Browsing by Author "Lu, YH"

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All-optical gain-clamped wideband serial EDFA with ring-shaped laser
(2004-01-02)
Lu, YH
;
Chi, S
;
光電工程學系
;
Department of Photonics
We experimentally investigate the static and dynamic properties of all-optical gain-clamped wideband (1530-1600 nm) serial erbium-doped fiber amplifier with a single ring-shaped laser, which consists of a circulator and a fiber Bragg grating at the output end. The lasing light passing through the second stage is intentionally blocked at the output end by a C/L-band wavelength division multiplexer owning the huge insertion loss, and thus, the copropagating ring-laser light is formed by the first stage. This design can simultaneously clamp the gains of 1547 and 1584 nm probes near 14 dB and shows the same dynamic range of input power up to -4 dBm for conventional band and long-wavelength band. Furthermore, the transient responses of 1551 and 1596 nm surviving channels exhibit small power excursions (<0.54 dB) as the total saturating tone with -2 dBm is modulated on and off at 270 Hz. (C) 2003 Elsevier B.V. All rights reserved.
Mask films for thermally induced superresolution readout in rewritable phase-change optical disks
(2001-03-01)
Lu, YH
;
Dimitrov, D
;
Liu, JR
;
Hsieh, TE
;
Shieh, HPD
Tellurium was studied as a mask film in a thermally induced superresolution rewritable optical disk for detecting below-diffraction-limit marks. Mark trains of 0.15 mum could be retrieved with 9 dB in carrier-to-noise (CNR) using an optical system with the laser wavelength of 780 nm and an objective lens of 0.55 numerical aperture. Readout cyclability was examined and methods to further improve readout cyclability were proposed.
Oxygen and nitrogen co-doped GeSbTe thin films for phase-change optical recording
(2002-03-01)
Dimitrov, DZ
;
Lu, YH
;
Tseng, MR
;
Hsu, WC
;
Shieh, HPD
Nitrogen and oxygen co-doped GeSbTe films for phase-change optical recording are investigated. It is found that optical properties of amorphous and crystalline state are similar to that of GeSbTe, crystallization temperature increases and crystalline microstructure is refined which indicate a nucleation rate increases by co-doping. The carrier-to-noise ratio (CNR) and erasability of phase-change optical disks are improved being up to 52 dB and 35 dB, respectively, by using an appropriate co-doping concentration in the recording layer.
Preparation of poly(2,5-thienyleneethylene) and poly(2,5-furyleneethylene) by vapor phase pyrolysis of (5-methyl-2-thienyl)methyl benzoate and (5-methyl-2-furyl)methyl benzoate
(1996-08-12)
Lu, YH
;
Hsu, CS
;
Chou, CH
;
Chou, TH
;
應用化學系
The synthesis-of poly(2,5-thienyleneethylene) and poly(2,5-furyleneethylene) by vapor deposition polymerization is presented. (5-Methyl-2-thienyl)methyl benzoate and (5-methyl-2-furyl)methyl benzoate were subjected to vapor phase pyrolysis above 650 degrees C to form 2,5-dimethylene-2,5-dihydrothiophene and 2,5-dimethylene-2,5-dihydrofuran. Upon condensation, both compounds spontaneously polymerize, respectively, at a temperature higher than -25 degrees C to produce poly(2,5-thienyleneethylene) and poly(2,5-furyleneethylene). The obtained poly(2,5-thienyleneethylene) is soluble in chloroform above 60 degrees C. It is a semicrystalline polymer and displays a glass transition at around 25 degrees C and a melting transition at around 160 degrees C. The synthesized poly(2,5-furyleneethylene) is insoluble in tetrahydrofuran, chloroform, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) at room temperature and only swells in DMF and DMOS above 100 degrees C. Solid-state NMR studies show that the poly(2,5-furyleneethylene) is cross-linked. The poly(2,5-furyleneethylene) is also a semicrystalline polymer exhibiting a glass transition at around 20 degrees C and a melting transition at around 110 degrees C. Solution polymerizations of 2,5-dimethylene-2,5-dihydrothiophene and 2,5-dimethylene-2,5-dihydrofuran were also carried out, respectively, in THF to yield poly(2,5-thienyleneethylene) and poly(2,5-furyleneethylene). Finally, the relative merits for the polymerization of 2,5-dimethylene-2,5-dihydrothiophene and 2,5-dimethylene-2,5-dihydrofuran by both methods are compared.
Synthesis and characterization of side-chain liquid crystalline polyoxetanes containing 4-(alkanyloxy)phenyl 4-pentylbenzoate side groups
(1999-07-01)
Hsu, CS
;
Lu, YH
;
應用化學系
;
Department of Applied Chemistry
The synthesis and characterization of side-chain liquid-crystalline polyoxetanes containing 4-(alkanyloxy)phenyl 4-pentylbenzoate side groups is presented. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction measurements were used to characterize the mesomorphic properties of the polyoxetanes. Those polymers with three to five methylene units in the spacers exhibit the enantiotropic smectic A and a nematic phaser, whereas the polymers with longer spacers (n = 6 or 12) display polymorphism of smectic phases. The polyoxetane backbones are amorphous in nature. No side chain crystallization occurred for any of the polyoxetanes synthesized in this study.
Two-stage L-band EDFA applying C/L-Band wavelength-division multiplexer with the counterpropagating partial gain-clamping
(2003-12-01)
Lu, YH
;
Chi, SE
;
光電工程學系
;
Department of Photonics
A simple ring laser technique of two-stage gain-clamped long-wavelength band erbium-doped fiber amplifier is investigated. The ring laser light is excluded at the output end and noise-figure degradation can. be reduced due to the counterpropagating partial gain-clamping in the second stage. The laser mechanism is achieved by the C/L-band wavelength-division multiplexer instead of a tunable bandpass filter and an optical circulator at the output end, which,were often used in the previous counterpropagating ring laser architectures, and thus, this design is cost-effective. The gain-clamping of long-wavelength band (1569-1606.2 nm) in our configuration is demonstrated experimentally for the saturating tone (1587.6 nm) power up to -2 dBm.