Principle Of Double Metal Cladding Waveguide And Its Applications

Based on basic optical waveguide theory, this thesis dealt with the ordinary dielectricplanar waveguide and mainly focused on the characteristic of the novel symmetric metalcladding waveguide (SMCW) structure. The SMCW structure is composed of three layers,where a guiding layer is sandwiched between two metal films, which are usually made ofprecious metals, such as gold or silver. Compared with the imaginary part of the complexpermittivity of the precious metals, the real part is usually a large negative quantity in thevisible and near infrared region. As a result, the effective index of the SMCW can exist in theregion of0<N<∞. Besides, owing to the millimeter scale guiding layer of the SMCWstructure, ultrahigh order modes with effective index ranged in the region0<N<1can beeffectively excited. Such ultrahigh order modes exhibit special features, such as significantenhanced sensitivity to incident wavelength and the refractive index of the guiding layer,insensitive to the polarization of the incident laser.One application of the SMCW structure is designing a high sensitivity hollow-coremetal-cladding waveguide sensor. Since the effective index of the ultrahigh order modes canapproach zero, which is no longer limited by the conventional limitation that the effectiveindex of the guiding layer must exceed that of the cladding layer. This advantage is extremelyuseful when we research the sample under aqueous environment and natural bio samples. It isneed to mention here the detected samples are placed in the guiding layer where oscillatingelectromagnetic field propagates, so the proposed sensor is also known as the oscillating wavesensor. In the third paragraph, the sensitivity of the hollow-core metal-cladding waveguidesensor and the traditional SPR sensor, long range SPR sensor, leak waveguide sensors andanti-symmetric waveguide are deduced and analyzed theoretically, and we obtained ananalytical expression for the sensitivity with clear physical insight. Numerical comparison with those evanescent field sensors, the sensitivity of the new biosensor is increased by atleast two orders of magnitude. Meanwhile, we presents the detailed production process of thehollow-core metal-cladding waveguide sensor, and analysis the impact of the structureparameter on the ATR spectrum via self made software. Furthermore, the growth of E. ColiO157:H7under different temperature and concentration of diluted glucose solution are alsodetected to demonstrate the sensitivity and response time of the sensor experimentally.Experimental results show that new biosensor is capable of directly detecting concentration ofglucose as low as1ppm, and real-time monition of growth of E. Coli O157:H7under thelaboratory conditions. The new biosensor has a good application potential owing to itsadvantages such as good stability, high reliability and low cost.The other application of the SMCW structure in this thesis is a new scheme to measurethe electro-optical (EO) and converse-piezoelectric (CPE) coefficients of the PMN-PTceramics simultaneously. Despite its extensive application in optical switch, opticalattenuation, electro-optic modulators and other optoelectronic devices, the values of EO andCPE coefficients of PMN-PT have not been completely known and usually depend on anumber of simulation software. If only consider the EO coefficients, they can be determinedby one-beam-ellipsometric technique for measuring the induced phase retardation betweentwo orthogonal plane-polarized lights and by two-beam-interferometric arrangements, such asMach-Zehnder and Michelson interferometers, for measuring the interference between twoparallel plane-polarized lights. On the other hand, the CPE coefficients are always determinedfrom the resonance frequencies by the IEEE standard technique. Diverse as measurementtechniques are, they can be characterized by one common shortage, namely involving onlyone effect. There is no effective way to analyze the EO and CPE coefficients simultaneously,while the variation of the detected quantity should be the results of both the variation inrefractive index due to EO effect and the change in sample thickness resulting from the CPEeffect, when an electric field is applied to PMN-PT ceramics. Therefore, it is highly expectedthat a simple and effective method to measure the EO and CPE coefficients of PMN-PTceramics simultaneously. This is what we studied in the fourth paragraph of the thesis.