Photonic crystal slotted slab waveguides

We report on the fabrication of photonic crystal waveguides in SOI that comprise an air-slot in the centre. The slot serves to confine suitably polarised optical radiation (H-polarisation) and due to its small size, provides extremely high field intensity values out with the high index material. Adding the photonic crystal environment then provides full control over the dispersive properties of this waveguide. We demonstrate the successful operation of this structure experimentally and explain its key features.     

缝管增强火焰原子吸收分析灵敏度的研究—铅的测定

近年来,人们为了提高火焰原子吸收光谱分析的灵敏度,采用了一些新技术.Watling首先提出使用开缝石英管提高火焰原子吸收法测定某些元素的分析灵敏度和准确度。之后,缝式石英管火焰原子吸收技术在实际工作中得到了应用和发展.最近,刘永铭等考察了管性能的影响,指出该技术的可行性。一般认为缝管火焰原子吸收法提     

Sensitivity Enhancement for Slotted Quartz Tube Flame Atomic Absorption Spectrometry Using a Gas Screen

Slotted Quartz Tube (SQT) is a simple device that provides a sensitivity enhancement of 2–5 times in Flame Atomic Absorption Spectrometry (FAAS) depending on the element. A Gas Screen-Slotted Quartz Tube (GS-SQT) was designed to further increase sensitivity. For this purpose, two slotted gas chambers were fixed on the left and right sides of a burner head and Ar gas was supplied into these chambers perpendicular to the light path to produce two thin layers of gas screen. It was observed that these Ar screens can move up the flame tails in two ends of SQT. In addition to an increase in sensitivity by the use of SQT, Ar screen resulted in a further improvement in characteristic concentrations, C₀, by a factor of 1.60 for Cd, 2.01 for Co, 1.42 for Cu, 1.94 for Mn, 1.86 for Ni, 1.78 for Pb, 1.62 for Se, and 1.09 for Zn. In addition to the enhancement in sensitivity, gas screen also helps by protecting the spectrometer from the adverse effect of using slotted quartz tube. The system is very simple and low-cost; it can be produced and applied easily.     

Characterization of a tunable three-section slotted Fabry-Perot laser for advanced modulation format optical transmission

In this paper we report on the characterization of a narrow linewidth three-section tunable slotted Fabry-Perot laser. The SMSR of the 25 available 100-GHz ITU channels is above 30 dB, whereas their average linewidth is 538 kHz with a maximum below 800 kHz. The RIN spectra of six different channels are also measured and a maximum average RIN of −135 dB/Hz is obtained. The linewidth effect of the laser in a 1.25 Gb/s DPSK transmission system is investigated by comparing the performance between the slotted Fabry-Perot laser and a commercial SG-DBR laser respectively. Error free transmission of the slotted Fabry-Perot laser shows the benefit of the narrow linewidth of the device for systems employing advanced modulation formats.     

Performance of slotted pores in particle manufacture using rotating membrane emulsification

This paper addresses the use of different slotted pores in rotating membrane emulsification technology. Pores of square and rectangular shapes were studied to understand the effect of aspect ratio （1-3.5） and their orientation on oil droplet formation. Increasing the membrane rotation speed decreased the droplet size, and the oil droplets produced were more uniform using slotted pores as compared to circular geometry. At a given rotation speed, the droplet size was mainly determined by the pore size and the fluid velocity of oil through the pore （pore fluid velocity）. The ratio of droplet diameter to the equivalent diameter of the slotted pore increased with the pore fluid velocity. At a given pore fluid velocity and rotation speed, pore orientation significantly influences the droplet formation rate： horizontally disposed pores （with their longer side perpendicular to the membrane axis） generate droplets at double the rate of vertically disposed pores. This work indicates practical benefits in the use of slotted membranes over conventional methods.     

单缝石英管火焰原子吸收法测定大米中微量铜

本文根据文献报道使用单缝石英管火焰原子吸收法提高火焰原子法的灵敏度,对大米中微量铜的测定进行研究。方法简单、快速,文献尚未见报道。由实验得到了比较满意的分析结果,回收率为96～102%。变异系数为1.9%,灵敏度可提高3倍。     

缝管原子捕集初探

本文针对九种元素初步探索了缝管捕集原子吸收的各种参数影响,给出缝管捕集法与常规火焰法的灵敏度、精密度对比结果。并进行了单缝管、双缝管及微量进样的比较实验。该法用于测定自来水和啤酒样品中的Cd、Cu、Pb、Zn,取得结果较为满意。     

Liquid refractive index sensor based on slow light in slotted photonic crystal waveguide

A high sensitive and compact refractive index sensor based on slotted photonic crystal waveguide (S-PhCW) is demonstrated. This design is worked on a Mach–Zehnder interferometer (MZI) configuration with S-PhCW as the measuring arm, which can be used to detect any changes in refractive index that correspond to different concentration of the measuring liquid. Combining the slow light enhancement in photonic crystal waveguide (PhCW) with the advantage of excellent optical confinement in slot waveguide, the sensitivity of this simple scheme can reach to 2.3 × 10⁹ nm/RIU with the active region of only 1 mm long.     

开缝石英管原子化技术的改进

近年来,为提高火焰原子吸收光谱法的灵敏度,先后研究过水冷石英管和开缝石英管(简称缝管)原子化技术.前者使灵敏度提高1～2个数量级^[1～3],后者只提高几倍^[4～6].缝管技术比水冷石英管技术的装置简单,操作方便快速,但因其灵敏度不高,应用受到限制.本文以镉为例,探讨了提高缝管技术灵敏度的途径.     

A model for the scattering of long waves by slotted breakwaters in the presence of currents

Slotted breakwaters have been used to provide economical protection from waves in harbors where surface waves and currents may co-exist. In this paper, the effects of currents on the wave scattering by slotted breakwaters are investigated by using a simple model. The model is based on a long wave approximation. The effects of wave height, barrier geometry and current strength on the reflection and transmission coefficients are examined by the model. The model results are compared with recent experimental data. It is found that both the wave-following and wave-opposing currents can increase the reflection coefficient and reduce the transmission coefficient. The model can be used to study the interaction between long waves and slotted breakwaters in coastal waters. The project partially supported by the Hong Kong Research Grant Council under Grant No. HKUST-DAG03/04.EG39 and HKUST6227/04E.