摘要:

The linear and third order nonlinear optical properties of a polythiophene derivative incorporating 5,6-dialkoxy-thieno[3,4-b]pyrazine units were investigated. This low band gap material has a large oscillator strength, weak photoluminescence and strong enhancement of the Raman bands. We surmise that the long conjugation length of the polymer backbone, as well as the effect of the substituents on the π-electrons, give rise to a large value of the third order nonlinear susceptibility, χ(3). Measurements by Z-scan and third harmonic generation (THG) corroborate earlier results from degenerate four wave mixing (DFWM) experiments. The χ(3)values from Z-scan with 20 ps pulses were over 10−7esu near the lowest energy absorption band.

ISSN:1058-725X    

DOI:10.1080/10587259808044313

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Two different sorts of π-conjugated systems, polydiacetylene and tetrathiafulvalene, were regularly assembled in a “hybrid” organic crystal using the solid-state polymerization of the corresponding diacetylene monomers. The absorption spectra and the electro-conducting properties of the polydiacetylene obtained as a “hybrid” crystal were reported.

ISSN:1058-725X    

DOI:10.1080/10587259808044314

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The chiral and nonlinear optical properties of polymeric Langmuir-Blodgett films are investigated

ISSN:1058-725X    

DOI:10.1080/10587259808044315

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Recently, amorphous organic photorefractive (PR) materials have attracted a lot of attention. However, since most of the high-performance PR organic materials are polymers blended with large amounts of low-molecular-weight components, their shelf-life time is limited due to phase separation. One way to improve the shelf-life time, which was proposed by us recently, is to use eutectic mixtures of two electrooptically active chromophores. However, in our earlier attempt in improved life time was achieved at the cost of a reduced performance due to increased absorption. In this paper, we apply this technique again with great success, not only improving the life time by a factor of 15, but at the same time improving the steady-state holographic performance by 30%.

ISSN:1058-725X    

DOI:10.1080/10587259808044316

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

It was found that the electric conductivity of both polymer film and substrate were critical factors for the preparation of a poled polymer using corona-poling technique. The polymer used in this study was a copolymer of 4-[N-(2-maleimidoethyl)N-methylarnino]-4′-nitroazobenzene (MENA) and α-metylstyrene, which has a large optical nonlinearity and high glass transition temperature (Tg). The highest possible dipolar orientation could be achieved by optimizing the electric resistance of the substrate (Rs) corresponding to the electric properties of the polymer, i.e., the electric conductivity and breakdown threshold. For example, the poled polymer prepared onto a 0.4 mm-thick soda glass (Rs = 0.45 GΩ at 160 °C) exhibited a large SHG coefficient (d33) of 268 × 10−9e.s.u., which is ∼70% larger than that for a 1.2 mm-thick soda glass (Rs = 1.4 GΩ at 160 °C).

ISSN:1058-725X    

DOI:10.1080/10587259808044317

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Novel organic/inorganic heterostructures composed of phthalocyanato tin(IV) dichloride (SnCl2Pc) and cadmium selenide (CdSe) were fabricated by using of molecular beam deposition (MBD). By means of some structural analyses (XRD, TEM), the crystalline and multilayered structure of the deposited film was verified. Linear and nonlinear optical properties of the heterostructure were also measured, by which the third-order nonlinear optical susceptibility and two components of response time for the multilayers was estimated as 1.8×10−8esu, less than 80 fsec, and 5 psec, respectively. The processability and its good optical performance of this organic/inorganic heterostructure is exploring toward a new kind of optoelectronic switching material.

ISSN:1058-725X    

DOI:10.1080/10587259808044318

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We report third-order nonlinear optical properties of a stable radical species, 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-l-oxyl (PTIO). The nonresonant values of second hyperpolarizabilities measured by femtosecond Z-scan method at 780–857 nm were found to be negative. Wavelength dispersion of the hyperpolarizabilities is discussed referring to the theoretical predictions.

ISSN:1058-725X    

DOI:10.1080/10587259808044319

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Gain dynamics such as signal wavelength dependence and pump wavelength dependence for organic dye-doped graded index (GI) polymer optical fiber amplifiers (POFA) are characterized. A Rhodamine B-doped POFA, 1 m in length and 0.3 mm in core diameter, has exhibited more than 20 dB gain at signal wavelengths from 560 nm to 600 nm when optically pumped at 532 nm. The maximum gain of 37 dB was achieved with a Rhodamine B-doped POFA pumped at 550 nm, which was optimum pump wavelength. For an Oxazine 4-doped POFA, signal gain of 20 dB was obtained when pumped at 605 nm. It is shown that pumping at absorption maximum wavelengths optimizes amplifier performance.

ISSN:1058-725X    

DOI:10.1080/10587259808044320

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Novel polydiacetylene (PDA) derivatives were prepared from the monomers that have two butadiyne parts linked by a methylene chain and their both ends were modified by butoxycarbonylmethyl urethane groups. Polymerization in solid state was performed by UV or γ-ray irradiation and characteristic excitonic absorption of PDA was observed at around 635 nm except for one compound (574 nm). From13C NMR spectra measured using CP/MAS and from X-ray diffraction experiment, it was clear that the spacer containing four or more methylene groups is needed to form the ladder polymer composed of two PDAs linked by methylene chains, while eight methylene groups in the spacer are necessary to preserve its polymer crystallinity.

ISSN:1058-725X    

DOI:10.1080/10587259808044321

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Of 140 newly synthesized chalcone-analogous materials, 56 specimens were observed to be efficient for nonlinear optical second harmonic generation (SHG). The SHG efficiency of 3-(4-chlorophenyl)-1-(3-pyridyl)-2-propen-1-one is discussed on the basis of crystal structure and MO calculation. In this crystal, molecules arrange themselves almost ideal manner for SHG.

ISSN:1058-725X    

DOI:10.1080/10587259808044322

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor