We demonstrate the fabrication of a white light blinded IR photo-detector sing a Si based metal insulator semiconductor (MIS) structure with multi-layers of SiO2/TiO2 dielectric and its characteristics of photo -responsivity. Spectral responsivity peak at 850 nm with high discrimination in visible light had been achieved in a MIS photo -detector with multiple layers of SiO2/TiO2 dielectrics. Reflection spectral measurements and I -V characteristics of the SiO2/TiO2 multi-layers with various layer number and thickness were used to explore the photo -detection in this MIS device structure. We found that high spectral discrimination of visible light of this multi-dielectric layers MIS device is due to the optical filtering property by these multi -layers and the mid-band gap impurity states existed at the interface between the Si substrate and these dielectric layers.
We demonstrate an application of fiber Bragg grating to measure the index of refraction of an unknown liquid by using a cladding depleted FBG. The measurements of the index of refraction were calibrated by the index oil with known index of refraction. Samples of liquid with difference percentage of sugar content were prepared and measured the index of refraction using this method. It shows that accuracy of index of refraction measurement as high as 0.01 can be achieved.
We present the study of the output characteristics of a distributed Bragg grating fiber ring laser (DBGFL) with different
coupling configuration with the fiber Bragg grating (FBG). The fiber ring laser was pumped by a 980 nm laser diode
with pig tail fiber connection with a 980/1550 WDM, and the resonator is contained in a fiber Bragg grating loop. Two
coupling configuration of the FBG have been used to study the effect to the output characteristics of the fiber ring laser.
It shows about the same output efficiency between the fiber ring laser with only reflection coupling and with reflection
/transmission coupling. In addition, a numerical model of calculating the multiple reflection/transmission feedback
coupling of the FBG has been proposed, and explains reasonably the experimental results.
We demonstrate the pulse laser deposition (PLD) of zirconium tin titanium oxide (Zr0.8,Sn0.2)TiO4 (ZST) thin film on
p-type Si (100)substrate by KrF excimer laser at room temperature, and the study of the effects of post-annealing to the
optical and dielectric properties of the deposited ZST thin films. Deposition rate of ZST thin film at 0.3 Angstrom/pulse has been
achieved with laser fluences of 1500 mJ/cm2. Raman spectroscopy, X-ray diffraction (XRD), and scanning electron
microscopy (SEM) are used to study the effect of the crystalline properties of the deposited films on process parameters;
such as laser fluence and annealing temperature. In addition, UV-Vis spectroscopy is used to characterize the optical
properties of the deposited ZST films.
We demonstrate a fiber sensing system by using a fiber resonator which is formed by two fiber Bragg gratings. It is able
to measure real time strain and stress directly by the variation of the intensity of the output power due to the modulation
in the fiber resonator. It shows that recording of the strain variation can be achieved as high as 2K Hz. The frequency
response, signal noise ratio, and maximum range of the sensing system are studied with various reflectivity of the FBG,
and the coupling ratios of the couplers used in the system.
In this paper we demonstrated a fiber sensing system using the method of wavelength locking of two nearly identical fiber Bragg gratings (FBG) to interrogate the wavelength shift by directly measuring the intensity of the reflection from the sampling FBG. The light source of the sensing system is based on a fiber ring laser structure in which a reference FBG is used for locking the wavelength of the fiber ring laser pumped by a 980 nm laser diode to achieve lasing at 1555.85 nm. The wavelength locking method is able to an effective way of interrogating the wavelength shifting of a FBG by the intensity of the reflection from the sampling FBG, and is able to achieve real time sensing of the physical perturbations. In addition, the characteristics of the fiber sensing system for dynamic vibration and the key factors to acquire stable sensing are discussed.
Previous results showed that the non-reversible (hystersis loop) of Bragg wave length shifting in thermal cycling of the Fiber Bragg Grating which is a high germanium doped optical fiber and high pressure hydrogen loaded was due to the diffusion out of the H2 residue in thermal annealing. In addition, the O-H absorption peak (1.38nm) causes signal attenuation and stability problem in FBG applications. We demonstrated up to 250 degree(s) C. The spectrum characteristics of the D2 loaded FBG compared to the H2 loaded FBG is presented. In general, (Delta) (Lambda) B of the D2 loaded FBG is narrower than H2 loaded, and (Lambda) B of the D2 loaded FBG is more stable than H2 loaded in thermal annealing. A model base on the UV photo-induced index change in the BFG core with D2 and H2 loaded to explain the spectrum characteristics between D2 and H2 loaded FBG is discussed.
We present the observation of the activity of artemia, one of the popular marine micro-biota species, in free space by the application of Fourier optics imaging technique. The Fourier optic imaging system is consisted by a collimated laser beam source, a Fourier spatial filter, an non-coherent IR source, and a CCD imaging system. By recording the images of Artemia's motion in real life, we are able to study the fundamental patterns of artemia motion mechanism, and the response of the motion pattern to the variation of its environment. Characteristic patterns of artemia's motion, such as linear motion, spiral motion, and mating collision are observed. It is shown that the increasing of the environment temperature driving the motion of the artemia's moving faster and more frequently, and still stays alive even at the environment temperature up to 38 C.
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