• Korean Journal of Optics and Photonics
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• v.18 no.3
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• pp.216-220
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• 2007

A widely tunable add/drop filter composed of double ring resonators is implemented with high-index-contrast polymer waveguide. To enhance the productivity, directional couplers are designed to have good fabrication tolerance. The refractive indices of the core and cladding in the 1550 nm wavelength are 1.51 and 1.378, respectively. Drop response in comparison with neighborhood peak gets enhanced by more than 2.9 dB at the wavelength where both rings resonate. This filter can be used to build widely tunable laser diode through hybrid-integration with reflective SOA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.840-843
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• 2012

In this paper, the authors present a new design for a dual-band metamaterial(MTM) absorber that utilizes resonant-magnetic inclusion of a split-ring resonator(SRR). The proposed MTM unit cell is constructed by two open complementary split-ring resonators(OCSRRs) and an SRR arrangement. To avoid the need for metallic back plate a planar array of SRRs for resonant-magnetic inclusion is placed facing toward the incident wave propagation direction. Each unit cell is printed on the two sides of a FR-4 substrate. A prototype absorber was fabricated with a planar array of $39{\times}39$ unit cells, and measured. The proposed backplane-less absorber can be used for microwave applications.

• Journal of Navigation and Port Research
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• v.34 no.7
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• pp.543-552
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• 2010

Modified compact combline bandpass filters are proposed based on the miniaturized quarter-wave transmission line which is composed of the parallel coupled line and lumped capacitors. The electrical length of the parallel coupled line in a resonator, which determines the size of combline bandpass filters, is just $5^{\circ}$ or $7^{\circ}$, resulting in a compact circuit area. The designed combline bandpass filter also has a wide upper stopband by suppressing the spurious passbands, not moving. Measured results of two fabricated filters centered at 400MHz show good agreement with the theoretical predications.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.438-443
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• 2010

In this paper, behaviors of photonic crystal (PC) radiative structures and antenna arrays have been compared for two types of uniform and binomial excitations. Appropriate duality has been shown between them. These results can be generalized to other types of excitation and arrangement of photonic crystal radiative arrays such as linear, planar and circular arrays of three dimensional (3D) photonic crystal termination resonators. Using these results in designing photonic circuits has some advantages for shaping a particular radiative beam at the photonic crystal exit, for instance reducing the divergence angle of the main lobe in order to enhance the directivity, for better coupling, or for splitting the emitted beam, for dividing the output beam to the next devices in photonic integrated circuits (PIC). For analysis and simulation of the photonic crystal structures, the finite difference time domain (FDTD) method has been employed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.570-572
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• 2012

In this paper, a three-dimensional (3-D) low-loss and wide-band BPF based on low-temperature co-fired ceramic (LTCC) has been presented for mm-wave wireless communication applications. The proposed BPF is designed in a 6-layer LTCC substrate. The double patch resonators are fully integrated into the LTCC dielectrics and vertical via and planar CPW transitions are designed for interconnection between embedded resonators and in/output ports and MMICs, respectively. The designed BPF was fabricated in a 6-layer LTCC dielectric. The fabricated BPF shows a centre frequency (fc) of 53.23 GHz and a 3dB bandwidth of 14.01 % from 49.5 to 56.9 GHz (7.46 GHz). An insertion loss of -1.56 dB at fc and return losses below -10 dB are achieved. Its whole size is $4.7{\times}1.7{\times}0.684mm^3$.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.665-672
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• 2015

We demonstrate an ultrathin metamaterial for polarization independent perfect absorption as well as a band-pass filter (BPF) which works at a higher frequency band compared to the perfect absorption band. The planar metamaterial is comprised of three layers, symmetric split ring resonators (SSRRs) at the front and structured ground plane (SGP) at the back separated by a dielectric layer. The perfect metamaterial absorber (MA) can realize near 100% absorption due to high electromagnetic losses from the electric and/or magnetic resonances within a certain frequency band. The thickness of the structure is only 1/28 of the maximum absorption wavelength.

• ETRI Journal
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• v.32 no.1
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• pp.148-150
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• 2010

This letter presents the design of a compact bandstop filter (BSF) operating at two frequencies. The proposed BSF consists of open-ended stepped impedance resonators (OSIR) and an end-shorted parallel-coupled microstrip line (E-PCML). The OSIRs are used to achieve the impedance-controlled stopband positions. The wide BSF bandwidths are achieved through enhanced coupling of the E-PCML. Explicit design guidelines are derived using a lossless transmission line model. To validate theoretical predictions, a prototype dual-band BSF operating at 900 MHz and 2,100 MHz with fractional bandwidths of 72% and 36%, respectively, is implemented in microstrip.

• Proceedings of the Korean Magnestics Society Conference
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• 2017.05a
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• pp.97-98
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• 2017

• Journal of electromagnetic engineering and science
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• v.8 no.1
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• pp.12-16
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• 2008

In this paper, we introduce a coupling, which is achieved through the aperture instead of the conventional edge coupling, so that the bandpass filter is reduced less than half in size compared to conventional planar type. The resulting filter configuration has a near two-fold symmetry, where the aperture coupling is used in the middle of the coupling stages. We designed a bandpass filter using two tapped hairpin resonators, of which the order becomes four. The designed bandpass filter has the size of $8.9{\times}18.3\;mm$. It has the return loss better than 17dB and the insertion loss of less than 5 dB in overall passband. The measured results show good agreements with simulated ones.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.53-62
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• 1999

Micro polysilicon actuators, which are widely used in the field of MEMS (Microelectromechanical System) technology, were fabricated using polysilicon thin layers. Polysilicon deposition were carried out to have symmetrical layer structures with a LPCVD (Low Pressure Chemical Vapor Deposition) system, and we have measured physical characteristics by micro test patterns, such as bridges and cantilevers to verify minimal mechanical stress and stress gradient in the polysilicon layers according to the methods of mutilayer deposition, doping, and thermal treatment, also, analyzed the properties of each specimen, which have a different process condition, by XRD, and SIMS etc.. Finally, the fabricated planar polysilicon resonator, symmetrically stacked to $6.5{\mu}m$ thickness, showed Q of 1270 and oscillation ampitude of $5{\mu}m$ under DC 15V, AC 0.05V, and 1000 mtorr pressure. The developed micro polysilicon resonator can be utilized to micro gyroscope and accelerometer sensor.