Investigation Of Electro-Optic Waveguide Devices Based On Poled Polymers

Nowdays, the big data network era has coming, compared with the past, peoplehave increased the demand for data and information greatly, the traditionaltransmission ways of data and information can’t meet the demand of human beings.Therefore, a new way of communication and transporting—optical fibercommunication is coming to the central of the world stage, becoming the master ofthe systems. Optical fiber communication, just as its name implies, optical fiber is themain transmission medium, compared with the traditional communication system ithas the following advantages: high bandwidth, low bit error rate, high ability ofresisting electromagnetic interference, low loss, high speed, etc. In addition, theoptical modulator, switch and its arrays play an indispensable role in wavelengthdivision multiplexing (WDM) technology as the core parts of optical add-dropmultiplexer (OADM) and optical cross connection (OXC). High performanceelectro-optic(EO) switches are widely used in optical fiber communication systems,and optical signal-processing systems. Different materials have been used to fabricateEO switches, including lithium niobate (LiNbO3), gallium arsenide (GaAs), siliconand polymers. However, even for the matured commercial material of LiNbO3, thehigh switching voltage and the phase mismatch between optical wave and microwaveare still obstacles for the future application in wide bandwidth optical communicationsystems. EO polymers have merits of high linearity, comparatively low dielectricconstants for high speed switching, and processing convenience for low costfabrication. The half-wave voltage of polymer electro-optic modulator can be below1V,3dB bandwidth can be up to100GHz, the time response of the polymerelectro-optic switch can achieve the magnitude of ps. Poled polymer electro-opticdevices have become one of the highly competitive core components in widebandwidth optical fiber communication systems.In this paper the detailed simulation, calculation and synthesis of the materials,drawing light rigid and fabrication of the electro-optic devices have been carried on,finally the electro-optic devices have been tested, ideal results are obtained. The maincontents contain the following several parts:1.We design a kind of coplanar waveguide (CPW) electrodes, and then measurethe microwave properties such as S parameters combining the material ofNOA73(Norland Optical Adhesive73) with the vector network analyzer. We get the attenuation constant, phase constant, characteristic impedance, dielectric constantsand so on by means of corresponding calculation and simulation with the S21parameter. And then we design the structure of the buried coplanar waveguideelectrode polymer electro-optic modulator and the rigid of the waveguide, theelectrode. We select the material of NOA73as the cladding layer, DR1/PMMA as thecore layer, then the etching morphology of the electrode and waveguide groove ofNOA73are optimized, getting the optimum parameter of etching the NOA73groove,obtaining the morphology of small bottom roughness and high verticality. Finally, theelectro-optic modulator is tested, the result is well.2. A kind of doped electro-optic polymer material DR1/SU-8has beensynthesised, and the electro-optic coefficient γ33and refractive index are measured. Inorder to limit the absorption of cladding, reduce the loss of the electro-optical switch,improve the efficiency of modulation, we select a kind of ultraviolet-curable adhesiveNOA73as the cladding material. The film-forming property of NOA73has beenobserved, and the atomic force microscope (AFM), refractive index and absorptionhave also been characterized. Then single-mode transmission condition of invertedridge waveguide, variations of effective refractive index of the fundamental modeswith ridge height, variation of optical field distributions in EO layer with slabthickness, variations of effective refractive index of the fundamental modes withwavelength are calculated detailed. The optical power distribution for the modepropagation of Mach-zehnder interferometer (MZI) type electro-optic switch issimulated by the beam propagation method (BPM) software based on micro-strip line(MSL) travelling-wave electrodes. The Scanning electronic microscopy (SEM) of thedevice is characterized after the electro-optic switch being fabricated. Finally, theelectro-optical switch is tested, good square wave signal response waveform isobserved under the frequency of10KHz, the rise time and fall time of theelectro-optic switch are3.199ns and2.559ns respectively.3. We also design and fabricate micro-strip line travelling-wave electrodepolymer electro-optic switch based on surface plasma waveguide structure with thematerials of NOA73and DR1/SU-8. Firstly, we design the structure of the waveguide,Mach-zehnder interferometer, namely the MZI type, then we design the electrodestructure that matches the waveguide. Spin-coating, photolithography and plasmaetching are performed to fabricate electro-optic switch with MSL electrodes. And thenthe device is contact poled, achieving its second order optical nonlinearity. Finally,the electro-optic switch is tested, good square wave signal response waveform is observed under the frequency of10KHz, the rise time and fall time of theelectro-optic switch are578.7ns and645.3ns respectively.