Yekpare ve melez yalıtkan üstü silisyum tümleşik optik aygıtlar

ABSTRACTMONOLITHIC AND HYBRIDSILICON-ON-INSULATOR INTEGRATED OPTICALDEVICES˙Isa KiyatPhD in PhysicsSupervisor: Prof. Dr. Atilla AydınlıAugust, 2005Silicon, the basic material of electronics industry is rediscovered nowadays forits potential use in photonics and integrated optics. The research activity insilicon integrated optics have been speeding up during the last decade and evenattracting interest of leading industrial companies. As a contribution to this worldwide effort, we have designed, fabricated and characterized a class of monolithicand hybrid silicon integrated optical devices. These devices were realized onhigh-quality silicon-on-insulator (SOI) wafers. Beam propagation method (BPM)based simulations and analytical calculations were employed for the design.We have demonstrated for the first time an SOI device that splits light intoits TE and TM components. An SOI rib waveguide becomes birefringent as itssize reduced. This idea is used to design and fabricate a directional coupler po-larization splitter based on geometrical birefringence. The device uses 1 µm sizedSOI waveguides. This compact device (only 110 µm in length) shows extinctionratios larger than 20 dB.SOI waveguides with the same geometry was used to realize a batch of singleand double bus racetrack resonators having radii in the range of 20 to 500 µm.Design of these racetrack resonators are presented in detail. The bending lossand coupling factor calculations were performed using BPM. During the designand analysis of waveguide resonators, we proposed a novel displacement sensorthat can be used for scanning probe microscopies. The sensor operates by meansof monitoring the changes in transmission spectrum of a high finesse micro-ringresonator due to stress induced by displacement. Operation principles and sensi-tivity calculations are discussed in detail.SOI resonators with quality factors (Q) as high as 119000 have been achieved.ivvThis is the highest Q value for resonators based on SOI rib waveguides to date.Finesse values as large as 43 and modulation depths of 15 dB were observed.Free spectral ranges increased from 0.2 nm to 3.0 nm when radius was decreasedfrom 500 to 20 µm. The thermo-optical tunability of these resonators were alsostudied. A high-Q racetrack resonator is used to develop a wavelength selectiveoptical switch. The resonator was thermo-optically scanned over its full freespectral range applying only 57 mW of electrical power. A low power of 17 mWwas enough to tune from resonance to off-resonance state. The device functionedas a wavelength selective optical switch with a 3 dB cutoff frequency of 210 kHz.We have also demonstrated wavelength add/drop filters using the same racetrackresonators with double bus. Asymmetric lateral coupling was used in order toget better filter characteristics. Filters with crosstalks as low as -10.0 dB andQ-factors of as high as 51000 were achieved.Finally, we introduce the use of a layer transfer method for SOI wafers. Sucha layer transfer results in the possibility of using the back side of the silicon layerin SOI structure for further processing. With this method, previously fabricatedSOI waveguides were transferred to form hybrid silicon-polymer waveguides. Ben-zocyclobutene (BCB) polymer was used as the bonding agent. The method is alsoapplied to SOI M-Z interferometers to explore the possibilities of the technology.We additionally studied asymmetric vertical couplers (AVC) based on polymerand silicon waveguides and fabricated them using a hybrid technology.Keywords: Integrated optics, Silicon-on-insulator technology, Optical waveguides,Polarization splitters, Ring resonators, Racetrack resonators, Displacement sen-sors, Wavelength add-drop filters, Thermo-optical effect, Wavelength selectiveoptical switch, Hybrid integration, Wafer bonding, Mach-Zehnder modulator,Asymmetric vertical coupler.