Tae Hyung Rhee

Synthesis of fluorinated polyimides and their application to passive optical waveguides

Fluorinated and chlorofluorinated polyimides with high thermal stability and low optical absorption loss in the optical communication wavelengths of 1.3 and 1.55 μm were investigated for low-loss passive waveguide applications. These polyimides were prepared from pyromellitic dianhydride (PMDA) with 1,4-bis-[4-amino-2-(trifluoromethyl)phenoxy]tetrafluorobenzene (ATPT), 1,4-bis-[4-amino-2-(trifluoromethyl)phenoxy]benzene (ATPB), and 1,3-bis-[4-amino-2-(trifluoromethyl)phenoxy]-4,6-dichlorobenzene (ATPD). Control of the refractive indices of the polymers was achieved from 1.5397–1.5671 for TE polarization and 1.5239–1.5513 for TM polarization at 1.55 μm by copolymerization of PMDA/ATPT and PMDA/ATPB. As the amount of PMDA/ATPT was increased, the refractive indices of the polymers were decreased. Rib-type optical waveguides were fabricated using these fluorinated polyimides. These waveguides exhibited a low propagation loss of less than 0.5 dB/cm at 1.55 μm.

Low‐loss passive polymer waveguides by using chlorofluorinated polyimides

Chlorofluorinated polyimides were prepared from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (PFMB), and 2,2′-dichloro-4,4′-diaminobiphenyl (DCB) for optical waveguide applications. The resulting optical polymers exhibited good thermal stability, controllable refractive index, and low optical loss in the optical communication wavelengths of 1.3 and 1.55 µm. The control of refractive indices of the polymers was achieved by copolymerization of 6FDA/PFMB and 6FDA/DCB. As the amount of DCB was increased, the refractive indices of polymer were increased. The effect of addition of chlorine on optical properties of polymers such as absorption loss in the near-IR region were also investigated. Rib-type optical waveguides were fabricated using these chlorofluorinated polyimides. These waveguides exhibited low loss of less than 0.4 dB/cm for both TE and TM polarizations.

Synthesis and properties of chlorinated polyimides

Full paper: A series of diamines with various chlorine content was synthesized. Using these novel diamines, a series of new chlorinated polyimides was prepared by reacting them with 2,2-bis(3,4-dicarboxyphenyl)hexa-fluropropane dianhydride (6FDA). The purpose was no investigate the effect of the chlorine content on the proerties of polyimides, such as thermal and optical properties. The in-plane refractive (n te ) indices of polymer films increase with increasing order of in-plane orientation in these polyimides. The out-of-plane refractive (n tm ) indices increase with chlorine content.

Chloro-Fluorinated Polyimides for Low Loss Optical Waveguides Application.

Optical polymers which exhibit good thermal stability, controllable refractive index, and low optical loss in the optical communications wavelength of 1.55 µm were prepared using fluorinated and chloro-fluorinated polyimides. As the chlorine moiety is increased, the refractive indices of polymer are increased from 1.5176 to 1.5714 for TE polarization and from 1.5076 to 1.5590 for TM polarization at 1.55 µm. Single mode rib type polymer optical waveguides were fabricated using fluorinated and chloro-fluorinated polyimides. These waveguides exhibit a low propagation loss of less than 0.4 dB/cm at 1.55 µm, and a very low polarization dependent loss of less than 0.01 dB/cm.

Soluble and Processable Poly(p-phenylene) with Pendant Imide Groups

We have investigated a soluble and processable poly(p-phenylene) (PPP) having two pendant imide groups. A novel π-conjugated PPP was prepared by dehalogenation polycondensation of a dibromo aromatic compound with a zerovalent nickel (Ni(0)) complex. The monomoer and polymer were characterized by 1 H NMR, FT-IR, elemental analysis, TGA, and DSC. The resulting polymer showed a good solubility in polar aprotic solvents such as DMAc, DMSO, and NMP. This polymer was also easily cast on a glass plate to give an orange-yellow film. The polymer showed a high glass transition temperature of 295°C. The present polymer exhibited photoluminescence with a maximum band at 553 nm in DMAc solution.

Four-branch single-mode waveguide power divider

A 1/spl times/1 power divider based on the four-branch single-mode waveguide is proposed and fabricated. The proposed structure has one beam separator and two beam expanders in the branching region. The uniform output power distribution can be obtained by adjusting the sizes of the beam separator and the beam expander. The measured powers of four output ports are uniform for both TE and TM modes within the difference of 0.3 dB. The effects of the beam separator and the beam expander on the power dividing ratio and the scattering loss of the proposed device are also discussed.

Athermal AWG Multiplexer/Demultiplexer for E/C-band WDM-PON application

Athermal AWG multiplexer/demultiplexer prepared for E/C-band WDM-PON application, by a novel and practical psudo-passive alignment packaging method, demonstrates <plusmn30 pm center wavelength shifts at ITU grids over the widest operating temperature range of -40degC~+80degC.

1/spl times/4 thermo-optic switch based on the 4-branch waveguide

In this paper, we demonstrate a 1/spl times/4 thermo-optic switch based on the 4-branch waveguide. The proposed structure has one beam separator and two beam expanders in the branch region of a 4-branch waveguide and four electrodes as heaters on the top of each branch. The operation of this device is based on adiabatic mode evolution in branch waveguides with a small angle of separation. The integration of this 4-branch switch as a unit cell offers advantages in realizing matrix switches with many output ports.

Chloro-Fluorinated Poly(arylene ethers) for Optical Waveguide Application

Abstract Optical polymers which exhibit good thermal stability, refractive index controllability, and low optical loss in the optical communication wavelengths were developed by using chloro-fluorinated poly(arylene ethers).

Polymeric Optical Waveguides using Fluorinated Polyimides

Abstract Fluorinated polyimides with high thermal stability and low optical absorption loss have been investigated for waveguide application. Rib-type optical waveguides were fabricated using these fluorinated polyimides.