• Current Optics and Photonics
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• 제2권4호
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• pp.303-307
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• 2018

We propose a simple ultraviolet (UV) sensor consisting of a conventional single-mode optical fiber capped with an azobenzene-moiety-containing polymer. The UV light changes the dimensions of the azobenzene polymer, as well as the refractive index of the material. Incident light with a wavelength of 1550 nm was reflected at the fiber/polymer and polymer/air interfaces, and interference of the reflected beams resulted in spectral interference that shifted the wavelength by 0.78 nm at a UV input power of $2.5mW/cm^2$. The UV sensor's response to wavelength is nonlinear and stable. The response speed of the sensor is limited by detection noise, which can be improved by modifying the insertion loss of the UV sensor and the signal-to-noise ratio of the detection system. The proposed compact UV sensor is easy to fabricate, is not susceptible to electromagnetic interference, and only reacts to UV light.

• 대한화학회지
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• 제37권1호
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• pp.62-67
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• 1993

Quinoline계 화합물인 미시적 비선형 광학 특성을 설명하기 위해 반경험적인 AMI 방법을 사용하여 초분극률을 계사하였다. Quinoline 고리에서 이차 비선형 특성에 기여하는 전자공여체, 아미노기와 전자수여체, 니트로기의 반응 위치를 변경하여 미시적 비선형 상수에 대한 이론적 영향을 조사해 보았다. 이차와 삼차 비선형 주쇄고분자로서 물리적, 기계적 성질이 우수한 polyquinoline계 고분자를 이용하기 이해 polyquinoline계 반복단위와 유사한 단분자 quinoline들을 설계하여 각각의 미시적 비선형 상수 및 바닥상태의 쌍극자 모멘트 등을 유한 전기장하에서 계산하여 서로 평가 비교해 보았다.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 하계학술발표회
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• pp.88-89
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• 2004

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 하계학술발표회
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• pp.164-165
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• 2000

There has recently been a considerable amount of interest in two-photon(TP) processes because of their applications to 3-D optical data storage and imaging, up-conversion lasing, and optical power limiting. Recently, the role of Dithienothlophene(DTT) as $\pi$-center of two-photon absorption(TPA) molecules was reported to give a large enhancement of TPA, compared with the benzeniods counterparts.$^{[1]}$ In this report, we carried out two experiments to investigate nonlinear optical absorption of the molecules in which central DTT is attached through conjugation to either a D/D or a D/A pair at the ends, forming a D-$\pi$-D(1 and 3) or D-$\pi$-A(2 and 4) sequence(Fig.1). All the samples were prepared in solutions with the same molar concentration. (omitted)

• Macromolecular Research
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• 제15권6호
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• pp.506-512
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• 2007

2,3-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (3) was prepared and condensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel Y-type polyesters (4-6) containing the NLO-chromophores 2,3-dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4-6 were soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymers 4-5 showed thermal stability up to $300^{\circ}C$ in thermogravimetric analysis with glass transition temperatures $(T_g)$, obtained from differential scanning calorimetry, in the range $81-95^{\circ}C$. The second harmonic generation (SHG) coefficients $(d_{33})$ of the poled polymer films at the 1064 nm fundamental wavelength were around $3.68{\times}10^{-9}$ esu. The dipole alignment exhibited high thermal stability up to $T_g$, and there was no SHG decay below $T_g$ due to the partial main-chain character of the polymer structure.

• Bulletin of the Korean Chemical Society
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• 제19권11호
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• pp.1168-1171
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• 1998

Two kinds of second-order nonlinear optical copolymers were prepared by the copolymerization of the vinyl monomers containing NLO chromophore, methacrylic acid, and methyl methacrylate or butyl methacrylate. Glass transition temperatures (Tg of copolymers were around 130 ℃. The copolymers were soluble in common organic solvents such as tetrahydrofuran (THF), cyclohexanone, and N,N-dimethylformamide (DMF). The crosslinked copolymer was obtained by thermal treatment using pentaerythritol tetrakis(2-mercaptoacetate) as a crosslinker and became insoluble in tetrahydrofuran (THF) and N,N-dimethylformamide (DMF). Poling was carried out at 120 ℃ for 20 min and identified with UV-Vis spectroscopy. Electro-optic coefficient (r33) measurement showed a value of 35 pm/V for polymer 2 at 633 nm. Temporal stability of copolymers was improved owing to the crosslinked network, which was successfully obtained at 170 ℃ for 30 min after poling.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.25-26
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• 2006

Azobenzene functionalized polymers have been extensively investigated due to the potential applications in the areas of optical switching, optical elements, optical information storage, and nonlinear optics. These applications are mainly achievable due to photoinduced properties of azobenzene groups with photoisomerization and photoinduced anisotropy. We report applications to the optoelectronic devices using inscribed one-(1D) and two-dimensional (2D) SRGs on azo polymer films. The inscribed holographic SRGs patterns were useful to control or enhance optoelectronic properties such as transparent electrode patterning, hybrid solar cell and ultraviolet GaN-based LED.

• Journal of Photoscience
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• 제12권2호
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• pp.95-100
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• 2005

We have synthesized an azobenzene-containing polymer (PEA) and a stilbene-containing polymer (PAS) with second-order nonlinear properties. The second harmonic coefficient ($d_{33}$) of the poled polymer films was 84 and 36 pm/V for of PEA and PAS, respectively. The poled state of these polymers was stable at least up to 30 h at room temperature. $T_g$ of these polymers appeared in the range from 120 to $160^{\circ}C$ and onset of initial weight losses in the range from 260 to $270^{\circ}C$. Silicon moieties in the main chain enhanced the solubility of PEA and PAS in common organic solvents such as chloroform, N-methylpyrrolidinone (NMP), N, N-dimethylformamide (DMF), etc.

• 한국진공학회지
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• 제12권S1호
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• pp.70-73
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• 2003

Sum-frequency vibrational spectroscopy has recently been used to investigate the surface of the various polymers and was able to find the chemical compositions and structures specific to the surface. Here we report our studies on two specific polymer samples to demonstrate its capability. Polyimide thin films were made by spin coating on fused quartz and $CaF_2$ substrates. The sum-frequency signal originating mainly from the air/polymer interface showed markedly different spectra, indicating the structural change of the polymer surface depending on the underlying substrate. Various polyethylene surfaces were also investigated by sum-frequency vibrational spectroscopy. The surface of polyethylene samples in the CH-region showed different sum-frequency spectra, presumably due to the trace amount of additives having much higher concentration at the air/polymer interface. These examples demonstrate the surface and interface of the polymer could have different structure and chemical composition from those of a bulk, which can be studied effectively by surface nonlinear optical spectroscopy.

• Macromolecular Research
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• 제12권6호
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• pp.581-585
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• 2004

A copolymer P[OSA-MI] was synthesized by copolymerization of its corresponding monomers, N-phenyl maleimide (MI) and 2-octen-l-ylsuccinic anhydride (OSA). The polymer (poly[2-[1-(2,5-dioxo-l-phenylpyrroli­din-3-ylmethyl)heptyl]-succinic acid 4-(2-$\{$ethyl-[4-(4-nitrophen-ylazo)phenyl]amino$\}$ethyl)ester]) P[DR1MA-MI] was obtained from the reaction of P[OSA-MI] with 2-[4-(4-nitrophenylazo)-N-ethylphenylamino] ethanol (DR1). A stable monolayer of P[DRIMA-MI] was formed by spreading the solution of the polymer in chloroform. In Y-type Langmuir-Blodgett (LB) films prepared using this Langmuir-Blodgett method, the second harmonic waves generated from adjacent mono layers canceled each other out. In X-and Z-type LB films, the second harmonic intensity increased upon increasing the number of monolayers, but this increase was somewhat smaller than predicted by the square law. This phenomenon is due to defects or imperfect alignment of the dipoles in the LB film. The generation of second harmonic waves from Y-type LB films having an even number of mono layers supports this argument. The degree of imperfection seemed to increase as the number of layers increased. The second-order nonlinear optical properties of spin-cast films of these polymers were also measured. The largest second harmonic coefficient of the poled P[DRIMA-MI] film coated on a glass plate was 19 pm/V.