Browsing by Subject "Q-factor"

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Open Access
Circular high-Q resonating isotropic strain sensors with large shift of resonance frequency under stress
(2009) Melik, R.; Unal, E.; Perkgoz, N.K.; Puttlitz, C.; Demir, Hilmi Volkan
We present circular architecture bioimplant strain sensors that facilitate a strong resonance frequency shift with mechanical deformation. The clinical application area of these sensors is for in vivo assessment of bone fractures. Using a rectangular geometry, we obtain a resonance shift of 330 MHz for a single device and 170 MHz for its triplet configuration (with three side-by-side resonators on chip) under an applied load of 3,920 N. Using the same device parameters with a circular isotropic architecture, we achieve a resonance frequency shift of 500 MHz for the single device and 260 MHz for its triplet configuration, demonstrating substantially increased sensitivity. © 2009 by the authors.
Open Access
Submicron size all-semiconductor vertical cavities with high Q
(Institute of Electrical and Electronics Engineers Inc., 2019) Demir, Abdullah; Apaydın, D.; Kurt, H.
The miniaturization of lasers promises on-chip optical communications and data processing speeds that are beyond the capability of electronics and today's high-speed lasers. Lasers with low-power consumption are one of the most important parts in creating a photonics integrated architecture. This requirement was the motivating force behind the development of small laser and nanolasers. Here, we propose a new method that could be utilized to fabricate such a laser. Oxide-VCSELs require strict control of the oxidation process with significantly reduced reliability for small size, and micropillars have degraded Q with fabrication artifacts for submicron diameter pillars. We propose to use a phase-shifting current-blocking (PSCB) layer serving dual function for a nanocavity device (Fig. 1a) providing both optical- and electrical-confinement via lithographically defined and selectively-biased buried structures. Phase-shifting leads to optical-confinement tuning by layer thickness control and current-blocking provides electrical-confinement. By modifying the dimensions of these layers, the confinement can be tuned by lithographic means. We studied the electromagnetic wave propagation and analyzed the quality factor (Q) of these cavities based on 3D finite difference time domain (FDTD) calculations.