Student Project Abstracts 2005 - Pluto - University of Washington

areorient themselves with the electric field., mer are isrefractive the internal index incident of theangle EO polymer, of the light and _After poling another glass slide with ITOhlymerof going is thethrough internalthe incident device.Theof waves the light inand DBR is placed on top of the EOe, ch aofphase goingare through reinforced ELECTRO-OPTIC the device. through PROPERTIES The constructive waves OF HYBRID in SOL-GEL MATERIALS IN FABRY-PEROT MODULATORSpolymer and electrical wires are connectedte, d a a interference, phase are reinforced resultingthrough strong constructive narrowWhere λ is the wavelength of the incident wave, l is the with the electric to each field. ITO After layer. poling another The layers glass slide are with thenITOuted and a transmission interference, bands resulting that in vary strong depending narrowthickness of the film, n is the refractive index of the EO polymer, and DBR is clamped placed on top andof epoxy the EO is polymer applied and to electrical seal the wiresbuted ror. upon transmission the multiple bands factors that varyshown dependingand θ is the internal incident angle of the light going through the are connected device. to each ITO layer. The layers are then clamped andirror. upon the ). multiple They factors include filmindevice. The waves in phase are reinforced through constructive epoxy is applied to seal the device.thickness, change ). in refractive They include index due filminterference, resulting in strong narrow transmission bands thattothickness, EO effect, change and surface in refractive roughness. index In duevary depending upon the multiple factors shown in Equation (1).general to EO transmission effect, and surface will occur roughness. wheneverInThey include film thickness, change in refractive index due to the general phasetransmission shift satisfies will the occur following wheneverEO effect, and surface roughness. In general transmission will equation: the phase shift satisfies the followingSol-gel filmoccur wheneverequation:the phase shift satisfies the following equation: ; ;where m = any integer where m = any integer Equation 2. where m = any integerA typical wavelength versusA typical transmission wavelength Aspectra versus typical transmission illustrating wavelength spectra thisillustratingversusthis is shown transmission in in Figure 3.below. illustrating this isshown in change below.change in in the the piezo piezo (mechanical) forces acting acting upon upon the the material.Figure 4. Corona Poling Apparatusd inThe resonance wavelength and thesed s asinshift in in that wavelength are measured byusing a broadband METHODSsource which outputsons ticalasIndium Indiumtintin oxide, oxide, a a transparentthrough a fiber collimator into the Fabry-The resonance wavelength and the shift in that wavelengthptical theconductive conductive material material acts acts as asthe theelectrode electrodeininPerot Perot Etalon.Light that is transmittedthethedevicedeviceandandisisthethefirstfirstlayerlayerdepositeddepositedh theare measured fromfromthetheby cavitycavity using isisfocused a broadband ontoonto asourcesinglesingle which outputsontoontothetheglassglasssubstrate.substrate.ThenThenthetheDBRDBRthrough modemodea fiber fiberfibercollimator detectordetectorinto whichwhich leadsthe Fabry-Perot leadstoto aEtalon. Light thatthelayerlayerisiscoatedcoatedonontoptopfollowedfollowedbybythetheopticalopticalspectrumspectrumanalyzeranalyzer (OSA).(OSA).TheTheTCBD sol-gel. The TCBD sol-gel isde thetransmitted from the cavity is focused onto a single mode fiberghlyTCBD sol-gel. The TCBD sol-gel is OSA measures the wavelength while theprepared and spin coated at varying speedsOSA measures the wavelength while theighlyprepared and spin coated at varying speedsdetector applied which leads voltage to a is optical varied spectrum letting analyzer the (OSA). Thenceto set the thickness of the EO polymerapplied voltage is varied letting theto set the thickness of the EO polymerwavelength shift be directly observed.renceOSA measures the wavelength while the applied voltage is variedonlyfilm. After baking, this layered material is wavelength shift be directly observed.film. After baking, this layered material isBy switching the broadband source to corona poled above the glass transition By switching the broadband source to aonlyletting the narrowband, wavelength tunable shift be laser directly the extinction observed.eingcoronatemperaturepoledatabovea highthevoltage.glass transitionPoling is narrowband,beingBy ratio switching and the dynamictunablebroadband modulationlaser the extinctionsource to ofa the narrowband, tunablewilltemperaturedone to orientat athehighchromophorevoltage. Polingmoleculesis ratiosampleandcandynamicbe measured.modulationTheoflaserthes will Figure 3. Typical Transmittance done Spectra Fabry Perot Etalon laser the extinction ratio and dynamic modulation of the sampleofandtoforceorientnon-centro-symmetrythe chromophore moleculesin the sample propagates canthrough be measured.collimator, The continues laserAdapted from Lambda and film. Research force The Optics non-centro-symmetry combination Inc. of temperatures in thee ofcan be measured.propagates through thethrough The device laseracavity collimator,propagates and finally continuesthrough the a collimator, continuesthroughthefilm. above The thecombination glass transition of temperatures temperature, throughet in thetransmitted thethe devicelight device iscavityfocused cavity andandontofinally finallythe fiber theabove the transmitted lightWhen whichthe causes glass thetransition Si/SiO2 sol temperature, gel matrix to transmitted detector. The light dynamic is focused modulation onto the can fibervoltage is applied to the material a shift in the resonancewavelength occurs and relax, correlates to the change in refrac-are theinwhich is focused onto the fiber detector. The dynamic modulation can relax, causes and the theapplication Si/SiO2 sol of gel a high matrix electric to detector. observedThe by dynamic switchingmodulation the DC voltage can beirror s theAdapted from Lambda fieldand Research causes the applicationOptics Inc. the highly of a high polarizable electricbe observed observed source by to switching byAC switching by the inserting DC thevoltage DC a function voltage source to AC by insert-a functionfieldtive index (∆n) due Adapted to the from electro-optic chromophore causes theLambda Research effect molecules highlyOptics and Inc. the change topolarizablerotate in and source generator and ACchanging by inserting to a photo a function detectorions irrorchromophore orient themselves molecules with the to electric rotate field. andinggeneratorgenerator and changing to a photo detector whichwhich inputs and changing into a digital to a photo oscilloscope. detectorthickness (∆l) due to a change in the piezo (mechanical) forcesctions When voltage is applied orient After to themselves poling material another withglass the a electric slide with field. ITOinputs into which Seea digital inputs oscilloscope. into a digital below See oscilloscope. for Figures testing5, 6, and 7 belowacting shift upon When in the the voltage material. resonance is applied After wavelength andpoling DBR to the another is material placed occurs glass onaslide top of with theITOEOfor testing See schematics. below for testingand shift correlates in the resonance and polymerto the change wavelength DBR and is placed electricalin refractive occurs onwires top are of connected the EO schematics.polymer to eachand ITOelectrical layer. wires The layers are connected are then index and DEVICE correlates () due ASSEMBLY to to the toelectro-optic clampedchangeeach ITO / and POLING inlayer.refractiveepoxy effect The is applied layerstoare seal thenindex () due to the electro-optic effect Indium and the tin change oxide, a in transparent thickness clamped device. andconductive () epoxy due material to is applied a to seal theacts asand the change in thickness device. () due to athe electrode in the device and is the first layer deposited onto the glass substrate. Then the DBR layeris coated on top followed by the TCBD sol-gel. The TCBD sol-gel is prepared and spin coated 1 No. 1 at Summer varying 2004 speeds to set the thickness Sol-gel of filmthe EO polymer film. AfterSummer baking, 2004 this layered material Sol-gel is corona film poled above the glassFigure 5. Shift Measurement Schematicol. 1 No. 1 transition temperature at a high voltage. Poling is done to orient the chromophore molecules and force non-centro-symmetry inthe film. The combination of temperatures abovethe glass transitiontemperature, which causes the Si/SiO 2 sol gel matrix to relax, and the application of a high electric field causes the highly polarizablechromophore molecules to rotate and orient themselves Figure 6. Extinction Measurement Schematic36 CMDITR Review of Undergraduate Research Vol. 2 No. 1 Summer 2005CMDITR Review of Undergraduate Research Vol. 1 No. 1 Summer 2004 whiSeeschCMDITR Review of Undergrad