Yury Zimin

NIR Spectrum Analysis of Natural Gas Based on Hollow-Core Photonic Bandgap Fiber

In this paper, we present a quantitative near-infrared spectroscopy measurement of the chemical compositions of gas mixtures, such as natural gas, based on a photonic bandgap fiber gas cell. The absorption spectra of the methane and ethane gases were investigated in the near-infrared region. The absorption lines of the ethane gas were observed in the 1600-1616-nm region, and were totally different from those of the methane gas. To our knowledge, this is the first study to measure the individual absorption lines of ethane in this range of wavelengths, and our finding has a great potential for sensing highly sensitive gases.

U-Band Wavelength References Based on Photonic Bandgap Fiber Technology

In this paper, we surveyed potential wavelength references in U-band wavelength region. The hollow-core photonic bandgap fiber (PBGF) filled with methane (CH4) gas is used as a gas cell. The experimental results clearly indicate that the weak absorption lines of methane can be used as U-band wavelength division multiplexing (WDM) channel references due to the long interaction path length provided by PBGF. The absorption lines of CH4 are useful as wavelength references in the 1625-1700 nm region. In addition, we have measured the pressure broadening and the wavelength stability of absorption lines, and find that absorption lines are particularly insensitive to external perturbation. This technique is useful for wavelength calibration of components of communication system, or as monitor the wavelength of the channels. It may be implemented in next-generation WDM communication systems.

Low-temperature anodic bonding of silicon and crystal quartz wafers for MEMS application

Conventional fabrication of MEMS devices based on the quartz consists of a high tech processing of the very crystal with electrodes and subsequent manual assembling to the package. The limitation of the manual assembling could be eliminated through integration of the processing and packaging in a single high-tech process by means of silicon/crystal quartz bonding. New integrated technology would be able to create devices with new capabilities unobtainable with outdated technology. Low temperature anodic bonding of silicon and quartz wafer appears to be the most promising method for elaboration of the unified technology. In this work, strong bonding of Siand crystal quartz wafers close to the mechanical strength of the initial materials has been achieved as result of low-temperature annealing in electric field under pre-activation of crystal surfaces by oxygen plasma. Tensile test shows a disruptive stress of the samples at about 35 MPa. High bonding strength is associated with electric field applied during the annealing process. Similar bonding strength has been achieved for a pair of crystal quartz and structured silicon wafer with pre etched micro cavities. Strong low-temperature bonding, including the bonding with pre-etched cavities, could be a key element of new technology of MEMS devices and provide new opportunities for miniaturization of sensors based on crystal quartz.

Multi-spectral Analytical Systems Using LIBS and LII Techniques

In this paper, we propose an advanced approach to particle analysis, involving laser-induced breakdown spectroscopy (LIBS) and laser-induced incandescence (LII) temporal analytical techniques. Various technical properties of fine particles are analyzed via LIBS and LII. LIBS is a useful tool for determining the elemental composition and relative concentration of various materials, whereas LII facilitates the measurement of particle size. Both techniques do not require any pre-processing. The combined use of the LIBS and LII techniques enables highly synergistic fine particle measurement. In the LIBS section, we propose spectrometric analysis via a novel ink-jet technique, and we discuss the effectiveness of Ar as a surrounding gas. In the LII section, we compare the calculated particle size prediction with the experimental results.

Development of sensing system for carbonaceous particles using LIBS combined with LII temporal analytical technique

This report describes a new sensing system for carbonaceous particles detection using combination with two techniques of laser-induced breakdown spectroscopy (LIBS) and laser-induced incandescence (LII). Our research group has improved LIBS system applied for quantitative analysis. Although the basic principal of the LIBS quantitative measurements were well understood, several uncertainties still remained for complete description especially for the particle size measurement. Elemental composition and density of the particle were determined by using LIBS. Particle size measurement was accomplished with the help of LII. On the presented system, only controlling the power density of the light source allowed to switch from LIBS to LII.

Photonic Bandgap Fibre Based Gas Sensing: Current Status and Future Possibilities

A development of gas concentration sensing systems based on a photonic bandgap fiber (PBGF) is described. Several types of PBG fibers of various parameters and core diameters ranging from 10.9 to 26.25 microns have been designed and tested. The capillary gas flow rate within the fiber has been simulated and measured. A new method for cutting the fiber using focused ion beam in a vacuumed chamber for fine milling was tested to obtain the required angle of the fiber’s end, to avoid the destruction of the cladding structure and to create a novel low-loss splice for use between PBGF and the conventional solid-core fiber. The measurement results obtained using proposed systems for selected types of gases are presented. The experimental results clearly indicated a high overlap between the propagating light and filled gas inside the PBGF. Therefore, these studies can contribute to highly sensitive gas sensing, higher accuracy of wavelength references, and other applications.

Development of a 3D laser scanning system for laser-induced breakdown spectroscopy

We report a new laser scanning device to be used in a laser-induced breakdown spectroscopy (LIBS) system. The system consists of a tunable lens, a cold mirror that transmits infrared wavelengths, two galvano mirrors, a condenser lens, and an optical axis adjusting laser. Conventional laser scanning technologies have two main applications: (i) in the industry, for drawing simple dots/lines with high power lasers; and (ii) in laser art projections, where far more complex illustrations and animations using visible lasers have been achieved. These two applications have been developed separately. Our scanning system combines the advantages of both these technologies by employing high-strength galvano mirrors as well as a driving system that meets the international laser display association (ILDA) standard. Moreover, by assembling the electrically controlled tunable lens, any measuring point where the generation of laser-induced plasma is needed, can be reached in a given space.

A reliability of silicon-crystalline quartz bonding through reducing of the residual stresses

In this work, a new additional opportunity to reduce the residual stresses when bonding a pair of dissimilar materials such as silicon and crystalline quartz has been revealed as a result of theoretical calculations. In parallel with a traditional method, based on lowering of bonding temperature, additional reduction of the residual stresses becomes possible owing to difference in elastic properties of dissimilar materials of the pair. In the case of coupled plates, with different coefficients of thermal expansion, the residual stresses can be reduced if the following two conditions hold simultaneously: E<inf>1</inf>/(1−v<inf>1</inf>)&#60; E<inf>2</inf>/(1−v<inf>2</inf>) and h<inf>1</inf>&#60;h<inf>2</inf>. Here E<inf>i</inf>- the Youngs modulus, v<inf>i</inf>- the Poisson ratio, and hi- the thickness of the first (i=1) and the second (i=2) bonded plates respectively. For the quartz/silicon pair, the residual stresses at the interface will be approximately 20% lower if h<inf>1</inf>/h<inf>2</inf> =0.2 as compared the case when both wafers are of equal in thickness.

Ultratrace measurement using micro-droplet with gas-flow assistance in laser-induced breakdown spectroscopy

A new setup for laser-induced breakdown spectroscopy (LIBS) is introduced. This setup was designed for high sensitive quantitative analysis using the ink-jet technology and gas-flow assistance. The setup presented here allowed precise detection of a micro-droplet for guiding it into a laser beam spot area. The micro-droplet ejection system created constant volume of sample liquid and taking advantage of liquid physical state; density of the solution can be controlled accurately. That means the constant amount of media was maintained in a micro-droplet. This sampling system allowed generating small droplet (diameter 30 mum) confining the whole fixed volume of the sample material in the laser beam spot area (minimum beam spot diameter 53.2 mum), under the effects of any ambient gas. In this paper, the stability with practical use and improvement of detection limit for LIBS measurement is reported.