排序方式: 共有59条查询结果,搜索用时 15 毫秒
31.
提出了一种低浓度重金属离子溶液的快速富集净化处理方法。目标金属离子首先络合为负离子,在正电压牵引下,金属络合离子到达离子膜表面,在膜表面阴离子层吸引下通过阳离子交换膜,并在受体溶液中再次络合为阴离子络合物,在电场作用下向阳极区移动。富集电流为1.5mA,汞离子、镉离子的富集时间分别为20,60min,水样中汞离子、镉离子的富集倍数分别为10.5,3.2倍。本方法避免了液膜稳定性缺陷。 相似文献
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An electroabsorption modulator using the intrastep quantum well (IQW) active region is fabricated for optical network systems. The strain-compensated InGaAsP/InGaAsP IQW shows good material quality and improved modulation properties, high extinction ratio efficiency IOdB/V and low capacitance (〈 0.42 pF), with which an ultra high frequency (〉 15 GHz) can be obtained. High-speed measurement under high-power excitation shows no power saturation up to excitation power of 21 dBm. To our knowledge, the input optical power is the highest reported for multi-quantum well EAMs without heat sinks. 相似文献
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High-strained InGaAs/InGaAsP multiple quantum wells (MQWs) distributed feedback (DFB) lasers, fabricated using metal organic chemical vapor deposition, are presented at 1.82 μm with a high side-mode-suppression ratio of 49.53 dB. The current- and temperature-tuning rates of the DFB mode wavelength are 0.01 nm/mA and 0.13 nm/℃, respectively. A characteristic temperature of 51 K is also confirmed. The DFB laser demonstrates good performance and can be applied to H2 O concentration sensing. 相似文献
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A GaAs based high power distributed feedback (DFB) semiconductor laser with a second-order grating has been demonstrated. An output power of 150row at an injection current of 350mA is realized with a 1-mm cavity length. With a new design of the waveguide structure, the DFB laser maintains a stable single longitudinal mode around 106Ohm with a side mode suppression ratio of larger than 50dB. 相似文献
37.
A 10-GHz Bandwidth Electroabsorption Modulated Laser by Ultra-Low-Pressure Selective Area Growth
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A novel integration technique has been developed using band-gap energy control of InGaAsP/InGaAsP multiquantum-well (MQW) structures during simultaneous ultra-low-pressure (22 mbar) selective-area-growth (SAG) process in metal-organic chemical vapour deposition. A fundamental study of the controllability of band gap energy by the SAG method is performed. A large band-gap photoluminescence wavelength shift of 83nm is obtained with a small mask width variation (0-30μm). The method is then applied to fabricate an MQW distributed-feedback laser monolithically integrated with an electroabsorption modulator. The experimental results exhibit superior device characteristics with low threshold of 19mA, over 24 dB extinction ratio when coupled into a single mode fibre. More than 10 GHz modulation bandwidth is also achieved, which demonstrates that the ultra-low-pressure SAG technique is a promising approach for high-speed transmission photonic integrated circuits. 相似文献
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评定微波消解电感耦合等离子体质谱(ICP-MS)法测定大米中镉含量的不确定度。该法测量不确定度主要来源于标准曲线拟合、标准工作溶液配制和测量重复性。结果表明,微波消解ICP-MS法测定大米中镉质量分数为0.174 mg/kg时,在95%置信水平下,其扩展不确定度为0.021 mg/kg,包含因子k=2。通过对各不确定度分量的计算和评定结果量值比对,得出测量过程中不确定度的主要来源是标准曲线拟合,其次为系列标准工作溶液的配制和测量重复性,贡献值分别为70.9%、11.2%和11.8%,样品称量和定容过程中量器以及实验室温度变化引入的不确定度较小。 相似文献
39.
Design and Characterization of Evanescently Coupled Uni-Traveling Carrier Photodiodes with a Multimode Diluted Waveguide Structure
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A new evanescently coupled uni-traveling carrier photodiode (EC-UTC-PD) is designed, fabricated and characterized, which incorporates a multimode diluted waveguide structure and UTC active waveguide structure together. A high responsivity of 0.68 A/W at 1.55-μm without an anti-reflection coating, a linear photocurrent responsivity of more than 21 mA, and a large -1 dB vertical alignment tolerance of 2.5 μm are achieved. 相似文献
40.
We fabricate 1.5 μm InGaAsP/InP tunnel injection multiple?quantum-well (TI-MQW) Fabry-Perot (F-P) ridge lasers. The laser heterostructures, including an inner cladding layer and an InP tunnel barrier layer, are grown by metal-organic chemical-vapor deposition (MOCVD). Characteristic temperature T0 of 160 K at 20°C is obtained for 500?μm?long lasers. T0 is measured as high as 88 K in the temperature range of 15?75°C. Cavity length dependence of T0 is investigated. 相似文献