Browsing by Author "Lai, YC"

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0.66 mu m InGaP/InGaAlP single quantum well microdisk lasers
(1998-06-01)
Pan, JS
;
Cheng, PH
;
Lee, TD
;
Lai, YC
;
Tai, KC
Visible emitting microdisk lasers with single InGaP/InGaAlP quantum well were demonstrated for the first time. Large spontaneous emission factors beta of 0.12 and 0.08 were observed for 5 and 10 mu m diameter disks, respectively.
A cost-effective fast frequency-hopped code-division multiple-access light source using self-seeded Fabry-Perot laser with fiber Bragg grating array
(2004-11-01)
Peng, WR
;
Peng, PC
;
Lin, WP
;
Hsu, KC
;
Lai, YC
We propose a novel light source for the optical fast frequency-hopped code-division multiple-access scheme using a self-seeded gain-switched Fabry-Perot laser diode (FP-LD) with the reconfigurable fiber Bragg grating array (FBGA). The embedded FBGA in the external cavity loop encodes the input pulses both temporally and spectrally. Before feeding back into the FP-LD, the encoded optical pulses propagate the FBGA with reverse direction and are again temporally combined. With the corporation of the variable fiber delay line, the limitation of the pulse rate by the fixed external cavity length is removed and makes the scheme more flexible. The output with sidemode suppression ratio of more than 20 dB has been obtained. With three fiber Bragg gratings on the FBGA, we demonstrate the encoded chip rate of 1.425 GHz under the driving radio frequency of 475 MHz. It is proved that a different codeword can be generated by simply reconfiguring the encoder without changing the rest of the experimental setup.
A hierarchical network storage architecture for video-on-demand services
(1997-06-01)
Lai, YC
;
Lin, YD
;
Lai, HZ
;
交大名義發表
;
資訊工程學系
Recent advances in Cable TV networks and multimedia technologies open the possibilities for network/service/content providers to offer residential customers with video-on-demand services. However, the mass storage system in supporting such services demands proper organization and management. In this paper we present a three-level hierarchical network storage architecture for the video-on-demand storage system. At the first-level (Local Service Center, LSC) a limited number of programs with high viewing probabilities are stored; while at the second-level (Local Central Service Center, LCSC) a few programs with second high viewing probabilities are stored. The third-level (Central Service Center, CSC) contains all programs provided in the system. Based on this architecture and the program viewing probability distribution function, we use a minimum-cost function to find out the numbers of programs stored in the two service centers (LSC and LCSC) and numbers of links among these three service centers. We also describe two program reallocation algorithms which swap programs between service centers according To the change in user request patterns.
A hierarchical network storage architecture for video-on-demand services
(1996)
Lin, YD
;
Lai, HZ
;
Lai, YC
;
資訊工程學系
;
Department of Computer Science
A parallel automaton string matching with pre-hashing and root-indexing techniques for content filtering coprocessor
(2005)
Tseng, KK
;
Lin, YD
;
Lee, TH
;
Lai, YC
;
交大名義發表
We propose a new Parallel Automaton string matching approach and its hardware architecture for content filtering coprocessor. This new approach can improve the average matching time of the Parallel Automaton with Pre-Hashing and Root-Indexing techniques. The Pre-Hashing technique uses a hashing function to verify quickly the text against the partial patterns in the Automaton, and the Root-Indexing technique matches multiple bytes for the root state in one single matching. A popular Automaton algorithm, Aho-Corasick (AC) is chosen to be implemented by adding the two techniques; we employ these two techniques in a memory efficient version of AC namely Bilmap AC For the average-case time, our approach improves Bitmap AC by 494% and 224% speedup for URL and Virus patterns, respectively. Since Pre-Hashing and Root-Indexing techniques can be concurrently executed with Bitmap AC in the hardware, our proposed approach has the same worst-case time as Bitmap AC.
A simple dispersion measurement of fiber gratings by interferometric technique
(2006-01-01)
Sheu, LG
;
Chen, JM
;
Yu, SY
;
Hsu, KC
;
Tsai, MC
A simple dispersion measurement of fiber gratings using an un-balanced Michelson interferometer is proposed. A broadband source and an optical spectrum analyzer are used to scan the interference spectrum, and then the group time delay can be obtained rapidly by Fourier transform processing the interference spectrum. We measured the group time delays of a uniform-period FBG, a chirped FBG, an arrayed-waveguide grating interleaver, and a thin-film filter type OADM by an un-balanced Michelson and Mach-Zehnder interferometers, respectively. The experimental results excellent match the measured results of the optical network analyzer. The experimental repeatability is shown to be better than 1ps.
An untraceable blind signature scheme
(2003-07-01)
Hwang, MS
;
Lee, CC
;
Lai, YC
;
資訊工程學系
;
Department of Computer Science
In this paper, the authors intend to propose a new untraceable blind signature scheme based on the RSA cryptosystem. This paper applies the Extended Euclidean algorithm to our blind signature scheme. Compared with other blind signature schemes, our proposed scheme can meet the all requirements of a blind signature scheme. The security of the proposed scheme, as did that of the RSA cryptosystem, depends on the difficulty of solving the factoring problem.
Apodised fiber Bragg gratings fabricated with a uniform phase mask using Gaussian beam laser
(2000-07-01)
Yang, CC
;
Lai, YC
;
光電工程學系
;
Department of Photonics
A new exposure scheme for fabricating apodised fiber Bragg gratings by the use of a uniform phase mask and a Gaussian beam laser is demonstrated. Average refractive index is kept nearly constant along the grating to derive a side lobe suppression of 20 dB in the shorter wavelength. This scheme allows the writing of truly apodized fiber Bragg gratings. (C) 2000 Elsevier Science Ltd. All rights reserved.
Apodised fibre Bragg gratings fabricated with uniform phase mask using low cost apparatus
(2000-03-30)
Yang, CC
;
Lai, YC
;
光電工程學系
;
Department of Photonics
New exposure schemes for fabricating apodised fibre Bragg gratings using a uniform phase mask are described. A sidelobe suppression level as high as 20dB in the lower wavelength region has been successfully achieved. The schemes allow the writing of truly apodised fibre Bragg gratings using low cost and simple apparatus.
Characterization and control of highly correlated traffic in high speed networks
(1996)
Lin, YD
;
Huang, TR
;
Lai, YC
;
資訊工程學系
;
Department of Computer Science
Choice of high and low thresholds in the rate-based flow control scheme
(1999-04-01)
Lai, YC
;
Lin, YD
;
資訊工程學系
;
Department of Computer Science
In a rate-based flow control scheme, the important issue is how to determine congestion occurrence and congestion relief The most common method is to set two thresholds of queue length, a high threshold and a low threshold. The values of these two thresholds seriously influence the system performance. Hence the authors present the concept of 'best area' to determine how to set the high and low thresholds to guarantee good performance (i.e. cell loss probability is zero and utilisation is one, if it is possible). Some rules are also given to prevent unnecessary cell loss and under-utilisation, when good performance is not achieved due to too many connections or too large a propagation delay.
Complex fiber grating structures fabricated by sequential writing with polarization control
(2004-02-15)
Chu, KP
;
Lai, YC
;
Sheu, LG
;
光電工程學系
;
Department of Photonics
We propose a flexible method for fabricating complex fiber grating structures based on sequential writing for fiber gratings with polarization control of the UV source beam. Pure apodized as well as arbitrary phase-shifted fiber Bragg gratings (FBGs) can be fabricated in a single scan. Experimental examples of raised-cos(2) apodized and dispersionless FBG filters are given to demonstrate the feasibility of this method. (C) 2004 Optical Society of America.
Design and fabrication of fiberlenses for optical recording applications
(2002-03-01)
Tien, CH
;
Lai, YC
;
Milster, TD
;
Shieh, HPD
;
光電工程學系
The novel design and fabrication of a microlens on the front end of a single-mode fiber is described. The beam quality and spot size for optical recording applications are analyzed. A hyperbolic-shaped microlens on a single-mode fiber with focused spot of 1/e(2) = 0.82 mum (x-direction) and 0.89 mum (y-direction) at similar to 145 mum working distance was achieved by a simple fabrication procedure.
Direct generation of a 10 GHz 816 fs pulse train from an erbium-fiber soliton laser with asynchronous phase modulation
(2005-09-15)
Hsiang, WW
;
Lin, CY
;
Tien, MF
;
Lai, YC
;
光電工程學系
By employing the technique of asynchronous mode locking, we have successfully demonstrated direct generation of stable 10 GHz 816 fs pulse trains with a supermode-suppression ratio > 70 dB from a hybrid mode-locked Er-fiber laser. When the modulation frequency deviates from the cavity harmonic frequency by 15-40 kHz, stable femtosecond soliton pulses are formed. Our results demonstrate that asynchronous mode locking can act as an effective mechanism for achieving a shorter pulse width and for stabilizing high-repetition-rate pulse trains in soliton fiber lasers. (c) 2005 Optical Society of America.
Evaluation of immunomagnetic separation method for detection of Giardia for different reaction times and reaction volumes
(2001-06-01)
Hsu, BM
;
Huang, CP
;
Lai, YC
;
Tai, HS
;
Chung, YC
Immunomagnetic separation (IMS) has been specified as a standard method for the measurement of Giardia. In this study, Dynal IMS was evaluated on the basis of recovery efficiencies of Giardia cysts for various IMS operational conditions. The average recoveries for Giardia in deionized, treated and raw water samples were 82.6 +/- 12.2% (n = 6), 75.6 +/- 15.2% (n=3), and 70.6 +/- 18.2% (n = 3), respectively. Significant changes in recovery were observed by altering the debris ratio and the debris components of water samples. Changing the reaction volume within the same vessel had no significant effect on cyst recovery efficiencies. However, prolonging the reaction time did increase recovery efficiencies.
Fiber bragg grating dispersion compensator by single-period overlap-step-scan exposure
(2003-07-01)
Sheu, LG
;
Chuang, KP
;
Lai, YC
;
光電工程學系
;
Department of Photonics
We theoretically demonstrate that a high-quality fiber Bragg grating dispersion compensator can be fabricated by a properly designed single-period overlap-step-scan exposure method. A practical design example and a detailed tolerance analysis of this new fabrication method are given.
Fiber Bragg grating sequential UV-writing method with real-time interferometric side-diffraction position monitoring
(2005-05-16)
Hsu, KC
;
Sheu, LG
;
Chuang, KP
;
Chang, SH
;
Lai, YC
This work presents a new sequential UV-writing procedure for fabricating long fiber Bragg grating (FBG) devices. To real-time accurately align the position of every exposed FBG section prior to UV exposure, a single-period reference fiber grating with strong refractive index modulation is probed by applying an interferometric side-diffraction method to measure the grating phase as the position reference. In this way the overlapped FBG sections can be connected section-by-section without obvious phase errors, even when the written index-modulation is weak. (C) 2005 Optical Society of America.
Fiber-lens-based module for optical recording applications
(2003-07-01)
Tien, CH
;
Chou, HL
;
Chiu, Y
;
Hsu, W
;
Milster, TD
An optical fiber-lens-type pickup with numerical aperture (NA) congruent to 0.27 was demonstrated for thermal recording of continuous 1.6-mum-wide lines on MO disks with 50% throughput efficiency. Moreover, a Si-micromachined near-field module integrated with a fiber lens, solid immersion lens (SIL), and submicron aperture was fabricated to improve the mechanical fragility and increase the NA of the optical-fiber-based pickup. The preliminary configuration design and measurement suggest the feasibility of the module as a submicron heat source for high-density optical data storage.
Fluorescence squeezing spectra near a photonic bandgap
(2004-08-01)
Lee, RK
;
Lai, YC
;
光電工程學系
;
Department of Photonics
The fluorescence intensity and quadrature spectra from a two-level atom embedded in a photonic bandgap crystal and resonantly driven by a classical pump light are calculated. The non-Markovian nature of the problem caused by the non-uniform distribution of the photonic density of states is handled by linearizing the generalized optical Bloch equations with the Liouville operator expansion. Unlike the case in free space, we find that the bandgap effects will not only modify the fluorescence spectral shape but also cause squeezing in the in-phase quadrature spectra.
GMNF-DVMRP: A modified version of Distance Vector Multicast Routing Protocol
(1997)
Lai, YC
;
Lin, YD
;
Yu, WC
;
Lin, YT
;
交大名義發表
In this paper, we make a survey of Distance Vector Multicast Routing Protocol (DVMRP) and find that it is not optimal in the aspect of network cost (NC). Therefore, we propose a modified version of DVMRP, called ''Group Membership Near First-DVMRP'' (GMNF-DVMRP), to decrease the NC of the multicast tree formed by DVMRP. A simulation is implemented to compare our modified version and the original DVMRP. We find that our method save about 5-7 percent of NC of the multicast tree formed by DVMRP.