Browsing by Author "Hsu, C. W."

Now showing 1 - 8 of 8

Cost-Effective Direct-Detection All-Optical OOK-OFDM System With Analysis of Modulator Bandwidth and Driving Power
(2015-08-01)
Hsu, C. W.
;
Chow, C. W.
;
Yeh, C. H.
;
光電工程學系
;
光電工程研究所
Optical orthogonal frequency-division multiplexing (OFDM) with advanced modulation format [e.g., quadrature amplitude modulation (QAM) and quadrature phaseshift keying (QPSK)] provides many transmission advantages. As the OFDM data rate is limited by the electronic digital-to-analog (DAC) and analog-to-digital (ADC) integrated circuits, an all-optical technique (i.e., all-optical OFDM) is used to construct an OFDM symbol; hence, it can provide a significant improvement in transmission capacity. In this work, we propose and demonstrate a cost-effective 275-Gb/s direct-detection all-optical OFDM system for access or data center networks. As all wavelength channels (11 wavelengths in the experiment) are produced by one laser source, only the temperature control of one master laser is enough. In addition, each wavelength channel in the all-optical OFDM signal is encoded using on-off keying (OOK) modulation format; the traditional generation and detection circuits used in the transmitter (Tx) and receiver (Rx) of the present passive optical network can still be used. We also numerically analyze the requirements of the opt-comb-MOD (modulator used to generate the optical comb source) and the data-MOD (modulator used to generate the OOK data) in the system.
DEVICE MODELING OF A MICROMORPH TANDEM SOLAR CELL USING AMPS-1D
(2010)
Huang, J. Y.
;
Hsu, C. W.
;
Shieh, Jia-Min
;
Yu, Peichen
;
光電工程學系
This work first theoretically optimize the amorphous (a-Si:H) and the microcrystalline (mu c-Si:H) devices characteristics, and then perform studies for micromorph tandem solar cells. The studies calculated by AMPS-1D show that the TCO work function has obvious influence on the open-circuit voltage. Moreover, the power conversion efficiency of an a-Si:H cell is optimized by changing the absorber's layer thickness and mobility gap. Furthermore, a critical doping concentration of mu c-Si:H films limiting the barrier height of a grain boundary (GB) is observed. After optimizing sub cell mutually, we combine the individual junctions to construct a micromorph cell which has an efficiency of 9.24%.
Enabling Technologies and Signal Processing for NG-PON2 and Future WDM-PON (Invited)
(2013-01-01)
Chow, C. W.
;
Sung, J. Y.
;
Hsu, C. W.
;
Yeh, C. H.
;
光電工程學系
Silicon-based optical components are now mature technologies; and they can be used in the time-and-wavelength-division-multiplexed passive-optical-network (TWDM-PON) optical networking unit (ONU)to increase the level of integration for cost reduction. We will also discuss the further migration form the NG-PON2 to the future pure WDM-PON.
Integrated SOT-based Receiver Module for TWDM-PON
(2016)
Hsu, Y.
;
Wu, X. R.
;
Wei, L. Y.
;
Xu, K.
;
Hsu, C. W.
We demonstrate a SOl-based integrated receiver (Rx) module for the TWDM-PON. The downstream can be de-multiplexed by a tunable de-multiplexer using cascaded silicon-micro-ring and each channel is received by germanium-on-silicon photodiode.
LED-based Visible Light Communication Integratable to Main Power Line Network with Optical Background Noises Mitigation
(2014-01-01)
Chow, C. W.
;
Yeh, C. H.
;
Hsu, C. W.
;
Huang, P. Y.
;
Liu, Y. F.
Optical background noises from conventional fluorescent light sources can significantly affect the performance of the light emitting diode (LED)-based visible light communication (VLC). We demonstrate a LED-based VLC system that is integratable to the main power line network. By using orthogonal-frequency-division-multiplexing (OFDM) format, the optical background noises can be mitigated. Experimental results show that by adjusting the number of OFDM subcarriers, the influence of optical background noises can be significantly mitigated.
Mitigation of LED Nonlinearity Using Adaptive Equalization for Visible Light Communications
(2017-01-01)
Hsu, C. W.
;
Hsu, Y.
;
Chen, G. H.
;
Wei, L. Y.
;
Chow, C. W.
We demonstrate using bit-loading orthogonal-frequency-division-multiplexing (OFDM) and adaptive Volterra equalization to mitigate the light-emitting-diode (LED) nonlinearity; hence the data rate of LED based visible-light-communication (VLC) can be increased to > 700 Mbit/s.
Optical filter analyses for demultiplexing all-optical OFDM transmission systems
(2015-08-01)
Sung, J. Y.
;
Hsu, C. W.
;
Su, H. Q.
;
Chow, C. W.
;
Yeh, C. H.
Using a single optical filter to demultiplex the all-optical orthogonal frequency-division multiplexing (OFDM) system was regarded as cost-effective and simple. Here, an all-optical OFDM signal demultiplexer using sinc transfer function was analyzed. The performance difference for using optical demultiplexers with different transfer functions was also compared and discussed. Within 20 km transmission, the sinc optical filter providing orthogonality between neighbor optical subcarriers can improve the signal performance by reducing the inter-carrier interference. After 20 km transmission, the signal performance degradation may mainly be dominated by dispersion for 10 Gb/s channel capacity; hence the advantage of sinc filter becomes negligible. These analyses provide the idea for how to choose the optical demultiplexer to integrate the whole optical fast Fourier transform circuit and optical sampling circuit into a single filter. This can effectively reduce the system cost and complexity.
Wired and wireless convergent extended-reach optical access network using direct-detection of all-optical OFDM super-channel signal
(2014-12-15)
Chow, C. W.
;
Yeh, C. H.
;
Sung, J. Y.
;
Hsu, C. W.
;
光電工程學系
We propose and demonstrate the feasibility of using all-optical orthogonal frequency division multiplexing (AO-OFDM) for the convergent optical wired and wireless access networks. AO-OFDM relies on all-optically generated orthogonal subcarriers; hence, high data rate (> 100 Gb/s) can be easily achieved without hitting the speed limit of electronic digital-to-analog and analog-to-digital converters (DAC/ADC). A proof-of-concept convergent access network using AO-OFDM super-channel (SC) is demonstrated supporting 40 - 100 Gb/s wired and gigabit/s 100 GHz millimeter-wave (MMW) ROF transmissions. (C) 2014 Optical Society of America