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Studies Of MZI Sensing Chips Based On Integrated Polymer Waveguides

Posted on:2005-02-07Degree:DoctorType:Dissertation
Country:ChinaCandidate:J XuFull Text:PDF
GTID:1118360122987910Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
The application of polymers (as passive waveguide materials) to intergrated optical sensing (evanecent wave sensing) is a new try as compared with that in thermal sensing [using thermo-optic (TO) modulators] or voltage sensing [using electro-optic (EO) modulators]. Compared with other materials, polymers have many advantages such as low cost, easy fabrication, better fixation to the sensing polymer film, and the potential for integrating with a TO or EO modulator for a fine tuning of phase. Reducing the cost is currently of great need to accelerate the development of integrated chemical senors, and the study in the present thesis is partially for this purpose.In view of the potential of MZI( Mach-Zehnder Interferometer) sensing structures, useful features of ARROW (Antiresonant Reflecting Optical Waveguide) and promising future applications of refractometers, MZI refractometers based on polymeric ARROW structure are studied in this thesis.The phase difference in the two arms of a MZI is vital for a MZI-based sensor, and the phase (of each lightpath) should be determined with an accurate modal analysis. In the present thesis, the methods of leaky mode analysis are sumarized and a comparison is given with some examples. The Kumar's method and the finite difference mode solver (with nonuniform grid and PML boundary treatment) are extended to calculate the leaky loss. A rib ARROW structure based on a polymeric material is analyzed, and its characteristics such as the leaky loss, the sensitivity, the coupling loss to an optical fiber, the decoupling distance and the minimal bending radius are discussed in detail, and the optimized results are obtained. To solve the intrinsic problem of trade-off between the sensitivity and the sensing range in a sensor based on a single MZI, a double-MZI structure is applied to realize a double-precision measurement. According to the requirements for the sensing range and the operating point, an appropriate thickness of the overlayer and the reference refractive index are chosen. The fluorinated polyamic acid solution and film material are then produced, and many surface quality problems such as air bubbles, cracks and surface roughness are solved. Polymer films with uniform thickness and uniform refractive index are obtained. Finally, a MZI refractometer is fabricated and many experimental conclusions about polyimide process techniques (such as metal mask fabrication with lift-off method, ICP etching and surface adhesion enhancing with silicon wafer) are given.
Keywords/Search Tags:sensor, fluorinated polyimide, leaky mode analysis, ARROW, MZI
PDF Full Text Request
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