The Study Of MZI Electro-optic Switches Based On Polymer Materials

With the rapid development of information and data, we has entered the big dataera. The transmission capacity and transmission bandwidth of the traditionalcommunication system is unable to guarantee the transmission of the big datasmoothly. At the same time the optical fiber communication technology with a largertransmission capacity and higher bandwidth develops rapidly, which graduallyreplaced the traditional communication technology to be one of the important meansof data transmission. In addition, based on optical fiber transmission medium, theoptical fiber communication technology also has a higher electromagneticinterference resistance and lower error rate. The information transfer process ofcurrent optical communication system is mainly include the following three steps:firstly, the analog signal or digital pulse signal is added on the light source for electro-optic transform modulation, and then the modulated light waves transmit along theoptical fiber to the receiving end, finally inverse transformation was carried out by themodem photoelectric, then detect and recovery it into electrical signals, that is thetransmission process of information is based on the electrical signal. Thistransmission process can’t use of network resources reasonably. In order to improvethe utilization of network resources, the concept of all-optical network was putforward. All-optical network has higher reliability and faster transformation speed forit saves plenty of light-electric-light conversion equipment. Wavelength divisionmultiplexing (WDM) technology was proposed and used to realize the expansion ofoptical network, in which the optical switch array plays an important role. Moreover,the optical switch is the key technology of the optical add-drop multiplexer(OADM)and optical cross connection. With its high electro-optical/thermal optical coefficient,small dielectric constant, variety and the advantages of easy integration, the polymermaterials become the ideal material of optical switch.In this paper, we studied the fabrication and test process of polymer-basedelectro-optic switch in detail. The electro-optic switches we fabricated were all basedon the Mach-zehnder interferometer(MZI) waveguide structure. A series of relatedresearch was carried out around the electro-optic switch. The main contents includethe following servial parts:(1) We synthesized a kind of organic/inorganic hybrid electro-optic material, andthe corresponding characterization were done by atomic force microscopy and ellipsometer. Because the thickness of the hybrid electro-optic thin film, according tothe characteristics and combining the material’s refractive index, we prepared theelectro-optic switch based on the MZI waveguide structure with SU-82005, in orderto decrease the leakage loss, we optimized the structure of the device. Finally,weprepared the quasi rectangle electro-optic switch with SiO2as the substrate material,hybrid electro-optic material DR1/TiO2-SiO2as the waveguide core layer, SU-82005as the guide core layer, independently synthesised P (MMA-GMA) as thecladding material. The structure of the electrod we selected was the co-planarwaveguide (CPW). Then we tested the fabricated device, under the frequency of50KHz we got the sinusoidal signal response waveform.(2) We synthesized another doped electro-optic material DR1/SU-8, and somenecessary characterizations was carried out, then fabricated the reverse ridge typeelectro-optic switch based on CPW electrode. We select this type because it is easierto achieve the single-mode transmission compared with other structure, which canreduce the loss of multiple-mode interference. In order to reduce the influence of themiscibility of the layer, we choose the uv-curable adhesive NOA73as the claddingmaterial, in order to reduce light transmission loss, we also studied the etchingconditions of NOA73groove with inductively coupled plasma etching (ICP) which isa dry etching technique. Based on the optimized parameters, we realized the goodetching of NOA73groove, and at last we fabricated the electro-optic switch based onCPW electrode with the material system of DR1/SU-8and NOA73successfully.Good sinusoidal signal response waveform was observed under the frequency of10MHz, while the insertion loss was18dB.(3) We also studied the polymer-based electro-optic switch with microstrip line(MSL) travelling-wave electrode with the same material system. The electro-opticswitch based on the CPW electrode structure has a lower modulation efficiency for itssmall lightning overlap integral factor (г), so the half wave voltage (Vπ) is higher. Inorder to improve the modulation efficiency, we select the MSL electrode structureinstead of CPW electrode structure, for the MSL electrode structure has a bottomelectrode, therefore we prepared the alloy electrode, that is the Au-Si alloy on Sisubstrate. After optimized the alloy conditions,we get the alloy surface root meansquare roughness (RMS) was40nm, the resistivity was2.24μ· cm. We alsocharacterized the alloy with X ray diffraction (XRD) and Energy dispersivespectrometer (EDS). In order to measure the bandwidth of the alloy electrode, a pairof microwave probe was prepared, and we measured the electrode bandwidth of5.2 GHz. We also tested the fabricated electro-optic switch, good electro-optical responsesignal was observed under the frequency of50KHz, and the response time less than10μs.