Research And Fabrication For Integrated Optical Waveguide Interleaver Module Based On Fluorinated Photopolymer

With the prosperous development of optical communications, the demand forbandwidth becomes even more urgent. In order to speed up the construction ofultra-long distance optical communication systems with ultrahigh bit rate transmission,optical interleaver has attracted increasing attention and become a research hotspot inthe dense wavelength division multiplexing(DWDM) technology. Compared with thecommon wavelength division multiplexing techniques, smaller channel spacing ofoptical interleaver makes it more satisfactory DWDM technology for the modernoptical fiber communication system. And the use of optical interleaver in the DWDMsystem not also can effectively reduce the burden of wavelength spacing requirementsfor the subsequent devices, but also can achieve the purpose of improving thetransmission capacity. There are many ways to realize the optical interleaver, of whichthe interleaver based on the arrayed waveguide grating (AWG) has many advantages.For example, it has multiple channels, compact structure, small crosstalk and signaldistortion, good stability, besides, it is able to realize hybrid integration chip withkinds of optical waveguide devices. Therefore, the AWG-based interleaver hasbecome the research hotspots of the interleaver devices.This thesis concentrates on the design and fabrication of integrated opticalwaveguide interleaver module. The Waveguide structure parameters were carefullycalculated and optimized. The control electrode was introduced into part of theintegrated module to achieve the wavelength-channel selective function as well ascompensate AWG for the central wavelength drift caused by fabrication process. Inthis paper, the complementary metal oxide semiconductor (CMOS) integratedcircuit(IC) fabrication techniques, such as spin coating, lithography, etching andvacuum evaporation, were used to fabricate the waveguide and the electrodes. Themain work of this thesis can be summarized as follows:(1). An integrated interleaver module is proposed, and it is composed of cascadedAWGs-based wavelength-channel selector monolithically integrated with multimodeinterferometer (MMI) and Mach-Zehnder interferometer (MZI) switches. Channelspacing of the cascaded two AWG was set to be0.8nm and1.6nm respectively to divide the composite signal light into two parts, odd wavelength and even wavelength.In addition, the control electrode is introduced into the array waveguide gratings andoptical switches, while its structure was designed and optimized in detail in order toachieve precise control of temperature on local waveguide region. And then thechannel-selection function can be obtained through the thermos-optic effect.(2). An organic-inorganic graft modification PMMA materials was successfullysynthesized. This kind of organic-inorganic hybrid material has many advantages,such as robustness, largely adjustable refractive index and TO coefficient, andcompatibility with established silicon manufacturing procedures, while thesecharacteristics benefit the preparation of thermos-optic devices. Besides, thepreparation parameters for an novel fluorinated photosensitive polymer material wereimproved through repeated experiments, and straight waveguide with goodmorphology was obtained using the photolithography method. The waveguidetransmission loss of the fluorinated material is much smaller compared with thecommon used SU-8photoresist material.(3). The integrated interleaver module was prepared utilizing fluorinated photoresistpolymer and organic-inorganic composite material as waveguide core and claddingmaterials respectively. The CMOS IC fabrication process was used to fabricate thewaveguide and electrode. The insertion loss at each channel is from5.55dB to6.86dB.The total resistance for the two AWG was tested to be800Ω. When row-vectoradjustment of the wavelength transfer matrix(WTM) of these two AWG was achieved,the heat-driven powers are10.5mW and6.5mW respectively. The extinction ratio ofthe thermo-optic switch was measured about18.2dB with2.2V bias, and he appliedelectric power as the switching power is actually8.6mW.