• Journal of information and communication convergence engineering
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• 제13권1호
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• pp.50-55
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• 2015

We report design and simulation of a two-dimensional (2D) silicon-based nanophotonic crystal as an optical insulator to enhance the light emission efficiency of light-emitting diodes (LEDs). The device was designed in a manner that a triangular array silicon photonic crystal light insulator has a square trench in the middle where LED can be placed. By varying the normalized radius in the range of 0.3-0.5 using plane wave expansion method (PWEM), we found that the normalized radius of 0.45 creates a large band gap for transverse electric (TE) polarization. Subsequently a series of light propagation simulation were carried out using 2D and three-dimensional (3D) finite-difference time-domain (FDTD). The designed silicon-based light insulator device shows optical characteristics of a region in which light propagation was forbidden in the horizontal plane for TE light with most of the visible light spectrum in the wavelength range of 450 nm to 600 nm.

• 한국재료학회지
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• 제24권10호
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• pp.509-514
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• 2014

We demonstrate a simple and effective method to accurately position silicon nanowires (Si NWs) at desirable locations using drop-casting of Si NW inks; this process is suitable for applications in nanoelectronics or nanophotonics. Si NWs were assembled into a lithographically patterned sacrificial photoresist (PR) template by means of capillary interactions at the solution interface. In this process, we varied the type of solvent of the SiNW-containing solution to investigate different assembly behaviors of Si NWs in different solvents. It was found that the assembly of Si NWs was strongly dependent on the surface energy of the solvents, which leads to different evaporation modes of the Si NW solution. After Si NW assembly, the PR template was cleanly removed by thermal decomposition or chemical dissolution and the Si NWs were transferred onto the underlying substrate, preserving its position without any damage. This method enables the precise control necessary to produce highly integrated NW assemblies on all length scales since assembly template is easily fabricated with top-down lithography and removed in a simple process after bottom-up drop-casting of NWs.

• IEIE Transactions on Smart Processing and Computing
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• 제5권2호
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• pp.123-128
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• 2016

In this paper, an inversely tapered coupler with Bragg reflectors is reported for the first time. With appropriately positioned reflecting structures, our fiber-to-chip coupler can more efficiently transmit the light from fiber to a waveguide in a photonic integrated circuit (PIC). A numerical simulation evaluated the coupler's efficiency with the reflector. Optimized parameters that maximize the efficiency of the coupler are also investigated. Simulation results show that the reflector with appropriate parameters enhances efficiency by up to 7 dB. Likewise, Bragg metal reflectors implemented by the conventional metallization process can also improve efficiency. It is also shown that the proposed reflector enhances the coupling efficiency in a double-tip taper coupler.

• 한국광학회지
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• 제28권6호
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• pp.361-365
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• 2017

본 논문은 협대역의 플라즈모닉 흡수체 구현을 위한 금속 나노입자 주기구조 설계 및 제작에 관한 연구다. 제안된 플라즈모닉 흡수체의 상단 금속 나노입자는 주기적으로 홈이 파여있는 템플릿을 이용하여 전자빔 증착 후, 열처리하는 제작 기술로 형성하였다. 주기적 홈 템플릿 위에 제작된 금속 나노입자를, 따로 제작한 33 nm 두께의 $Al_2O_3$가 스퍼터 가공된 200 nm 두께의 금속 반사판-기판 상단에 옮기는 방법을 통해 플라즈모닉 흡수체를 제작하였다. 제작된 금속 나노입자는 평균 지름 46 nm, 주기 76 nm의 크기를 가졌다. 광학 측정 결과, 제작된 플라즈모닉 흡수체는 중심파장 572 nm, 반값전폭 109.9 nm의 플라즈모닉 공명 흡수를 나타내었다.