| The booming of the Internet business has changed the status of thetelecommunication industry. Incessant innovations of communication technologiesand networking are keeping changing our way of living, working, and interacting witheach other. Optical fiber communication systems have advantages, such as wide band,big capacity of transmission, low loss of transformation, small error rate, and strongability of anti-electromagnetic interference, etc. Especially the application ofwavelength-division multiplexing (WDM) in optical networking has achievedeffectively the tremendous capacities of the optical transport network. The opticalswitch and its array play an important role in WDM network systems in the aspect ofthe vital functions including optical domain optimizing, routing, protection andself-healing, which is the core technology of optical add/drop multiplexing (OADM)and optical cross-connects (OXC). Polymers have many merits of multipleclassifications, low cost, simple processing, large thermal conductivity, highelectro-optic (EO) coefficient, and fast EO response, which have aroused wideattraction. This paper makes a fundamental research on both thermo-optic (TO)switch and EO switch of silicon-base polymer.As for the TO switch, polymer/silica hybrid waveguide is proposed and adoptedin order to improve the performance of response time. Firstly, this paper introducesproduction mechanism and the related basic theory, including thermo-optic effect,which can interpret the relation between the refractive index and the temperature;thermal conduction and distribution in waveguide, which can reveal the relationbetween the temperature and the heat driving power; switching function is realized inmach zehnder interferometer (MZI) type switch, through which we can understand therelation between the normalized output power and the refractive index.Secondly, combining the virtue of larger TO coefficient of polymer and largerthermal conductivity of silica, polymer/silica hybrid waveguide TO switch isproposed and designed. Because of lager thermo conductivity relative to polymer,silica is utilized as under cladding for accelerating heat release. The switch exhibitslow power consumption and fast response time. By employing the hybrid structurewith the negative photoresist (SU-8) as the core material and silica as the lowercladding, three type switches are fabricated.(1). A polymer-on-silica MZI TO switch is experimentally demonstrated throughthe wet-etching technique to diminish the side wall roughness and decrease thescattering loss. The thickness of claddings is optimized to be minimum under the case of insuring low optical loss. The thin upper cladding is helpful for reducing drivingpower because of small heat loss. Moreover, a thin under cladding can also speed theheat dissipating through silica and substrate, and a short response time can beobtained. Relation between waveguide temperature and electrode heater width iscalculated. The fabricated switch exhibits low power consumption less than4.8mW,high extinction ratio about22.5dB, short rise time about141μs and short fall timeabout87μs. Compared to the reported polymer TO switches, the switching time isreduced by50%.(2). A polymer/silica hybrid2×2directional coupler (DC)-MZI TO switch with ribwaveguide is fabricated using inductively coupled plasma (ICP) technique. Effects ofheat driving power on refractive index and temperature are calculated by solid thermalconduction equation. Under steady state, consumption power is theoreticallycalculated to be6.9mW, and under transient state, the switching time is theoreticallydecided to be107μs and that is as large as174μs of polymer TO switch with samestructure. Experiments exhibit that the switch performs good performance includingfast response time (rise and fall times are106and93μs, respectively), which isshortened by40%compared to that of the switch using polymer as cladding. Theproposed switch also exhibits much lower switching power as7.2mW, due to carefuldesign and optimization on fabrication process.(3). A polymer/silica hybrid2×2multimode interference (MMI) MZI TO switchusing wet-etching technique is experimentally demonstrated. The developed switchexhibits low power consumption of6.2mW, low crosstalk of about-28dB and shortresponse time. The rise time of103μs and fall time of91μs for this hybrid switch areshortened by44.9%and49.4%, respectively, compared to those of the fabricated TOswitch (187and180μs) using polymer as both upper and under claddings.As for EO switch, a bias-free MZI electro-optic (EO) switch is realized throughthe use of an asymmetric Y-branch. Firstly, the paper introduces the related basetheory about EO switch, including the physical mechanism of EO effect, and thedifferent polarization techniques for nonlinear polymer, as well as the direct current(DC) bias function for EO switch efficient work.Utilizing the asymmetric Y-branch splitter and coupler, the bias point is adjustedto be3-dB operation point, which enables the switch to be operated without DC bias.Dye-doped EO polymer DR1/SU-8is synthesized as the core material, which has highglass temperature (Tg=215℃), and possesses favorable performance against thedegradation of EO coefficient resulting from thermal relaxation. The devicefabrication technology and process are described in detail, and the performances aremeasured at the wavelength of1550nm. The insertion loss is decided to be11.9dB.The rise time and the fall time are both measured to be at the level of~10ns under theoperation of a non-step-style square-wave alternating current (AC) signal.
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