Browsing by Author "Tseng, Chung-Chuan"

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Modal properties and thermal behaviors of high quality factor quasi-photonic crystal microcavity with different central post sizes
(2008-08-18)
Lu, Tsan-Wen
;
Lee, Po-Tsung
;
Tseng, Chung-Chuan
;
Tsai, Yi-Yu
;
光電工程學系
We investigate the variations of modal properties of 12-fold quasiphotonic crystal microcavities sustaining whispering-gallery (WG) mode with different central post sizes both in simulations and experiments. We realize our design by a series of dry- and wet-etching processes. WG mode lasing actions are obtained with high quality (Q) factor of 8,400 from microcavity with effective post size 420 nm in diameter. Loss and thermal behaviors are analyzed by measured Q factors, thresholds, and rolling-off effects from light-in light-out curves of microcavities with increased post size. By finite-element simulations, we also address the heat sink improvement due to presence of larger central post that is observed in measurements.
Photonic crystal circular-shaped microcavity and its uniform cavity-waveguide coupling property due to presence of whispering gallery mode
(2007-07-23)
Lee, Po-Tsung
;
Lu, Tsan-Wen
;
Yu, Chia-Ming
;
Tseng, Chung-Chuan
;
光電工程學系
In this report, we investigate a photonic crystal circular- shaped microcavity ( removing seven air holes) sustaining whispering- gallery mode ( WGM) by shifting the 12 nearest air holes according to the concept of cavity- shaping in micro- disk and micro- gear lasers. The WGM modal characteristics are investigated by three- dimensional ( 3D) finite- difference time- domain ( FDTD) simulations. From well- fabricated devices and simulated results, we obtain and identify WGM single- mode lasing with low threshold and high measured quality factor. By inserting additional waveguides, we also investigate its uniform coupling behaviors in different waveguide- cavity- waveguide geometries in both FDTD simulations and experiments. (c) 2007 Optical Society of America.