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61.
Design and fabrication of a significantly shortened multimode interference coupler for polarization splitter application 总被引:4,自引:0,他引:4
Jung Moo Hong Hyun Ho Ryu Soon Ryong Park Jae Wan Jeong Seung Gol Lee El-Hang Lee Se-Geun Park Deokha Woo Sunho Kim Beom-Hoan O 《Photonics Technology Letters, IEEE》2003,15(1):72-74
We report that we have successfully designed and fabricated a significantly shortened multimode interference coupler for application in polarization splitter, using a phenomenon that we termed "quasi-state" (QS) imaging effect. First, we identified and analyzed the QS imaging effect, and, based on the QS analysis, designed and fabricated a novel multimode interference (MMI) device with its split length shortened to 1/5 of a normally designed MMI split length. The fabrication is simple and cost effective and the fabricated device shows outstanding characteristics in extinction ratio, signal homogeneity, excess loss, and tolerance in the length of the splitter. 相似文献
62.
Spectral shape tunable band-rejection filter using a long-period fiber grating with divided coil heaters 总被引:2,自引:0,他引:2
Jun Kye Bae Sang Hyuck Kim Jun Hee Kim Jinho Bae Sang Bae Lee Je-Myung Jeong 《Photonics Technology Letters, IEEE》2003,15(3):407-409
We have developed a new type of tunable band rejection filter, which provides high spectral-shaping flexibility in a wide tuning range. The filter consists of a long-period fiber grating (LPFG) with divided coil heaters. Each of the divided coil heaters is controlled individually to adjust a temperature distribution along the LPFG and to modify the spectral shape of the LPFG filter. The tunable band rejection filter is demonstrated to function properly when applied as an erbium-doped fiber amplifier gain-flattening filter. 相似文献
63.
Man Chang Tae-Wook Kim Joonmyoung Lee Minseok Jo Seonghyun Kim Seungjae Jung Hyejung Choi Takhee Lee Hyunsang Hwang 《Microelectronic Engineering》2009,86(7-9):1804-1806
We investigated the impact of charge injection and metal gates (Al and Pt) on the data retention characteristics of metal–alumina–nitride–oxide–silicon (MANOS) devices for NAND flash memory application. Through the theoretical and experimental results, the highly injected charge (ΔVTH) could cause the band bending of Al2O3, which reduced the tunneling distance across Al2O3. Thus, the dominant charge loss path is not only toward SiO2 but also toward Al2O3 direction. Compared to low-metal work function (ФM), ONA stack with high-ФM showed better data retention characteristics, even if ΔVTH is high. This could be explained by Fermi level alignment for different ФM, which results in the reduction of electric field across the Al2O3 compensated by the ΔФM (ФPt ? ФAl). 相似文献
64.
Wonyoung Lee Hee Joon Jung Min Hwan Lee Young‐Beom Kim Joong Sun Park Robert Sinclair Fritz B. Prinz 《Advanced functional materials》2012,22(5):965-971
The role of grain boundaries on oxygen surface exchange in an oxide ion conductor is reported. Atomic‐scale characterization of the microstructure and chemical composition near the grain boundaries of gadolinia‐doped ceria (GDC) thin films show the segregation of dopants and oxygen vacancies along the grain boundaries using the energy dispersive spectroscopy in scanning transmission electron microscopy (STEM‐EDS). Kelvin probe microscopy is employed to verify the charge distribution near grain boundaries and shows that the grain boundary is positively charged, indicating a high concentration of oxygen vacancies. AC impedance spectroscopy on polycrystalline GDC membranes with thin interfacial layers with different grain boundary densities at the cathodes demonstrated that the cells with higher grain boundary density result in lower electrode impedance and higher exchange current density. These experimental evidences clearly show that grain boundaries on the surface provide preferential reaction sites for facilitated oxygen incorporation into the GDC electrolyte. 相似文献
65.
Min‐Soo Kang Bong‐Su Kim Kwang Seon Kim Woo‐Jin Byun Hyung Chul Park 《ETRI Journal》2012,34(5):649-654
This paper presents a novel 16‐quadrature‐amplitude‐modulation (QAM) E‐band communication system. The system can deliver 10 Gbps through eight channels with a bandwidth of 5 GHz (71‐76 GHz/81‐86 GHz). Each channel occupies 390 MHz and delivers 1.25 Gbps using a 16‐QAM. Thus, this system can achieve a bandwidth efficiency of 3.2 bit/s/Hz. To implement the system, a driver amplifier and an RF up‐/down‐conversion mixer are implemented using a 0.1 µm gallium arsenide pseudomorphic high‐electron‐mobility transistor (GaAs pHEMT) process. A single‐IF architecture is chosen for the RF receiver. In the digital modem, 24 square root raised cosine filters and four (255, 239) Reed‐Solomon forward error correction codecs are used in parallel. The modem can compensate for a carrier‐frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of 10?5 at a signal‐to‐noise ratio of about 21.5 dB. 相似文献
66.
Wireless Networks - Spatial and temporal correlation between sensor observations in an Internet of Things environment can be exploited to eliminate unnecessary transmissions. Transmitting less data... 相似文献
67.
Self‐Interference Cancellation for Shared Band Transmission in Nonlinear Satellite Communication Channels 下载免费PDF全文
For efficient spectral utilization of satellite channels, a shared band transmission technique is introduced in this paper. A satellite transmits multiple received signals from a gateway and terminal in the common frequency band by superimposing the signals. To improve the power efficiency as well as the spectral efficiency, a travelling wave tube amplifier in the satellite should operate near the saturation level. This causes a nonlinear distortion of the superimposed transmit signal. Without mitigating this nonlinear effect, the self‐interference cannot be properly cancelled and the desired signal cannot be demodulated. Therefore, an adaptive compensation scheme for nonlinearity is herein proposed with the proper operation scenario. It is shown through simulations that the proposed shared band transmission approach with nonlinear compensation and self‐interference cancellation can achieve an acceptable system performance in nonlinear satellite channels. 相似文献
68.
Jeong-Won Yoon Bo-In Noh Young-Ho Lee Hyo-Soo Lee Seung-Boo Jung 《Microelectronics Reliability》2008,48(11-12):1864-1874
This study examined the effects of isothermal aging and temperature–humidity (TH) treatment of substrate on the joint reliability of a Sn–3.0Ag–0.5Cu (wt.%)/organic solderability preservative (OSP)-finished Cu solder joint. Two types of OSP-finished chip-scale-package (CSP) substrates were used, those subjected and not subjected to the TH test. This study revealed an association between the interfacial reaction behaviors, void formation and mechanical reliability of the solder joint. Many voids were formed at the interface of the OSP-finished Cu joint subjected to the TH test. These voids were caused by the oxidation of the OSP-finished Cu substrate during the TH test. In the shear tests, the shear force of the joint with the substrate not subjected to the TH test was slightly higher than that with the TH test. The mechanical reliability of the solder joint was degraded by voids at the interface. 相似文献
69.
Tran Thanh Tung Mickael Castro Jean-Francois Feller Tae Young Kim Kwang S. Suh 《Organic Electronics》2013,14(11):2789-2794
A hybrid of graphene and conducting polymer holds great potential as the active materials for high performance chemical sensor application. In this work, a thin hybrid film of reduced graphene oxide (RG-O) and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated by means of vapor phase polymerization and explored as active material for chemical sensors. The chemical sensors based on hybrid film of RG-O and PEDOT are capable of detecting electrical signals caused by the absorption of trace levels of different analyte vapors with high sensitivity, selectivity and fast response. 相似文献
70.
This paper describes an ultra‐wideband (UWB) antenna that uses a ring resonator concept. The proposed antenna can operate in the entire UWB, and the IEEE 802.11a frequency band can be rejected by inserting a notch stub into the ring resonator. The experiment results indicate that the measured impedance bandwidth of the proposed antenna is 17.5 GHz (2.5 GHz to at least 20 GHz). The proposed UWB antenna has omnidirectional radiation patterns with a gain variation of 3 dBi (1 dBi to 4 dBi). 相似文献