Jiulin Shi

Experimental investigation on the competition between wideband stimulated Brillouin scattering and forward stimulated Raman scattering in water

The utilization of a simple focused optical cell to bring to light the competition between wideband stimulated Brillouin scattering (WSBS) and forward stimulated Raman scattering (FSRS) is investigated experimentally. A pulsed, wide bandwidth second-harmonic Nd:YAG laser is used as the pump source. We found that, the competition between WSBS and FSRS is an alternate process, which one dominated depends on the linewidth and energy of the pump laser, focal length, and optical breakdown.

Investigation of the influence of temperature on threshold value and pulse duration of stimulated Brillouin scattering in liquid water

The threshold value and pulse duration of stimulated Brillouin scattering (SBS) have been measured over the temperature range 10–45°C in liquid water. Also, a theoretical analysis based on the temperature dependence of SBS has been carried out. The results show that the threshold value of SBS decreases with an increase of temperature, whereas the measured pulse duration increases with an increase of temperature.

Stimulated Brillouin scattering in combination with visible absorption spectroscopy for authentication of vegetable oils and detection of olive oil adulteration

Vegetable oils provide high nutritional value in the human diet. Specifically, extra virgin olive oil (EVOO) possesses a higher price than that of other vegetable oils. Adulteration of pure EVOO with other types of vegetable oils has attracted increasing attentions. In this work, a stimulated Brillouin scattering (SBS) combined with visible absorption spectroscopy method is proposed for authentication of vegetable oils and detection of olive oil adulteration. The results provided here have demonstrated that the different vegetable oils and adulteration oils exhibit significant differences in normalized absorbance values of two relevant wavelengths (455 and 670 nm) and frequency shifts of SBS. The normalized absorbance values of all spectra at the two relevant wavelengths of 670 nm and 455 nm linearly decrease with the increase of the adulteration concentration. The Brillouin frequency shifts exponentially increase with the increase of the adulteration concentration. Due to non-destructive and requiring no sample pretreatment procedure, this method can be effectively employed for authentication and detection of oils adulteration.

Use of the fluorescence of rhodamine B for the pH sensing of a glycine solution

The fluorescence of rhodamine B can be strongly affected by its environmental pH value. By directly introducing the dye into various glycine solution, the fluorescence was used to monitor the pH value in the range of 5.9 ~ 6.7. Two newly developed techniques for broadband analysis, the barycenter technique and the self-referenced intensity ratio technique, were employed to retrieve the pH sensing functions. While compared with traditional techniques, e.g. the peak shift monitoring, both the two new techniques presented finer precision. The obtained sensing functions may find their applications in the test of biochemical samples, body tissue fluid, water quality, etc.

Laser pulse compression method to measure Brillouin gain in water

We present a method by which to determine the gain coefficient of stimulated Brillouin scattering (SBS) in water from the pulse compression ratio of the pump pulse duration to the output Stokes pulse duration. To achieve this objective, we have measured the pulse duration of SBS over the temperature range of 5–40 °C. The gain coefficient of SBS has been calculated using the measured pulse compression ratio, the pump intensity, and the characteristic length. Also, in this article, we derive the theoretical model based on coupled wave equations and we demonstrate the method at lower pump energies which is an effective approach for measuring the gain coefficient of SBS.

Fabrication of 1×4 MMI Coupler with DMD System Based on Holography

This article presents a new method to make MMI coupler on the Silver Halide Film with Digital Micro mirror Device (DMD) system, without using special mask plate. It uses the refractive index modulation capacity of Silver Halide Film by controlling the exposure to make different refractive indexes thereby forms the core and cover. It does not need further etching and just one exposure, which provides a fast and low-cost method to make holographic micro-optical components.