Browsing by Author "Lee, CC"

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120-nm bandwidth erbium-doped fiber amplifier in parallel configuration
(2004-07-01)
Yeh, CH
;
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
A new S- to L-band erbium-doped fiber amplifier (EDFA) module, which reaches 120-nm gain bandwidth of 1480 to 1600 nm, has been experimentally investigated and demonstrated by using coupled structure. A 32.8-, 34.7-, and 38.1-dB peak gain is obtained at 1504, 1532, and 1568 nm, respectively, when the input signal power is -30 dBm. In addition, this proposed amplifier also provides a broad-band amplified spontaneous emission (ASE) light source of 1480-1606 nm with the output level above -40 dBm.
A bidirectional 2 x 2 optical switch technique using absorption or amplification function of erbium-doped fiber
(2005-10-01)
Yeh, CH
;
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
A novel bidirectional 2 x 2 optical switch technique, based on conventional erbium-doped fibers (EDFs) that operate at a pumped or unpumped power level, is proposed and demonstrated experimentally. By using the amplification and absorption functions of EDFs and a simple architecture design, the input signals can be switched to a suitable port. The response time of wavelength switching approaches about 2 ms. Moreover, the behavior and system performance of the proposed configuration are also studied.
A new key authentication scheme based on discrete logarithms
(2003-07-15)
Lee, CC
;
Hwang, MS
;
Li, LH
;
資訊工程學系
;
Department of Computer Science
In this article, we propose a new public key authentication scheme for cryptosystems with a trusty server. The scheme is based on discrete logarithms. In the scheme, the certificate of the public key is a combination of user's password and private key. The scheme not only resolve the problems appeared but also is secure for the others public-key authentication. (C) 2002 Elsevier Science Inc. All rights reserved.
A new privacy and authentication protocol for end-to-end mobile users
(2003-11-01)
Lee, CC
;
Yang, CC
;
Hwang, MS
;
資訊工程學系
;
Department of Computer Science
In this papecr. we propose a new privacy and authentication scheme for end-to-end mobile users. There are three goals in our scheme. The first allows two end-to-end mobile users to communicate privately each other. The second allows two end-to-end mobile users to distribute a session key simply. The third allows two end-to-end mobile users to mutually authenticate. Copyright (C) 2003 John Wiley Sons, Ltd.
A novel register organization for VLIW digital signal processors
(2005)
Lin, TJ
;
Lee, CC
;
Liu, CW
;
Jen, CW
;
電子工程學系及電子研究所
This paper presents a novel register organization for VLIW DSPs. The simulation results show the performance of a DSP with the proposed register file is comparable with state-of-the-art DSPs. However, the proposed register file can save 89.7% area of a conventional centralized one, while reducing its access time by 68.6%.
A novel supervisory scheme for OXC based on different time-dilay recognition
(2005-12-01)
Lee, CC
;
Kao, TC
;
Chien, HC
;
Chi, S
;
光電工程學系
A novel supervising technique, based on different time-delay recognition scheme, for monitoring the switch fabric of optical cross-connects is proposed. This method features fast detection, high reliability, fault location, and actual routing information. The supervising of 4 x 4 switch fabric with a detecting time of less than 300 ns was achieved. It is also verified experimentally that the degradation of the system performance caused by this supervising approach is negligible.
A practical in-service supervisory technique using reflected-pulse detection based on OTDR for optically amplified passive branched CATV networks
(1999-05-01)
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
We propose and experimentally demonstrate an inservice supervisory tecchnique based on reflected-pulse detection, which can simultaneously monitor the performance of all active network devices (such as optical transmitter, optical amplifiers, and optical receivers) and locate the fiber fault in optically amplified passive branched cable TV networks by using a conventional optical time-domain reflectometer (OTDR) combined with 1 x 2 optical switches. The monitoring parameters such as required dynamic range of OTDR, response time, and the maximum number of element monitoring transponder are discussed.
A simple and low-cost method to fabricate TFTs with poly-Si nanowire channel
(2005-09-01)
Lin, HC
;
Lee, MH
;
Su, CJ
;
Huang, TY
;
Lee, CC
A very simple and low-cost scheme is proposed for fabricating thin-film transistors with poly-Si nanowire (NW) channels. In this scheme, the poly-Si NW channel is formed by cleverly employing the poly-Si sidewall spacer technique. In addition, the poly-Si NW channel is genuinely exposed to the environment after the poly-Si sidewall spacer formation in the new scheme. This unique feature, together with its simplicity and low-cost, makes this approach very suitable for applications and manufacturing of bio-logic sensing devices. Good device performance is demonstrated in this letter.
A simple remote user authentication scheme
(2002-07-01)
Hwang, MS
;
Lee, CC
;
Tang, YL
;
資訊工程學系
;
Department of Computer Science
In this article, we propose a simple remote user authentication scheme using smart cards. This scheme has the following features. First, it does not require any password or verification tables. Second, it can withstand the message replay attack. Third, any legal users can arbitrarily choose and change their own passwords at will. And finally, the password of a user is not revealed to the server. In addition, the computational costs of this scheme are less than those of any previously proposed schemes. (C) 2002 Elsevier Science Ltd. All rights reserved.
A stabilized and tunable erbium-doped fiber ring laser with double optical filter
(2004-03-01)
Yeh, CH
;
Lee, CC
;
Chen, CY
;
Chi, S
;
光電工程學系
We have proposed and experimentally demonstrated a stabilized and tunable erbium-doped fiber ring laser by using a Fabry-Perot laser and a fiber Fabry-Wrot filter. The sidemode suppression ratio of >30 dB/0.1 nm and the output power of >2.2 dBm can be achieved while this ring laser is tuned from 1528.28 to 1559.64 nm with the step of 1.12 nm. The wavelength variation of less than 0.01 nm and the power fluctuation of less than or equal to0.04 dB have also been obtained. When the constant output power is controlled by adjusting the bias current of 980-nm pump laser, the power variation of less than +/-0.05 dB can be obtained over the entire tunable range.
A tunable and single-frequency S-band erbium fiber laser with saturable-absorber-based autotracking filter
(2005-06-01)
Chien, HC
;
Yeh, CH
;
Lee, CC
;
Chi, S
;
光電工程學系
A method to achieve wavelength tunability and single-longitudinal-mode oscillation in an S-band erbium-doped fiber (EDF) ring laser is proposed and demonstrated. A saturable-absorber-based autotracking filter consisting of an unpumped EDF and an optical reflector is utilized to provide fine mode restriction and guarantee the single-frequency operation. The performance of output power of larger than 1 dBm, power stability of smaller than 0.02 dB, wavelength variation of less than 0.01 nm and side-mode suppression ratio of larger than 31 dB has been experimentally demonstrated for this single-frequency fiber laser operating from 1482 to 1512 nm. (C) 2005 Elsevier B.V. All rights reserved.
A tunable C-plus-L-band fiber ring laser based on hybrid amplifier
(2004-02-01)
Yeh, CH
;
Lee, CC
;
Chen, CY
;
Chi, S
;
光電工程學系
A tunable C-plus-L-band fiber ring laser, based on a semiconductor optical amplifier, which directly connects an erbium-doped fiber amplifier with a 16 m long erbium-doped fiber, has been proposed and experimentally investigated. A side-mode suppression ratio of > 40 dB/0.1 nm and an output power of >3 dBm in the operating range from 1552 to 1610 nm have been achieved for this ring laser.
A tunable S-band erbium-doped fiber ring laser
(2003-08-01)
Yeh, CH
;
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
In this paper, we experimentally investigate and demonstrate an S-band erbium-doped fiber (EDF) ring laser based on an erbium-doped silica fiber and 980-nm pumping laser. Widely tunable range from 1480 to 1522 run, and the sidemode suppression ratio (SMSR) of >30 dB/0.1 nm and the output power of > -2 dBm in the operating range from 1482 nm to 1517 nm have been achieved for this ring laser. Under the constant power control, the output power variation less than +/-0.05 dB can also be accomplished over the tuning range from 1482 to 1517 run. This S-band EDF ring laser is promising for the future S-band applications.
All optical cross-connect system using erbium-doped fiber-based optical switching unit
(2006-01-01)
Yeh, CH
;
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
A novel bidirectional 2x2 optical switch technique, based on the conventional erbium-doped fibers (EDFs) with an operation of pumped or unpumped power level, is proposed and demonstrated experimentally, By using the amplification and absorption function of EDFs and a simply architecture design, the input signals can be switched to a suitable position. The response time of wavelength switching will approach about 2 ms. Moreover, the behavior and system performance of the proposed configuration also have been studied.
All-optical 2R regeneration based on a compact self-seeded Fabry-Perot laser diode with an embedded fiber Bragg grating
(2006-01-01)
Chien, HC
;
Lee, CC
;
Chen, YM
;
Feng, KM
;
Chi, S
A cost-effective method, based on the injection-locking technique of a compact self-seeded Fabry-Perot laser diode with a 10-mm-long embedded fiber Bragg grating cavity, is proposed and experimentally compared with the two-mode injection-locked scheme for all-optical 2R regeneration at 10 Gb/s. Placing the presented all-optical 2R regenerator after a 50-km fiber significantly improves the transmission performance of a signal over 50- and 100-km fiber links. The power penalties at BER = 10(-9) are similar to those of the two-mode injection-locked scheme.
An all-optical 2R regenerator using a compact self-seeded Fabry-Perot laser diode incorporated in a bidirectional EDFA
(2006-05-01)
Chien, HC
;
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
An all-optical 2R regenerator, based on a compact self-seeded Fabry-Perot laser diode with a 10-mm-long embedded fiber Bragg grating cavity, and a bidirectional erbium-doped fiber amplifier, is proposed and experimentally demonstrated to execute all-optical 211 regeneration at 10 Gb/s. Compared with the conventional 111 regeneration, the proposed scheme has achieved significant 6.4-dB improvement of power penalty at bit-error ratio = 10(-9) in the transmission experiment over 100-km standard single-mode fiber.
An efficient VLIW DSP architecture for baseband processing
(2003)
Lin, TJ
;
Chang, CC
;
Lee, CC
;
Jen, CW
;
電子工程學系及電子研究所
The VLIW processors with static instruction scheduling and thus deterministic execution times are very suitable for high-performance real-time DSP applications. But the two major weaknesses in VLIW processors prevent the integration of more functional units (FU) for a higher instruction issuing rate - the dramatically growing complexity in the register file (RF), and the poor code density. In this paper, we propose a novel ring-structure RF, which partitions the centralized RF into 2N sub-blocks with an explicit N-by-N switch network for N FU. Each sub-block only requires access ports for a single FU We also propose the hierarchical VLIW encoding with variable-length RISC-like instructions and NOP removal. The ring-structure RF saves 91.88% silicon area and reduces 77.35% access time of the centralized RF. Our simulation. results show that the proposed instruction set architecture with the exposed ring-structure RF has comparable performance with the state-of-the-art DSP processors. Moreover, the hierarchical VLIW encoding can save 32%similar to50% code sizes.
An improvement of mobile users authentication in the integration enviromnents
(2002)
Hwang, MS
;
Lee, CC
;
Yang, WP
;
資訊工程學系
;
Department of Computer Science
This paper shows that Tzeng and Tzeng's protocol has a drawback that the protocol can be easily crashed by an evil VLR attack. Therefore, we propose a slight modification to their protocol to improve their shortcoming. As a result, our protocol does not only enhance the security of Tzeng and Tzeng's protocol but also improves the efficiency.
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.
Aqueous tape casting of microwave ceramic BaO center dot La2O3 center dot 4.7TiO(2)
(1998-12-01)
Lee, CC
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
An aqueous-based slip for tape-casting BaO . La2O3. 4.7TiO(2) ceramic sheets was studied that is suitable for substrates of microwave devices. Two separate dispersants, Na4P2O7 (S2) and CH3(CH2)(4)SO3Na, combined with poly(vinyl alcohol) and poly(ethylene glycol), were used as slip additives. The zeta potential, particle size distribution, viscosity (of the slip), tensile strength and density (of green tapes), sintered density, microstructures and microwave dielectric properties (of sintered substrates) were characterized, and their dependence on the additives were analysed. S2 shows a better dispersion function and leads to a higher density of the tapes. During the sintering, the S2 liquid on grain boundaries hindered the grain growth and the formation of second phase. The dispersant-dependent microstructures of the substrates show strong influences on the dielectric properties.