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|Title:||Optoelectronic Device Modeling Using Field Simulation Techniques|
|Advisor:||Conn, D. R.|
|Department:||Electrical and Computer Engineering|
|Keywords:||Electrical and Computer Engineering;Electrical and Computer Engineering|
|Abstract:||<p>Optoelectronic devices are important devices in optical fiber communications, optical signal processing, and optoelectronic equipment. This thesis develops new models for optoelectronic devices using electromagnetic field simulation techniques. To demonstrate this new technique, two kinds of optoelectronic devices are investigated in this thesis. Vertical cavity surface emitting laseer (VCSEL) is taken as the first research example due to the promising features in the application of fiber communications. A LiTaO₃ electro-optic (E-O) high-speed probe for external electro-optic sampling measurement is the second research example in terms of the need to develop a three-port electrical and optical model for the probe with the coplanar waveguide (CPW) test structure. A new microcavity model for VCSEL is developed in this thesis. The model is based on optical wave equations and implemented with state-space techniques to predict the characteristics of the microcavities. The model can be used to analyze microcavities in both frequency domains in terms of the material parameters and physical parameters of lasers and provides a simple and fast way to optimize cavity length, reflective mirror and material parameters. A three-dimensional discrete time-domain electromagnetic modeling method for microcavities is developed in this thesis. Finite-difference transmission like matrix (FD-TLM) method is modified to involve the distributed optical gain region into the full wave simulation. A simplified microcavity model is developed with the effective mirror derived in this thesis to replace the quarter-wave stacks, and can be used in the full wave modeling of optoelectronic integrated systems having complex inhomogeneities. The near-field and far-field distribution of VCSELs is obtained for the design of interconnections in fiber communication systems. A new dynamic equivalent circuit model for VCSEL is developed in this thesis to add to the equivalent circuit model family of lasers. To describe the laser dynamics, the microcavity model is coupled to the rate equations. A nonlinear resistance is used to represent the optical gain in the cavity. A spontaneous emission noise source is added to the equivalent circuit model to stimulate the noise process throughout the laser operation, which is favored in the system modeling. Stimulation results are compared with the direct rate equation solutions and show that the model is accurate and effective for providing the carrier, photon, optical field, output power, and frequency chirping response of the VCSEL in one simulation. The model enables the laser and its electrical driving circuit to be directly connected and analyzed in a unified manner and can be a powerful computer CAD model to be incorporated into nonlinear circuit modeling software. The model is a useful design tool because it is such a close analogue to the laser device which may be easily modified and enhanced. This thesis addresses the FD-TLM modeling of the LiTaO₃ E-O probe with coplanar waveguides (CPW) test structure with various configurations. A new system transfer function for the probe is defined to sample the signal directly on the sampling point. The full wave modeling of the probe with CPW test structure lays the foundation of the three-port electrical and optical model of LiTaO₃ probe with CPW test structure. To diagnose integrated circuits, it is desirable to measure signal waveforms on internal circuits. LiTaO₃ probe is widely used in E-O sampling due to its high sensitivity and transverse sampling configuration matched to the CPW test structure. Three-port electrical and optical model of the LiTaO₃ probe with CPW test structure is extremely important to the calibration of E-O measurement. With neural network techniques, the field based three-port model is constructed to provide necessary data for the optimum E-O measurement. The three-port has the same accuracy as the full wave modeling, but its characteristics are directly obtained from the neural network weighting parameters rather than the complicated full wave simulation. With this model, it is possible to de-embed both invasiveness and wave-form distortion in the external E-O sampling by giving the sampling configurations, which moves E-O sampling further towards the quantitative measurement.</p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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