Browsing by Author "Tsai, KT"

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740-km transmission of 78-channel 64-QAM signals (2.34 Gb/s) without dispersion compensation using a recirculating loop
(2000-09-01)
Wu, MC
;
Wong, JK
;
Tsai, KT
;
Chen, YL
;
Way, WI
A long-distance 1550-nm subcarrier multiplexed lightwave trunk system that transported 78 channels of 64-QAM signals was demonstrated in a recirculating loop experiment. Each channel can achieve a carrier-to-(noise + nonlinear distortion) ratio of 30 dB after 740-km transmission through conventional single-mode fiber without dispersion compensation.
Alignment monitoring technique for pulse carver and data modulator in RZ-DPSK systems using an optical frequency discriminator
(2006-05-01)
Tsai, KT
;
Lu, GW
;
Chen, LK
;
Way, WI
;
電信工程研究所
A technique for monitoring the timing alignment between a pulse carver and a phase modulator in return-to-zero differential phase-shift keying systems is proposed. An optical frequency discriminator and a microwave detector centered at a half of the phase modulation data rate are used to monitor the spectrum broadening caused by timing misalignment., The proposed method has a large detection dynamic range and is polarization-independent.
Chromatic-dispersion monitoring using an optical delay-and-add filter
(2005-11-01)
Tsai, KT
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
A novel postdetection method based on an optical delay-and-add filter (DAF) is proposed for dispersion monitoring at 40 Gb/s or beyond. The proposed method can be used with or without a pilot tone and works well even when there exists a residual chirp due to the finite direct current (DC) extinction ratio of a Mach-Zehnder (MZ) modulator or self-phase modulation (SPM). Several modulation formats, including conventional nonreturn to zero (NRZ), return to zero (RZ), carrier-suppressed RZ (CSRZ), RZ differential phase shift keying (RZ-DPSK), and CSRZ-DPSK are used to numerically demonstrate the feasibility of this technique without using a pilot tone.
High birefringent liquid crystals
(1995)
Wu, ST
;
Margerum, JD
;
Ho, MS
;
Fung, BM
;
Hsu, CS
Several liquid crystal dyes and fluorinated compounds with high birefringence are synthesized and their properties evaluated. These polar compounds are useful dopants for enhancing the dielectric anisotropy of the dialkyl diphenyl-diacetylene host.
Novel electro-optical pre-distortion technique and its application in externally modulated CATV transmission systems
(1998)
Tsai, KT
;
Tai, C
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
Conventional linearization techniques such as electrical pre-distortion or optical feedforward methods have been applied to Mach-Zehnder interferometer (MZI) modulators for CATV transmission systems. However, both methods can only ensure that the output of the MZI modulator meet the standard CATV requirements on composite second-order (CSO) and composite triple beat (CTB), but cannot guarantee a satisfactory end-to-end system linearity. In this paper, we propose and demonstrate a novel linearization technique, which can simultaneously suppress the nonlinear distortions (NLDs) generated in a transmission system and increase the received carrier-to-noise ratio (CNR). This technique is based on offsetting the MZI bias voltage from its inflection point. Both analytical and experimental results are presented.