Browsing by Author "Chou, Chia-Sheng"

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A simple model for cavity enhanced slow lights in vertical cavity surface emission lasers
(2008-04-01)
Chou, Chia-Sheng
;
Lee, Ray-Kuang
;
Peng, Peng-Chun
;
Kuo, Hao-Chung
;
Lin, Gray
We develop a simple model for the slow lights in vertical cavity surface emission lasers (VCSELs), with the combination of cavity and population pulsation effects. The dependences of probe signal power, injection bias current and wavelength detuning for the group delays are demonstrated numerically and experimentally. Up to 65 ps group delays and up to 10 GHz modulation frequency can be achieved at room temperature at a wavelength of 1.3 mu m. The most significant feature of our VCSEL device is that the thickness of the active region is only several micrometers long. Based on the experimental parameters of quantum dot VCSEL structures, we show that the resonance effect of the laser cavity plays a significant role in enhancing the group delays.
Multicast Routing and Channel Assignment in Wireless Mesh Networks
(2009)
Chou, Chia-Sheng
;
Chen, Chien
;
Chen, Ying-Yu
;
Jan, Rong-Hong
;
Hsieh, Cheng-Chung
This paper studies the problem of multicast routing and channel assignment in multi-channel and multi-interface wireless mesh networks. The advantage of the wireless broadcast's nature is used to reduce interference and improve network throughput. The employed network model is first described. Next, a heuristic channel assignment algorithm that makes use of the wireless broadcast's advantage is presented. Simulation results reveal that the proposed heuristic algorithm can reduce interference and increase the network throughput in multi-channel multi-interface wireless mesh networks.