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排序方式: 共有1502条查询结果,搜索用时 31 毫秒
121.
We design and fabricate ultra-high-quality (Q) photonic nanocavities in a symmetrically glass-clad silicon (Si) two-dimensional (2D) photonic crystal (PhC) structure. We theoretically investigate the dependence of the refractive index of the glass on the Q factors for asymmetric and symmetric structures. We show that the index-symmetric distribution of the glass is a critical factor to realize ultrahigh Q factors for glass-clad 2D PhC structures. We fabricate symmetrically glass-clad Si PhC nanocavities and achieve a record Q factor of 1×10(6), comparable with the highest Q factors of nanocavities in air-bridge structures. 相似文献
122.
Young-Deuk Jeon Seung-Hoon Lee 《Electronics letters》1999,35(23):1990-1991
Acquisition time minimisation techniques using a two-stage amplifier for high-speed analogue signal processing in mixed-mode circuits are presented. The proposed techniques reduce overshoots and undershoots of the amplifier by adjusting its transconductance and achieve high-speed performance with little modification to the conventional amplifier architecture. The measured signal-to-noise-and-distortion ratio of the prototype 12 bit CMOS ADC based on the proposed techniques is improved by >5 dB at a 50 MHz sampling clock 相似文献
123.
12 nm tunable WDM source using an integrated laser array 总被引:1,自引:0,他引:1
Pezeshki B. Mathur A. Zou S. Jeon H.-S. Agrawal V. Lang R.L. 《Electronics letters》2000,36(9):788-789
A 12 nm tunable source with up to 15 mW fibre coupled power has been fabricated by integrating four DFB lasers and a booster amplifier to provide a single output. High-yield and low-cost techniques are used, such as quarter-wave-shifted phase-masks for wavelength definition and an integration technique with only two regrowths 相似文献
124.
125.
Jong Hyeuk Lim Kyong Nam Kim Min Hwan Jeon Jong Tae Lim Geun Young Yeom 《Plasma Chemistry and Plasma Processing》2011,31(3):507-515
Electrical and plasma properties of a U-shaped internal inductively coupled plasma (ICP) source with/without a Ni-Zn ferrite
module installed above the ICP antenna were investigated. By installing the ferrite module on the antenna, the increase of
plasma density and the decrease of plasma potential could be observed. The increase of plasma density was related to the efficient
inductive coupling to the plasma by concentrating the induced magnetic field between the antenna and the substrate. At 800 W
of ICP power and 20mTorr Ar, a high density plasma on the order of 4.5′1011/cm3 could be obtained. 相似文献
126.
Dr. Sung Lan Jeon Dr. Min Kyung Chae Eun Ju Jang Dr. Chulhyun Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(13):4217-4222
Iron oxide nanoparticles as contrast agents are reported to effectively improve magnetic resonance imaging of tissues and cells. In this work, cleaved iron oxide nanoparticles (CIONPs) were generated from hydrophobic FeO nanoparticles (HIONPs) by coating their surfaces with PEG‐phospholipids, oxidizing them under water, and slowly removing the residual FeO phase in phthalate buffer. The synthesized CIONPs showed good r2 values of up to 258 s?1 mM ?1. Thus, the CIONPs can be employed as vectors for drug delivery due to their unique structure with an empty inner space, which enables their use in a wide range of applications. 相似文献
127.
128.
Min-Yong Jeon Hak Kyu Lee Joon Tae Ahn Dong Sung Lim Do Il Chang Kyong Hon Kim Seung Beom Kang 《Electronics letters》2000,36(4):300-302
An electronically wavelength tunable modelocked fibre laser operating over a 50 nm range using an all-fibre acousto-optic tunable filter is presented. The tuning range is 1557-1607 nm, for a 70 m long erbium-doped fibre (EDF) with a 270 ppm concentration 相似文献
129.
Jae Seung Yun Hang Suk Noh Soon Ick Jeon Chang Ju Kim 《Electronics letters》2003,39(17):1228-1230
A TX/RX dual microstrip 8/spl times/4 array antenna for satellite communication is designed, fabricated and measured and its element characteristics are analysed using finite difference time domain (FDTD) method. TX/RX frequency ranges are 14.0-14.5 GHz, 11.7-12.75 GHz, respectively, and vertical and horizontal polarisations are used for TX and RX. This antenna uses microstrip direct feeding for RX and aperture coupled stripline feeding for TX and accommodates stacked elements for a high directivity and wide impedance bandwidth. FDTD gives more accurate results because of the consideration of finite structure and two imperfect ground planes. This element has a return loss below -8 and -14 dB over the TX and RX frequency ranges and a gain of 7.5 and 8.3 dBi at the centre frequency of TX and RX. Return loss below -10 and -14 dB and a gain of 21.4 and 20.0 dBi were achieved for the TX and RX array, respectively. 相似文献
130.
Yoon‐Jae So Hyoung‐Goo Jeon Young‐Hwan You Myung‐Sun Baek Hyoung‐Kyu Song 《ETRI Journal》2004,26(5):397-404
In this paper, we provide a new detection scheme for a pilot symbol assisted interference nulling and cancellation operation to reduce unexpected effects owing to parallel transmission in orthogonal frequency division multiplexing (OFDM)‐based spatial multiplexing systems. We have shown that the investigated OFDM vertical Bell laboratories layered space time (VBLAST) detection based on hybrid processing performs better than ordinary OFDM‐VBLAST detections based on serial processing and parallel processing, respectively. 相似文献