• ETRI Journal
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• v.24 no.4
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• pp.259-269
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• 2002

Polymers are emerging as new alternative materials for optical communication devices. We developed two types of polymer-based devices for optical communications. One type is for ultra high-speed signal processing that uses nonlinear optical (NLO) polymers in such devices as electro-optic (EO) Mach-Z${\ddot{e}} $ hnder (MZ) modulators and EO 2${\times}$2 switches. The other is for WDM optical communications that use low-loss optical polymers in such devices as 1${\times}$2, 2${\times}$2, 4-arrayed 2${\times}$2 digital optical switches (DOSs) and 16${\times}$16 arrayed waveguide grating (AWG) routers. For these devices, we synthesized a polyetherimide-disperse red 1 (PEI-DR1) side chain NLO polymer and a low-loss optical polymer known as fluorinated polyaryleneethers (FPAE). This paper presents the details of our development of these polymeric photonic devices considering all aspects from materials to packaging.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.181-186
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• 2008

2,5-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (3) was prepared and polycondensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel T-type polyesters (4-6) containing the NLO-chromophores dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4-6 are soluble in common organic solvents such as acetone and N,N-dimethylformamide. They showed thermal stability up to 260 oC in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range 90-95 oC. The second harmonic generation (SHG) coefficients (d33) of poled polymer films at the 1064 nm fundamental wavelength were around 1.42 ´ 10-9 esu. The dipole alignment exhibited high thermal stability up to 5 oC higher than glass-transition temperature (Tg), and there was no SHG decay below 100 oC due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.148-149
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• 2000

유기 고분자는 기존 무기물질의 한계성을 감안해 볼 때, 전기 및 광학적 특성이 우수하여 이에 대한 연구가 매우 활발히 진행되고 있다. 이중에서 Azo 화합물은 특별한 물리적, 광학적 성질과 그 잠재적인 응용성 때문에 계속해서 지금도 많은 관심을 끌고 있다. 그래서 Azo 화합물은 액정과 함께 비선형 광학성질을 가지는 물질에 응용될 수 있으며, 또한 광 유도현상의 이색성(dichroism)및 복굴절(birefringence) 현상 같은 특성을 나타내고 있다.$^{l)2)3)}$ 선형 광학 실험중에서 단순 입사 방법$^{4)}$ 을 이용하여 전기 광학 계수를 측정하였으며, 다시 확장 지수함수(stretched exponential)모델$^{5)}$ 로써 극화(poling)와 완화(relaxation)의 꼴을 보았다. (중략)

• Macromolecular Research
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• v.8 no.3
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• pp.137-141
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• 2000

3,4-Di-(2'-hydroxyethoxy)-4-nitrostilbene (2) was prepared by the reaction of 2-iodoethanol with 3,4-dihydroxy-4-nitrostilbene (1). Diol 2 was condensed with 2,4-toluenediisocyanate ,3,3-dimethoxy-4,4'-biphenylenediisocyanate , and 1,6-hexamethylenediisocyanate to yield polyurethanes 3, 4, and 5 containing the NLO-chromophore. Polymers 3-5 were soluble in common organic solvents such as acetone and DMSO. The glass transition temperatures(T$\sub$g/) of the resulting polymers 3-5 were obseved around 100-114$^{\circ}C$. Electrooptic coefficients (r$\sub$33/) of the poled polymer films were in the range of 18-25 pm/V at 633 nm. Polymers 3-5 began to decompose around 250$^{\circ}C$ in TGA thermograms.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.4-5
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• 2001

Advent of lasers offering high intensity beam has opened the glass to the nonlinear optic (NLO). The high electric field associated with such laser beams can be so large that high order components of the glass polarization can be measured. Such development is of scientific and technological interests in particular in systems involving an intensity-dependent refractive index and/or ultra-fast response (＜10$\^$-12/s). From a scientific viewpoint the NLO response intensity must be understood as a function of the glass composition. On the other hand, large family of applications are presently under investigation in various fields of optical materials or systems e.g. laser glasses for fusion energy, soliton propagation for ultra-long distances, ultra-fast-switching, optical storage etc....(omitted)

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1900-1906
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• 2012

Three carbazole chromophores featuring dicyano, cyano, ethyl acetate and dimethyl acetate groups as an acceptor moiety with a ${\pi}$-conjugated spacer and $N$-methyl dibenzo[$b$]pyrole as donor were synthesized by Knovenagel condensation and characterized by IR, $^1HNMR$, $^{13}CNMR$, UV-vis, fluorescence spectroscopy, electrochemistry and theoretical B3LYP/6-$311G^*$ level whilst NLO properties and spectroscopic quantities were calculated. Calculations showed remarkable trend with HOMO located on the donor moiety and LUMO on the acceptors dicyano methylene, cyano, ethyl acetate methylene and dimethyl acetate methylene. In agreement with the calculations, solvatochromic, behavior intramolecular charge transfer band was observed in the visible region.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.567-572
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• 1999

5-Nitro-2-(2'-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 5-nitro-2-(2'-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3-nitro-4-(2'-vinyloxyethoxy)benzylidenemalononitrile (4a), methyl 3-nitro-4-(2'-vinyloxyethoxy)benzylidenecyanoacetate (4b), 2-nitro-5-(2'-vinyloxyethoxy)benzylidenemalononitrile (6a), and methyl 2-nitro-5-(2'-vinyloxyetboxy)benzylidenecyanoacetate (6b) were prepared by the condensation of 5-nitro-2-(2'-vinyloxyethoxy)benzaldehyde (1), 3-nitro-4-(2'-vinyloxyethoxy)benzaldehyde (3), and 2-nitro-5-(2'-vinyloxyethoxy)benzaldehyde (5) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether monomers 2a-b, 4a-b, and 6a-b were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ethers) 7-9 having oxynitrobenzylidenemalononitrile and oxynitrobenzylidenecyanoacetate, which is effective chromophore for second-order nonlinear optical applications. Polymers 7-9 were soluble in common organic solvents such as acetone and DMSO. Tg values of the resulting polymers were in the range of 67-83 ℃. Electrooptic coefficient (r33) of the poled polymer films were in the range of 15-27 pm/V at 633 nm. Polymers 7-9 showed a thermal stability up to 300 ℃ in TGA thermograms, which is acceptable for NLO device applications.

• Bulletin of the Korean Chemical Society
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• v.17 no.7
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• pp.607-612
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• 1996

A series of new NLO-active poly(4-nitrophenylallylamine) derivatives was synthesized by the nucleophilic substitution reaction of several substituted 4-nitrohalobenzenes and poly(allylamine hydrochloride). All polymers obtained were amorphous and their glass transition temperatures (Tg) were observed around 148-160 ℃. For each of these polymers, their specific Tg values were dependent on characteristic electronic structures. UV-visible absorption spectra showed maximum absorption intensity at 355-393 nm for π-π* transition of alkylaminonitrophenyl groups. The χ(2)value of poly(4-nitrophenylallylamine), as determined by the second harmonic generation at 1064 nm, for a thin polymer film poled at an elevated temperature, was 1.4x10-8esu. The third-order NLO properties of poly(4-nitrophenylallylamine) derivatives were evaluated through measurement of degenerate four-wave mixing technique and χ(3) coefficient in the range of 2.7~3.2x10-12 esu at 602 nm was found with 400 fs laser pulses.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1053-1056
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• 2012

Location information is considered to be of prime importance in Vehicular Ad Hoc NETworks (VANETs) because important decisions are made based on accurate and sound location information. Vehicles exchange their whereabouts in the form of scheduled beacon messages with their neighbors. These messages contain location, speed, time, and lane information etc. In this paper we aim at the location security in VANET and emphasize on the confidentiality and integrity of location information in case of Nonline-of-Sight (NLoS). For location confidentiality we propose a geolock-based mechanism whereas for location integrity we leverage cooperation among neighbors. In case of NLoS, the verifier vehicle asks its one-hop neighbors in an efficient way to verify the claimed location of the node on his behalf. On the basis of trust values and weightage assigned to neighbors, it is decided whether the verification is sound.

• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.155-159
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• 1998

o-(2-Vinyloxyethoxy)benzylidenemalononitrile (4a), methyl o-(2-vinyloxyethoxy)benzylidenecyanoacetate (4b), m-(2-vinyloxyethoxy)benzylidenemalononitrile (5a), methyl m-(2-vinyloxyethoxy)benzylidenecyanoacetate (5b), p-(2-vinyloxyethoxy)benzylidenemalononitrile (6a), and methyl p-(2-vinyloxyethoxy)benzylidenecyanoacetate (6b) were prepared by the condensation of o-(2-vinyloxyethoxy)benzaldehyde (1), m-(2-vinyloxyethoxy)benzaldehyde (2), and p-(2-vinyloxyethoxy)benzaldehyde (3) with malononitrile or methyl cyanoacetate, respectively. Bifunctional vinyl ether monomers 4a-b and 6a-b polymerized readily with cationic initiators to give polymers with the NLO-chromophores o- and p-oxybenzylidenemalononitrile or o- and p-oxybenzylidenecyanoacetate in side chain at -60 ℃, while meta-isomers 5a and 5b gave lower yields of polymers under the same conditions. The resulting polymers 7-9 were soluble in common organic solvents and the inherent viscosities of polymers were in the range of 0.20-0.30 dL/g in acetone. Solution-cast films were clear and brittle, showing Tg values in the range of 40-70 ℃.