Hyun-Shik Lee

Photonic crystal power-splitter based on directional coupling

We propose a new power-splitting scheme in two-dimensional photonic crystals that can be applicable to photonic integrated circuits. The proposed power-splitting mechanism is analogous to that of conventional three-waveguide directional couplers, utilizing coupling between guided modes supported by line-defect waveguides. Through the analysis of dispersion curve and field patterns of modes, the position in propagation direction, where an input field is split into a two-folded image, is determined by simple mode analysis. Based on the calculated position, a photonic crystal power-splitter is designed and verified by finite-difference timedomain computation.

Organic–inorganic hybrid materials for flexible optical waveguide applications

Novel organic–inorganic hybrid materials of 3-acryloxypropyl trimethoxysilane and 4,4′-(hexafluoroisopropylidene)diphenol were synthesized by non-hydrolytic sol–gel processing. Thick, crack-free films were produced by spin-coating without high volume shrinkage during further treatment of the films. The optical properties of the materials were precisely tailored by adjusting the chemical composition of the materials. The tunability of the refractive index allowed us to fabricate step-index optical waveguide structures with well-defined and reproducible refractive index differences to within 0.001. The relatively large, negative thermo–optic coefficients (dn/dT, °C) were obtained in the temperature range below 100 °C and displayed a systematic decrease with the addition of the organic compounds. Using these hybrid materials, we fabricated a flexible optical waveguide based on a soft-lithography technique. The bending loss of a flexible waveguide array was measured and found to yield no significant loss above 2 mm diameter curvature. The transmission performance of each waveguide channel was tested using a 10 Gbps data stream. The electrical output signal from a photodetector, connected to a wide-band oscilloscope, displays a clear 10 Gbps eye pattern.

A triplexer optical transceiver module using cascaded directional couplers

We present the design of a newly conceived triplexing optical microsystem that can provide bases for three wavelengths splitting function for gigabit passive optical network application. Three wavelengths consist of one for the upstream, 1310nm wavelength signal and the other two for downstream, 1490nm and 1550nm wavelength signal. The triplexer module is designed in the form of a planar optical integrated circuit using three directional couplers. In order to increase wavelength splitting performance we arrange the directional coupler by cascaded connecting method and use the asymmetric Y-branch. We analyzed its performance characteristics by BPM. The optical crosstalk of the 1310nm signal to the 1490nm signal and the 1550nm signal are -27.92dB and -66.83dB, respectively in the upstream. In the case of downstream the optical loss is less than 0.5dB with 20nm bandwidth and the optical crosstalk reaching less than -30dB in the downstream is 19nm.

Fabrication of a 45° microreflector-ended polymer waveguide using one-step UV embossing technique

This paper reports on a fabrication method of 45°-mirror-ended polymer waveguide using single-step UV embossing technique. This technique allows us to fabricate an array of twelve channel multimode polymer waveguides having 45°- mirrors during single-step UV embossing process. For the embossing process we have used a 45°-ended silicon waveguide mold. The silicon waveguide mold has a 45° slope prefabricated at the end of each waveguide structure. With this mold, UV embossing is performed to form undercladding and 45° mirror structures simultaneously. And a metal film is coated on the surface of the 45° slope. And then, core polymer is filled and cured by UV irradiation. By using this method, small size of micro mirror structures can be formed during waveguide fabrication process and fabrication steps can be reduced.

Design of compact silicon optical modulator using Photonic Crystal MZI structure

We designed a compact silicon optical modulator using photonic crystal(PhC) Mach-Zehnder interferometer(MZI), where we reduced the length of the modulator by using slow light phenomenon which causes effective phase difference in the MZI.

Nanofocusing of light using three-dimensional plasmonic mode conversion.

Efficient nanofocusing of light into a gap plasmon waveguide using three-dimensional mode conversion in a strip plasmonic directional coupler is proposed. Unlike conventional nanofocusing using tapering structures, a plasmonic directional coupler converts E(z)-type odd mode energy into E(y)-type gap plasmon mode by controlling phase mismatch and gap spacing. The simulation result shows the maximum electric field intensity increases up to 58.1 times the input intensity, and 17.3% of the light is focused on the nano gap region.

Design of compact silicon optical modulator using photonic crystal MZI structure

We designed a compact silicon optical modulator using photonic crystal(PhC) Mach-Zehnder interferometer(MZI), where we reduced the length of the modulator by using slow light phenomenon which causes effective phase difference in the MZI.

1053 TREATMENT WITH CLEVUDINE FOR 24 WEEKS RESULTS IN SUSTAINED ANTIVIRAL RESPONSE ASSOCIATED WITH CONTINUED HBsAg DECREASE 24 WEEKS POST-TREATMENT IN HBeAg-POSITIVE PATIENTS

viral replication, with mean maximum reductions in HCVRNA ranging from −0.97 to −2.13 (log10 IU/mL). In this study, the safety and efficacy of FBV in combination with pegylated interferon alfa-2a (pegIFN) and ribavirin (RBV) was evaluated. Methods: Eligible patients (treatment naive, HCV genotype 1) were randomized 1:1:1:1 to receive FBV (200, 300 or 500mg BID) or placebo in combination with pegIFN (180 ug/wk) and RBV (1000/1200mg/day) for 4 weeks. Patients are continuing on open label pegIFN/RBV for an additional 44 weeks. Results from the Week 4 analysis are described here. HCVRNA was measured using the Roche COBAS Taqman (LLD= 25 IU/mL). Results: A total of 35 patients were enrolled and 34 completed Week 4. The majority were Caucasian (69%), genotype 1a (80%) and male (51%). The most frequently reported AEs were headache, fatigue, insomnia and nausea. There were no trends towards increased frequency or severity of AEs with increasing dose of FBV. The incidence and severity of laboratory test abnormalities was similar across treatment groups. There was one treatment-related SAE (elevated creatinine) in the FBV 300mg group, which resolved following IV hydration. No other renal AEs were reported. The mean reduction (log10 IU/mL) in HCVRNA at Day 4 for placebo (n = 8), 200 (n = 10), 300 (n = 9) and 500 (n = 8) mg BID was −0.58, −2.29, −2.72 and −2.83, respectively, and −2.10, −4.46, −4.67 and −3.62 at Day 28. The percent of patients achieving RVR (undetectable HCVRNA by Week 4) for placebo, 200, 300 and 500mg BID was 0%, 60%, 75% and 63%, respectively. Of those patients treated with 200, 300 and 500mg BID who achieved a RVR, 33%, 33% and 80% achieved undetectable HCVRNA within two weeks of treatment, respectively. Conclusions: The addition of FBV to pegIFN/RBV was well tolerated and markedly increased the percentage of patients achieving RVR. Assessment of response to pegIFN/RBV therapy subsequent to Week 4 is ongoing.

Design of a silicon optical micro-ring resonator sensor of improved sensitivity and selectivity

We report on the successful design of a silicon micro-ring resonator for improved sensitivity and selectivity in the optical bio-sensing applications. By controlling the waveguide width w, the radius of the resonator R, and the waveguide separation S, we improved the sensitivity and the selectivity of the micro-ring resonator sensor. We obtained the sensitivity of 0.79nm/0.001, which is a 50% increase over the sensitivity without the reduction of the waveguide width. We obtained the selectivity of more than 3,000 with nearly 100% output intensity. We compared these results with the results obtained from the well-established Finite Difference Time Domain (FDTD) method and found that they are in excellent agreement with each other.

P988 SERUM INSULIN-LIKE GROWTH FACTOR-1 PREDICTS DISEASE PROGRESSION AND SURVIVAL IN PATIENTS WITH HEPATOCELLULAR CARCINOMA WHO UNDERGO TRANSARTERIAL CHEMOEMBOLIZATION

Background/Aim: Hepatocellular carcinoma (HCC) is a hypervascular tumor, and angiogenesis plays a pivotal role in tumor biology. Insulin-like growth factor (IGF) is an angiogenic factor that is implicated in the development and progression of various cancers. In the present study, we investigated the prognostic value of serum IGF-1 levels in HCC patients treated with transarterial chemoembolization (TACE). Methods: Consecutive HCC patients who had undergone TACE were included from a prospective cohort. The levels of serum IGF-1 and vascular endothelial growth factor (VEGF) were analyzed with regard to their associations with disease progression and survival. Results: A total of 155 patients were included. During a median follow-up period of 35.6 months, patients with IGF-1 levels in the lower three quartiles (≤ 125 ng/mL) had a significantly shorter TTP (median, 6.0 months) compared with patients in the highest quartile (> 125 ng/mL; median, 16.5 months; P=0.003). The hazard ratio (HR) of progression for each 10 ng/ mL decrease in IGF-1 level was 1.049 (P=0.007). The multivariate analysis revealed that low IGF-1 levels remained a signifi- cant risk factor for disease progression (for each 10 ng/mL decrease in IGF-1 level: HR, 1.062; P=0.004). Furthermore, together with tumor size, stage, serum VEGF level, and treat- ment response, low IGF-1 levels were an independent predictor of shorter OS (for each 10 ng/mL decrease in IGF-1 level: HR, 1.073; P=0.019). When we divided the patients into four groups according to baseline IGF-1 (< median or ≥ median) and VEGF (< median or ≥ median) levels, patients with low IGF-1 and high VEGF levels had a significantly increased risk of disease progression and death compared with patients in the other 3 groups (P=0.002 and <0.001, respectively). Conclusions: Low baseline IGF-1 levels independently correlated with shorter TTP and poorer OS in patients with HCC who underwent TACE.