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Metal - dielectric micro-nano composite structures and photonic device applications

Author: GuoXin
Tutor: TongLiMin
School: Zhejiang University
Course: Optical Engineering
Keywords: Fiber satisfied Ring resonator Optical Sensing Semiconductor nanowires Metallic nanowires Surface plasmon Beamsplitter Mach-Zehnder interferometer
CLC: TN256
Type: PhD thesis
Year: 2010
Downloads: 318
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Abstract

Miniaturization is the Advanced Photon technology and devices in recent years, an important development direction in which micro-nano optical waveguide structure is the current research focus. Typically, low-loss dielectric material has excellent optical properties such as, but its light-field constraint by the diffraction limit, and dielectric substrate material is easy on the transmission optical field distribution caused a greater impact. Metal material can be produced by incident wave energy is converted into the free electron metal surface cluster oscillation with deep sub-wavelength dimension constraints, and can transmit optical signals and electrical signals, etc., in the field of micro-nano photonics more and more attention. However, in the light metal material with a strong field at the same time constraints will inevitably produce a high optical loss, signal attenuation and cause serious problems such as heat generation. How to maintain the light field intensity constraints while reducing transmission loss, is the deep subwavelength-scale optical waveguide structure of the key issues facing the world. Based on the above considerations, we propose the use of metal - dielectric micro-nano composite structure (metal support-type micro-nano fiber ring, near-field coupling type metal - dielectric nanowires) to reduce losses and maintain the light field constraint program and successfully apply it the optical sensor, a beam splitter, interferometers, resonators and other micro-nano photonic devices. In the first part of this work, we have developed a micro-fiber metal rods supporting the ring resonator. By adjusting the coupling coefficient of the intrinsic resonator losses balance, to achieve a critical coupling state near the critical point of about 30dB extinction ratio, indicating that the optical waveguide for the micro-and nano media, the use of a composite metal support substrate material structure is to reduce the micro-light guiding field influence Napo effective way. 480gm experiments in diameter obtained in the ring resonator quality factor (Q value) reaches 4000 or more, while, can be precisely adjusted by the current characteristics of the resonant cavity. Examples of the applications of the composite structure, we studied the class resonator in the refractive index of the liquid optical sensing. By measuring the displacement of the cavity resonant peak refractive index change of their environment, we measured the low-concentration aqueous solution and a high concentration of alcohol of the refractive index of the aqueous glycerol solution, the refractive index measurement sensitivity of 1.1 × 10-4, respectively, and 1.8 × 10 - 5, show that such composite resonator can be used for both low and high concentration of the liquid refractive index sensing, high stability, high sensitivity, wide dynamic range and other advantages. In the second part of this work, we propose through the metal - dielectric nanowires near-field coupling, to achieve strong binding and low loss composite photonic structure of the program. Mode field through the dielectric waveguide structure with the metal surface plasmon transmission mode field overlap sufficiently to achieve a fiber satisfied, ZnO nanowires with high efficiency Ag nanowires directly coupled. For example, by coupling length of 220nm, we achieve a single polarization direction of the 650nm wavelength light from the ZnO nanowires of Ag nanowires coupling efficiency of up to 82%. In addition, we also implemented a multi-ZnO nanowires while stimulating root Ag nanowire surface plasmon wave coupling. On this basis, we used Ag-ZnO nanowire composite micro-nano structure, to achieve a polarization beam splitter, Mach-Zehnder interferometer and ring resonator and other micro-nano photonic devices. The coupling length of 200nm order polarization beam splitter, the extinction ratio is about experimental measurements 12.7dB; 58μm scale for Mach-Zehnder interferometer, observe significant interference spectrum; the scale of the composite ring resonator 36gm cavity, Q value reached more than 500, showing the metal - dielectric composite structure in the development of new micro-nano photonic devices and low loss while achieving strong constraints and possibilities. Meanwhile, a variety of micro-and nano-scale functional composite materials, but also for efficient metal surface plasmon excitation, the metal structure loss compensation and active amplification, ultrafast optical modulation, high sensitivity sensor and the cavity quantum electrodynamics research applications provides a promising approach.

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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Photonics technology,laser technology > Optical waveguide and integrated optics > Integrated optical devices
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