Qiongchan Gu

Fabrication and characterization of well-aligned plasmonic nanopillars with ultrasmall separations

We show the fabrication of well-aligned gold and silver nanopillars with various array parameters via interference lithography followed by ion beam milling and compare the etching rates of these two metallic materials. Silver is suitable for fabricating ultrafine arrays with ultrasmall separations due to high milling rates. The optical properties of the fabricated nanopillars are specifically characterized from both normal incidence and oblique incident angles. Tunable surface plasmon resonances are achieved with varying structural parameters. Strong coupling effects are enabled when the separation between adjacent nanopillars is dramatically reduced, leading to useful applications in sensing and waveguiding.

A CO detection system based on double fiber bragg gratings

CO is the main component of mine gas. It is flammable and explosive. It is very important to realize the real-time detection of CO gas. It concentrates to the safety of mining industry and personal safety. In this paper, a double optical fiber sensing system based on a set of differential absorption technique is designed according to the CO molecular spectral absorption characteristics. The light source is LED. Reentrant type absorption cell is used as the gas chamber. The wavelength modulation and narrow beam are obtained by the fiber grating and photoelectric diode. The differential absorption detection is realized by the application of fiber Bragg grating narrowband filter characteristics and the double optical path. It is shown by the experiment that the system has high feasibility and reliability. The high sensitive detection of CO gas can be readily achieved.

The Type Detection of Mineral Oil Fluorescence Spectroscopy in Water Based on the KPCA and CCA-SVM

The composition of the mineral oil is complex. Especially mineral oil of 3D fluorescence spectra data dimension higher, more complex processing. In this paper, The method of kernel principal component analysis plus canonical correlation analysis (CCA) is used to do classify the spectroscopy data processed by the KPCA. Kernel method is used within principal component analysis, since CCA uses all the kernel principal component of the converted samples from KPCA, no discrimination is lost in the analysis.The experiment results show that it is effective to extract the main feature of the spectroscopy. The identification of the oils can be realized with high discrimination which is 94.11%.

Shaping the profile of photonic crystal nanorods

The focused ion beam technique is a frequently used method to manufacture photonic crystal structures due to its capability of defining patterns in a wide range of materials without using masks. One critical drawback of FIB milling technique is the non-vertical profile resulted from redeposition effects during lithography. Tapered sidewalls may impact the performance of the fabricated device significantly. In a previous work, we have shown it is possible to shape the profile of nanoholes by truncating the seriously tapered bottoms. Here, we report on the re-definition of nanorod photonic crystals using focused ion beam milling. The proposed method is simple and entirely monolithic.

Fabrication of nanoarms and nanotips via focused ion beam milling

Patterning with ion beams at the nanometer scale has found various important applications in optoelectronics and nanofabrication. During the process of focused ion beam milling, many different effects occur simultaneously, including sputtering, material redeposition, and implantation. Based on the powerful and versatile capability of the focused ion beam technique, we propose a novel method to fabricate nanoarms and nanotips in this work. Using a complex milling process, we show it is possible to manufacture nanoarms in metallic materials by etching the sample at different angles. We also demonstrate the fabrication of nanotips with tapered and uniform profiles, respectively. Our approach may open new opportunities for ion-beam based fabrication of a wide range of optical and electronic nanodevices.

Light through nanocrescent arrays

In this work, we show the fabrication of nanocrescent arrays with different sizes. We also investigate the optical response of such nanocrescent arrays and perform theoretical calculations. Our approach may find extensive applications in nanophotonics and integrated optics.

Controlling light through double-ring arrays

Coaxial structures are extremely crucial for investigations on surface plasmons since they exhibit special optical properties compared with apertures with other shapes. Different from the traditional extraordinary optical transmission (EOT) observed from nanohole arrays, these ring-like structures can excite cylindrical surface plasmon and planar surface plasmon simultaneously. The nanoring cavities can act as Fabry-Pérot resonators, giving rise to coupling between different modes. Importantly, these nanorings have found promising applications in fabricating color filters. Moreover, these coaxial structures are compatible with liquid crystal display techniques, leading to actively tunable optical devices which may be broadly applied in nanophotonics and integrated optics.

The fiber-optic sensing fluorescence detection system for Chinese traditional medicine injection based on charge-coupled devices

A method for the detection of Chinese traditional medicine injection concentration is designed which is based on the fiber transducer technology and the fluorescence analyzing technology. It adopts a sphere fiber-optics probe to realize the highly active caption and transmission of the fluorescence signal. The charge-coupled devices(CCD) is used to realize the high efficiency detection of the fluorescence spectrum. The fluorescence is highly active light spitted by the function of the spatial dispersion and plane focusing of the concave grating and the optoelectronic conversion of the CCD. It formatted the spectrum on the focal plane of the CCD. The spectrum is converted to the electric pressure signal by the CCD detection. The experiment indicates that the system has a minimum detecting limit of the density is 0.04ppm.The partial least squares (PLS) is used to get the the linear regression of the samples. The value of the RMSEP is 0.1631.