Browsing by Author "Yang, PK"

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A real-time poling approach for preparing second-order nonlinear optical polymer thin films
(1997-07-30)
Jou, JH
;
Wu, HS
;
Chiou, JF
;
Yang, PK
;
Huang, JY
A new real-time poling approach for preparing second-order nonlinear optical (NLO) polymer thin films is presented. The presented method may be conveniently applied to many polymer thin film systems without going through the complicated conventional synthesis and poling procedures. This method, which is proven in this work to be feasible experimentally, is done by simultaneously co-depositing a NLO active dye, disperse red 1 and two polyamide thin film forming monomers on a gold electrodes pre-patterned glass substrate while concurrently applying an electrical field for poling. A second harmonic generation (SHG) signal is detected from the resultant thin films at a very low poring field ranging from 0.01 to 0.1 MV/cm which increases in intensity as the poling field increases. (C) 1997 Elsevier Science S.A.
A real-time poling approach for preparing second-order nonlinear optical polymer thin films
(1997-07-30)
Jou, JH
;
Wu, HS
;
Chiou, JF
;
Yang, PK
;
Huang, JY
A new real-time poling approach for preparing second-order nonlinear optical (NLO) polymer thin films is presented. The presented method may be conveniently applied to many polymer thin film systems without going through the complicated conventional synthesis and poling procedures. This method, which is proven in this work to be feasible experimentally, is done by simultaneously co-depositing a NLO active dye, disperse red 1 and two polyamide thin film forming monomers on a gold electrodes pre-patterned glass substrate while concurrently applying an electrical field for poling. A second harmonic generation (SHG) signal is detected from the resultant thin films at a very low poring field ranging from 0.01 to 0.1 MV/cm which increases in intensity as the poling field increases. (C) 1997 Elsevier Science S.A.
An inexpensive diode-pumped mode-locked Nd : YVO4 laser for nonlinear optical microscopy
(2000-01-01)
Yang, PK
;
Huang, JY
;
光電工程學系
;
Department of Photonics
We report an inexpensive diode-pumped Nd:YVO4 laser mode-locked with combined effects of nonlinear mirror (NLM) and cascaded second-order optical nonlinearities (CSON) in a KTP crystal. Detailed analysis, which takes into account the transverse effect of cavity modes, shows that the CSON effect dominates the mode locking process. The resulting self-defocusing lens couples with an aperture appearing in the gain medium and then produces a cavity loss modulation. The mode locking self starts at a pump power of 2.2 W with a 35% transmission output coupler and generates pulses with a duration of 14 ps and an averaged power of 350 mW. The laser was shown to be useful for probing polar structures of nonlinear optical materials with second harmonic microscopy. (C) 2000 Elsevier Science B.V. All rights reserved.
Linewidth-deduction method for nonlinear optical spectroscopy with transform-limited light pulses
(1998-03-01)
Yang, PK
;
Huang, JY
;
光電工程學系
;
Department of Photonics
We have developed a Fourier-deconvolution-based linewidth-deduction method for nonlinear optical spectroscopy with transform-limited light pulses. The phase-retrieval problem involved in this method was solved with a phase-retrieval procedure based on the maximum-entropy model. Our proposed method can also help one to surpass the resolution limit set by the uncertainty principle when the amplitude line-shape function of the laser source can be fully predetermined. (C) 1998 Optical Society of America [S0740-3224(98)00303-8].
Model-independent maximum-entropy method for the analysis of sum-frequency vibrational spectroscopy
(2000-07-01)
Yang, PK
;
Huang, JY
;
光電工程學系
;
Department of Photonics
We have developed and applied a maximum-entropy phase-retrieval procedure to analyze sum-frequency vibrational spectra from a CCl4/octadecyl tricholosilane/silica interface and a hydrogen-terminated diamond C(111) surface. Some a priori knowledge of a nonlinear optical spectrum was employed for determining the phase of nonlinear optical susceptibility, and therefore the requirement for experimental phase measurement can be avoided. The results agree well with those from the Lorentzian line-shape model and justify the applicability of the a priori constraints employed in our phase-retrieval procedure. (C) 2000 Optical Society of America [S0740-3224(00)00907-3].
Molecular conformation and nanomechanics of self-assembled alkylsiloxane monolayers
(1997-01-08)
Huang, JY
;
Song, KJ
;
Lagoutchev, A
;
Yang, PK
;
Chuang, TJ
We have studied the chain conformation and nanomechanical properties of pure alkylsiloxane monolayers and the mixed films with fluorine-containing species using scanning force microscopy (SFM) and infrared-visible sum-frequency generation spectroscopy (IV-SFG). Our IV-SFG spectra yield information about the chain ordering and surface density of specific species in the pure and mixed monolayers. A film formation process involving preferential adsorption of the fluorinated species from solution was observed. On the basis of the SFM measurements, the stiffness of alkylsiloxane monolayers under load was found to increase with the chain length, changes of chain conformation, and alkyl chain fluorination.
Molecular conformation and nanomechanics of self-assembled alkylsiloxane monolayers
(1997-01-08)
Huang, JY
;
Song, KJ
;
Lagoutchev, A
;
Yang, PK
;
Chuang, TJ
We have studied the chain conformation and nanomechanical properties of pure alkylsiloxane monolayers and the mixed films with fluorine-containing species using scanning force microscopy (SFM) and infrared-visible sum-frequency generation spectroscopy (IV-SFG). Our IV-SFG spectra yield information about the chain ordering and surface density of specific species in the pure and mixed monolayers. A film formation process involving preferential adsorption of the fluorinated species from solution was observed. On the basis of the SFM measurements, the stiffness of alkylsiloxane monolayers under load was found to increase with the chain length, changes of chain conformation, and alkyl chain fluorination.
Phase-retrieval problems in infrared-visible sum-frequency generation spectroscopy by the maximum-entropy method
(1997-10-01)
Yang, PK
;
Huang, JY
;
光電工程研究所
;
Institute of EO Enginerring
A phase-retrieval procedure based on the maximum-entropy method is applied to infrared-visible sum-frequency generation spectroscopy. Several typical effects on the error phase are also examined with the aid of a known theoretical model. The interference between the resonant and the nonresonant parts changes the behavior of the error phase. Even in some cases when the nonresonant part is complex, the error phase becomes like a step function. This result contradicts the smoothness assumption for the error phase, and the whole phase-retrieval procedure breaks down in these cases. A comparison of the results of phase-retrieval procedures between infrared-visible sum-frequency generation and coherent anti-Stokes Raman scattering spectra is made. Some ideas that worked well in previous analyses of coherent anti-Stokes Raman scattering spectra become inapplicable in the infrared-visible sum-frequency generation spectra in spite of the resemblance of their line shape functions. (C) 1997 Optical Society of America.
Phase-retrieval problems in infrared-visible sum-frequency generation spectroscopy by the maximum-entropy method
(1997-10-01)
Yang, PK
;
Huang, JY
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
A phase-retrieval procedure based on the maximum-entropy method is applied to infrared-visible sum-frequency generation spectroscopy. Several typical effects on the error phase are also examined with the aid of a known theoretical model. The interference between the resonant and the nonresonant parts changes the behavior of the error phase. Even in some cases when the nonresonant part is complex, the error phase becomes like a step function. This result contradicts the smoothness assumption for the error phase, and the whole phase-retrieval procedure breaks down in these cases. A comparison of the results of phase-retrieval procedures between infrared-visible sum-frequency generation and coherent anti-Stokes Raman scattering spectra is made. Some ideas that worked well in previous analyses of coherent anti-Stokes Raman scattering spectra become inapplicable in the infrared-visible sum-frequency generation spectra in spite of the resemblance of their line shape functions. (C) 1997 Optical Society of America.
Second-order nonlinearities and crystal structures of methylsulfonyl- and phenylsulfonyl-substituted thiophene imino dyes
(1996-05-07)
Chou, SSP
;
Sun, DJ
;
Lin, HC
;
Yang, PK
;
光電工程研究所
A simple synthesis of sulfone-substituted thiophene imino dyes 5 and 6 and their UV-VIS absorptions, second-order nonlinear optical properties, X-ray crystal structures and thermal stabilities are described.
Second-order nonlinearities and crystal structures of methylsulfonyl- and phenylsulfonyl-substituted thiophene imino dyes
(1996-05-07)
Chou, SSP
;
Sun, DJ
;
Lin, HC
;
Yang, PK
;
光電工程學系
A simple synthesis of sulfone-substituted thiophene imino dyes 5 and 6 and their UV-VIS absorptions, second-order nonlinear optical properties, X-ray crystal structures and thermal stabilities are described.
Self-assembly of alkylsiloxane monolayers on fused silica studied by XPS and sum frequency generation spectroscopy
(1998-01-15)
Lagutchev, AS
;
Song, KJ
;
Huang, JY
;
Yang, PK
;
Chuang, TJ
Infrared-visible sum frequency generation (SFG) vibrational spectroscopy in the C-H stretching region was used to study a set of self-assembled monolayers, formed from octyltrichlorosilane [CH3(CH2)(7)SiCl3], its partially fluorinated analog, (tridecafluoro-1,1,2,2-tetrahydrooctyl)-1-trichlorosilane [CF3-(CF2)(5)(CH2)(2)SiCl3] and their mixtures. SFG measurements were complemented with transmission-absorption FTIR spectroscopy and X-ray photoemission spectroscopy. Simultaneous self-assembly of both chlorosilanes results in preferential deposition of the fluorinated compound. The major reason for this behavior is the alkyl chain fluorination. There is a strong spectroscopic evidence of close coadsorption of fluorinated and non-fluorinated molecules in mixed monolayers. It follows that the species in self-assembled monolayers of binary composition do not segregate into different phases as it is observed for similar Langmuir-Blodgett films. Distinct differences found in SFG spectra of fluorinated and non-fluorinated samples indicate that SFG spectroscopy is much more sensitive than FTIR in detection of symmetry distortions in the alkyl chain of the amphiphiles. Both SFG and FTIR spectroscopic data show the presence of hydrocarbon residue in fluorinated and mixed films that is very likely due to hexadecane used as a solvent during monolayer deposition. (C) 1998 Elsevier Science B.V.
Sum-frequency generation from an isotropic chiral medium
(1998-06-01)
Yang, PK
;
Huang, JY
;
光電工程學系
;
Department of Photonics
We report a theoretical analysis of nonlinear optical sum-frequency generation from the bulk of a chiral liquid in the dipole approximation. In our theoretical formulation the circular birefringence effect of a chiral medium was properly taken into account. The angular dependence of the reflected and transmitted sum-frequency signals on the incident angles of two input beams was calculated to yield the optimal geometry for probing bulk chirality. We also derived a microscopic expression for the totally antisymmetric part of a second-order nonlinear optical susceptibility to elaborate unique features in the studies of chirality-related properties with sum-frequency generation. (C) 1998 Optical Society of America.
Sum-frequency vibrational spectroscopic study of mixed alkylsiloxane monolayers self-assembled on fused silica surface
(1997-10-01)
Lagutchev, AS
;
Song, KJ
;
Huang, JY
;
Yang, PK
;
Chuang, TJ
Self-assembled monolayers of fluorinated and non-fluorinated alkylsiloxanes were prepared on fused silica substrates and studied by both conventional IR and nonlinear sum-frequency vibrational spectroscopy complemented with XPS. Simultaneous self-assembly of the two alkylsiloxanes results in preferential adsorption of the fluorinated compound and formation of the mixed monolayer. Different species are found to be closely coadsorbed in the mixed monolayers which distinguishes self-assembly from Langmuir-Blodgett deposition where the similar species tend to separate into different phases. Nonlinear sum-frequency spectroscopy of C-H stretching region detects symmetry perturbations of the alkyl chain induced by trans-cis defects and partial fluorination and clearly distinguishes between them. All three characterization methods consistently indicate the presence of a hydrocarbon residue in all deposited monolayers, which is ascribed to the hexadecane used as a solvent during the self-assembly process. (C) 1997 Elsevier Science S.A.
Synthesis and second-order nonlinearities of chiral prolinol-substituted chromophores
(2004-06-01)
Chou, SSP
;
Yu, CY
;
Lin, HC
;
Yang, PK
;
光電工程學系
A new series of thiophene- and furan-containing chromophores with a chiral prolinol donor and a sulfone acceptor has been synthesized. The UV-vis absorptions, second-order nonlinear optical properties, and X-ray crystal structures are described.
Synthesis of sulfone-substituted thiophene chromophores for second-order nonlinear optics
(1996-09-30)
Chou, SSP
;
Sun, DJ
;
Huang, JY
;
Yang, PK
;
Lin, HC
A new series of conjugated thiophene compounds 1-4 containing methylsulfonyl and phenylsulfonyl accepters have been synthesized which possess efficient second-order optical nonlinearities, high thermal stability and good transparency for use as nonlinear optical materials. Copyright (C) 1996 Elsevier Science Ltd