Browsing by Author "Dagli, N."
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Item Open Access Characterization of multilayer self-organized InAs quantum dot embedded waveguides at 1.3 and 1.5 μm(IEEE, 2007) Akca, B. Imran; Dana, Aykutlu; Aydınlı, Atilla; Rossetti, M.; Li L.; Fiore, A.; Dagli, N.In this paper, we characterized the electro-optic coefficient and loss of multilayer InAs quantum dot laser structures at 1309 and 1515 nm. Quantum dot waveguides were grown by molecular beam epitaxy, where the active region is formed by three or five layers of self-assembled InAs QDs. Loss characterization were carried out by using a 1.3 μm light from a thermally tunable laser. Transmission through the device was recorded as a function of wavelength. Loss coefficient is found to be wavelength and bias voltage dependentItem Open Access A Compact Silicon-on-insulator Polarization Splitter(IEEE, 2005) Kiyat, I.; Aydınlı, Atilla; Dagli, N.A compact directional coupler-based polarization splitter is designed and realized using silicon-on-insulator (SOI) waveguides. Even though silicon does not have any material birefringence, the high index contrast obtained in the SOI platform and reduced waveguide dimensions makes it possible to induce significant birefringence. Polarization splitting is achieved by making use of this geometry-induced birefringence. In this work, we demonstrate polarization splitting in devices as short as 120 gm. Even smaller devices can be made using submicron-thick Si waveguides.Item Open Access Electric field dependence of modulation in multilayer InAs quantum dot waveguides(IEEE, 2007) Akça, Imran B.; Dana, Aykutlu; Aydınlı, Atilla; Rossetti, M.; Li, A.; Fiore, A.; Dagli, N.The low voltage modulation in InAs quantum dot waveguides is observed in this paper. We have measured the electro-optic coefficient in multilayer quantum dot structures far away from resonance and obtained an enhancement compared to bulk GaAs. Electro-absorption measurement results suggest that these waveguides are good candidates for use in electro-absorption modulators such as Mach-Zehnder devices.Item Open Access Filtering characteristics of hybrid integrated polymer and compound semiconductor waveguides(IEEE, 2002) Ozturk, C.; Huntington, A.; Aydınlı, Atilla; Byun, Y.T.; Dagli, N.This paper reports a study on a compact filter fabricated using hybrid integration of compound semiconductors and polymers. A GaAs epilayer is glued onto a polymer channel waveguide forming a highly asymmetrical directional coupler. This approach results in a narrow band filter due to very different dispersion characteristics of the compound semiconductor and the polymer materials. Furthermore, fiber coupling loss has been significantly reduced, since the input and output coupling is done through the polymer waveguide. Filtering characteristics can be engineered by changing the thickness and the length of the semiconductor epilayer. This can be done precisely using etch stop layers and noncritical lithography. The spectral response of such a filter can also be tuned electronically either using the electro-optic properties of the compound semiconductor or the thermo-optic properties of the polymer.Item Open Access High-Q silicon-on-insulator optical rib waveguide racetrack resonators(Optical Society of American (OSA), 2005) Kiyat I.; Aydınlı, Atilla; Dagli, N.In this work, detailed design and realization of high quality factor (Q) racetrack resonators based on silicon-on-insulator rib waveguides are presented. Aiming to achieve critical coupling, suitable waveguide geometry is determined after extensive numerical studies of bending loss. The final design is obtained after coupling factor calculations and estimation of propagation loss. Resonators with quality factors (Q) as high as 119000 has been achieved, the highest Q value for resonators based on silicon-on-insulator rib waveguides to date with extinction ratios as large as 12 dB. © 2005 Optical Society of America.Item Open Access Linear electro-optic coefficient in multilayer self-organized InAs quantum dot structures(IEEE, 2007) Akca, B. Imran; Dana, Aykutlu; Aydınlı, Atilla; Rossetti, M.; Li L.; Dagli, N.; Fiore, A.The electro-optic coefficients of self-organized InAs quantum dot layers in molecular beam epitaxy grown laser structures in reverse bias have been investigated. Enhanced electrooptic coefficients compared to bulk GaAs were observed. © 2003 Optical Society of America.Item Open Access Low-power thermooptical tuning of SOI resonator switch(IEEE, 2006) Kiyat, I.; Aydınlı, Atilla; Dagli, N.A wavelength selective optical switch is developed based on a high-Q racetrack resonator making use of the large thermooptic coefficient of silicon. The racetrack resonator was fabricated using a silicon-on-insulator (SOI) single-mode rib waveguide. The resonator shows a high Q factor of 38 000 with spectral sidelobes of 11 dB down and can be thermooptically scanned over its full free-spectral range applying only 57 mW of electrical power. A low power of 17 mW is enough to tune the device from resonance to off-resonance state. The device functions as a wavelength selective optical switch with a 3-dB cutoff frequency of 210 kHz.Item Open Access Modulation in InAs quantum dot waveguides(Optical Society of America, 2007) Akca, B. Imran; Dana, Aykutlu; Aydınlı, Atilla; Rossetti, M.; Li L.; Fiore, A.; Dagli, N.Modulation in molecular beam epitaxy grown self-assembled InAs quantum dot waveguides have been studied at 1500 nm as a function of wavelength and voltage. Enhanced electro-optic coefficients compared to bulk GaAs were observed. © 2007 Optical Society of America.Item Open Access Modulation of multilayer InAs quantum dot waveguides under applied electric field(Optical Society of America, 2007) Akça, Imran B.; Dana, Aykutlu; Aydınlı, Atilla; Rossetti, M.; Li L.; Fiore, A.; Dagli, N.Electric field dependence of optical modulation in self assembled InAs quantum dot waveguides have been studied at 1300 and 1500 nm. Electro-absorption and electro-optic coefficients of these waveguides have been obtained at both wavelengths. © 2007 Optical Society of America.Item Open Access Polarization characteristics of compact SOI rib waveguide racetrack resonators(IEEE, 2005) Kiyat, I.; Aydınlı, Atilla; Dagli, N.We report on the development of compact optical racetrack resonators on silicon-on-insulator (SOI) rib waveguides. We make use of large-cross-section waveguides instead of photonic wire waveguides. We fabricated resonators with bending radii down to 20 μm and characterized for both transverse-electric and transverse-magnetic polarizations. Different polarization characteristics were analyzed and related to the modal shape of the SOI waveguide. These compact resonators show large free spectral ranges (3.0 nm), high finesse (19), and Q-factor (28 000) values.Item Open Access Study of wet oxidized AlxGa1-xAs for integrated optics(Institute of Electrical and Electronics Engineers, 1999) Bek, A.; Aydınlı, Atilla; Champlain, J. G.; Naone, R.; Dagli, N.An investigation of wet oxidized AlxGa1-xAs layers in integrated optical applications is reported. Refractive index and thickness shrinkage of wet oxidized AlxGa1-xAs layers are measured using spectroscopic ellipsometry. A Cauchy fit to the refractive index is found in the wavelength range between 0.3 and 1.6 μm. The refractive index at 1.55 μm is found to be 1.66±0.01 with little dispersion around 1.55 μm. Very low loss single-mode waveguides with metal electrodes showing very low polarization dependence of loss coefficient are fabricated using wet oxidized AlxGa1-xAs layers as upper cladding. Optical polarization splitters are also designed and fabricated from the same type of waveguides taking advantage of increased birefringence. Designs utilizing wet oxidized AlxGa1-xAs are compared with conventional designs using only compound semiconductor heterostructures.