• 한국정밀공학회지
• /
• 제22권12호
• /
• pp.16-21
• /
• 2005

Photonic crystals, periodic structure with a high refractive index contrast modulation, have recently become very interesting platform for the manipulation of light. The existence of a photonic bandgap, a frequency range in which the propagation of light is prevented in all directions, makes photonic crystal very useful in application where the spatial localization of light is required, for example waveguide, beam splitter, and cavity. However, the fabrication of 3 dimensional photonic crystals is still difficult process. A concept that has recently attracted a lot of attention is a planar photonic crystal based on a dielectric membrane, suspended in the air and perforated with two dimensional lattice of hole. The fabrication of Si master with pillar structure using hot embossing process is investigated for two dimensional, low-index-contrast photonic crystal waveguide. From our research we show that the multiple stamp copy process proved to be feasible and useful.

• Current Optics and Photonics
• /
• 제2권1호
• /
• pp.47-52
• /
• 2018

We systematically investigated the negative-refraction effect for both TE and TM polarizations in annular photonic crystals. Since two polarization waves are excited in different bands, they result in different refractive angles, and so polarization beam splitters can be made of annular photonic crystals. It was found that, in comparison to normal square-lattice air-hole photonic crystals, annular photonic crystals have a much wider common frequency band between TE-1 and TM-2, which is quite beneficial to finding the overlap between the negative-refraction regions belonging to TE-1 and TM-2 respectively. Further analyses of equifrequency surfaces and the electric-field distribution of annular photonic crystals with different parameters have not only demonstrated how the filling factor of annular cells affects the formation of the common negative-refraction region between TE-1 and TM-2, but also revealed some ways to improve the performance of a polarization beam splitter based on the negative-refraction effect in an annular photonic crystal.

• Journal of the Optical Society of Korea
• /
• 제7권1호
• /
• pp.34-37
• /
• 2003

Outside the photonic bandgap of two-dimensional square lattice photonic crystals, we found spectral regions in which light coupling from the air is forbidden. This uncoupling spectral region originates from the anisotropy of the photonic crystals. A two-dimensional square photonic crystal has a complete total bandgap (forbidden region in both TE and TM modes) with hole radius ranging from 0.15 to 0.45 times a lattice constant.

• Journal of Electrical Engineering and Technology
• /
• 제3권2호
• /
• pp.276-279
• /
• 2008

We report on the enhancement of cathode-luminescence in an $In_xGa_{1-x}N/In_yGa_{1-y}$ green light emitting diode structure using two-dimensional photonic crystals. The square lattice arrays of photonic crystals with diameter/periodicity of 200/500 nm were fabricated by electron beam lithography. Inductively coupled plasma dry etching was used to etch and define photonic crystals. Three samples with different etch depths, i.e., 170, 95, and 65 nm, were constructed. Field emission scanning electron microscope analysis shows that air holes of photonic crystal structure with inverted-cone shapes were fabricated after dry etching. Cathode-luminescence measurement indicated that up to 30-fold enhancement of cathode-luminescence intensity has been achieved.

• 한국전기전자재료학회논문지
• /
• 제22권1호
• /
• pp.61-66
• /
• 2009

Characteristics of the photonic bandgaps (PEGs) in two-dimensional photonic crystals (2D PCs) with a square lattice have theoretically studied using a finite difference time domain (FDTD) simulation. In this paper, we propose a concept of optical coverage ratio (OCR) as a new structural parameter to determine the PEGs for E-polarized light. The OCR is an optically compensated filling factor. It is possible to normalize the PEGs of 2D PCs by introducing the OCR.

• 한국전기전자재료학회논문지
• /
• 제16권6호
• /
• pp.515-521
• /
• 2003

There are now many theoretical investigations and real manufactures for numerous applications of photonic crystals (PCs) associated with photonic band gap and photonic integrated circuits. However, there are some difficulties to design and fabricate the desired pattern quality. It is not easy to satisfy accurate critical dimension (CD) for patterns with arbitrary shapes and pitch sizes aligned in various directions. In this work, we report the optimum conditions to better fabricate and design, and greatly improve pattern quality in delineating two-dimensional (2D) PCs in the nanometer range using single- step e-beam lithography system with conventional exposure mode.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.498-501
• /
• 2005

Photonic crystals, periodic structure with a high refractive index contrast modulation, have recently become very interesting platform for manipulation of light. The existence of a photonic bandgap, a frequency range in which propagation of light is prevented in all direction, makes photonic crystal very useful in application where spatial localization of light is required for waveguide, beam splitter, and cavity. But fabrication of 3 dimensional photonic crystal is still difficult process. a concept that has recently attracted a lot of attention is a planar photonic crystal based on a dielectric membrane, suspended in the air, and perforated with 2 dimensional lattice of hole. We show that the polymer slabs suspended in air with triangular lattice of air hole can exhibit the in-plane photonic bandgap for TE-like modes. The fabrication of Si master with pillar structure using hot embossing process was investigated for 2 dimensional low-index-contrast photonic crystal waveguide.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제7권1호
• /
• pp.56-65
• /
• 2007

This paper describes physical meanings of various influences of cavity (or pillar) shape and filling factor of dielectric material on band structures in two-dimensional photonic crystals. Influences of circular and rectangular cross-sections of cavity (or pillar) arrays on photonic band structures are considered theoretically, and significant aspects of square and triangular lattices are compared. It is shown that both averaged dielectric constant of the photonic crystal and distribution profile of photon energy play important roles in designing optical properties. For the triangular lattice, especially, it is shown that cavity array with a rectangular cross-section breaks the band structure symmetry. So, we discuss this point from the band structure and address optical properties of lattice with a circular cross-section cavity.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.38-38
• /
• 2009

Characteristics of the photonic bandgaps (PBGs) in two-dimensional photonic crystals (2D PCs) with a hexagonal lattice have theoretically studied using a finite difference time domain (FDTD) simulation. In this research, we propose a concept of optical coverage ratio (OCR) as a new structural parameter to determine the PBGs for E-polarized light. The OCR is an optically compensated filling factor. It is possible to normalize the PBGs of 2D PCs by introducing the OCR.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.270-272
• /
• 2003

We have investigated the coupling characteristics of localized modes of line defect i.e., guided modes, in photonic crystals. The parity of the coupled guided modes is not conserved when the distance between the line defects changes. By comparing the coupling characteristics of localized modes without the oscillatory nature such as cavity modes of metallic Fabry-Parot cavities with those of localized modes in photonic crystals, we confirmed that this parity nonconservation is attributed to the oscillatory nature of the evanescent waves of localized modes in photonic crystals.