical communication system. As an integrated optical device, electro-optic modulator based on Mach-Zehnder waveguide has been widely used. Owing to low dielectric coefficient,high electro-optic(EO) coefficient,advantage of fabrication and vertical integration,the research of polymer waveguide electro-optic modulator has been the hotspot both at home and abroad in recent years. At first, the current main structures of the polymer electro-optic modulator were exhibited and research progresses were introduced. Then the structural optimization and simulation, fabrication techniques and optical waveguide measurement of the M-Z ridge waveguide electro-optic modulator were studied as three aspects systematically.Theoretical analysis and simulation of the M-Z ridge waveguide were studied. Optical field distribution was described by a theory based on the combination of the Effective Index Method (EIM) and the Variational Method (VM), and then the single-mode transmission condition for polymer ridge optical waveguide was obtained. Finite Difference Beam Propagation Method(FD-BPM) and Transparent Boundary Condition (TBC) were used to optimize the structure of M-Z ridge waveguide and the best angle of Y-junction was determined as well, and then the optical waveguide structure was simulated by the BeamProp.The principle of Electro-Optic Effect and the principium of M-Z interferometer electro-optic modulator were introduced, and the parameters of the electro-optic modulator were given. The fabrication techniques of the polymer electro-optic modulator were studied in detail. The fabrication steps included substrate cleaning, electrode fabrication, spin-coating of the under-cladding, photolithography, reactive ion etching (RIE), polymer purification, spin-coating of the core and upper-cladding, polarization, and then the structure of traveling-wave electrode was studied.The measurements of effective refractive index and propagation loss of optical waveguide were achieved. A system based on the Prism Coupling Principle and m-line method was designed to measure the effective refractive index of ion-exchange glass waveguide and polymer waveguide. Propagation loss measurement system was designed based on the Liquid Coupling Method. This method chose the liquid instead of the prism to couple the light out the waveguide. The liquid has a higher refractive index than the thin film of the waveguide. Adopting two optical paths the measurement system eliminated the error caused by the non-stability of optical intensity. Analog signal representing light intensity changes which caused by propagation loss was collected by the photo-detector. The two-channel analog signal was converted to digital signal by A/D chip TLC2543, and then transmitted to the computer through RS-232 serial port. Serial communication on PC and MCU was accomplished based on Matlab, and the propagation loss curve was portrayed smoothly through real-time measuring by designed program. The measurement system was nondestructive, precise and real-time,and was useful in waveguides with losses below 0.1dB/cm especially.
Keywords/Search Tags:electro-optic modulator, polymer optical waveguide, waveguide fabrication technique, propagation loss
PDF Full Text Request
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