Browsing by Subject "Quality factor"

Now showing 1 - 3 of 3

Open Access
Enhanced electro-optic modulation of LiNbO3-based photonic crystal cavities with dual mode and polarization operation
(TUBITAK, 2017) Baǧcı, F.; Kurt G.; Akaoǧlu, B.; Özbay, Ekmel
A high output transmission and high quality factor, compact LiNbO3 -based Fabry-Perot-type photonic crystal cavity is reported that can be used in electro-optical modulators at optical communication wavelengths. The electro-optic effect is 123 times enhanced as compared to the bulk material as a result of the slow light effect. The transmission wavelength is found to depend linearly on the applied voltage with 1.2 nm/V modulation sensitivity. Moreover, an externally switchable dual mode regime with high quality factors and transmissions is realized. High transmissions and high quality factors are also obtained for both transverse-electric and transverse-magnetic polarizations simultaneously. © 2017 TÜBITAK.
Open Access
Grating based plasmonic cavities
(2009) Şenlik, Servet Seçkin
Surface plasmon polaritons are dipole carrying electromagnetic excitations occur- ing at metal-dielectric interfaces. Metallic periodic structures exhibit modi¯ed transmission and re°ection spectra owing to the interaction of propagating SPPs with the periodicity. These periodic surfaces are used to demonstrate localiza- tion of propagating SPPs. Thin metallic ¯lms surrounded by Bragg re°ectors, selective loading of biharmonic metallic surfaces and Moire patterns are used to demonstrate plasmonic cavity formation. The quality factor, Q, a characteristic value that indicates rate of energy loss relative to the stored energy in the cavity is a crucial parameter for classifying these cavities. It was proposed that the Q factor should strongly depend on the surface geometry. However, there was not a sytematic study on the Q factor of these cavity structures. In this work, we report on a comparative study of grating based plasmonic band gap cavities. Numerically, we calculate the quality factors of the cavities based on three types of grating surfaces; uniform, biharmonic and Moirµe surfaces. Experimentally, we demonstrate the existence of plasmonic cavities based on uniform gratings. E®ective index perturbation and cavity geometries are obtained by additional dielectric loading. Furthermore, we fabricate 2D plasmonic structures, observe plasmonic band gaps in the symetry axis and propose cavity geometries for this structure.
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.