Xiaoxiao Jiang

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.

Plasmon-enhanced sensing: current status and prospects

By combining different plasmonic nanostructures with conventional sensing configurations, chemical/biosensors with significantly enhanced device performance can be achieved. The fast development of plasmon-assisted devices benefits from the advance of nanofabrication technology. In this review, we first briefly show the experimental configurations for testing plasmon enhanced sensing signals and then summarize the classic nanogeometries which are extensively used in sensing applications. By design, dramatic increment of optical signals can be obtained and further applied to gas, refractive index and liquid sensing.

Maskless fabrication of slanted annular aperture arrays

We report maskless fabrication of high-aspect-ratio slanted annular aperture arrays (SAAAs) in gold films using focused ion beam lithography. By tilting the substrate, SAAAs with the desired tilting angle can be fabricated. Our experimental results demonstrate accurate control over aperture size, obliqueness, and reproducibility. We also show that the resulted plasmonic resonances of SAAAs can be effectively tuned via obliqueness control. This versatile approach may enable fabrication of more complicated plasmonic nanostructures. The demonstrated gold SAAAs could also find many potential applications in plasmon-assisted sensing and surface enhanced spectroscopy.

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.