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We demonstrated a method of index of refraction measurement for unknown liquids by using a fiber Bragg grating (FBG) which the cladding layer is depleted to enhance the measurement of Bragg wavelength shift due to the variation of the index of the liquid samples. Process of the etching of the cladding layer of the FBG is described, and the procedure to calibrate the wavelength shift of the FBG in variation of standard index oil is discussed. Measurement of index of a sample liquid as high as 1.45 and within accuracy of 0.01 can be achieved, and a FBG signal interrogation system has been integrated to measure the index of refraction of water with different sugar contents.

To improve the sensitivity of a single-mode D-type optical fiber sensor, we selected a D-type optical fiber sensor with 4 mm long and 4 μm core thickness made of a single-mode fiber, a Au-coating on the sensor with a thickness range of 15–32 nm, a light wavelength of 632.8 nm, and an incident angle of 86.5–89.5° for different refractive index (1.33–1.40) sensing. These simulations are based on the surface plasmon resonance (SPR) theory using the phase method which shows that the sensitivity is proportional to the refractive index, Au film thickness and lower incident angle on the sensing interface. The sensitivity is higher than 4000 (degree/RIU), and the resolution is better than 2.5 × 10−6(RIU) as the minimum phase variation is 0.01°. This device is used to detect the refractive index or gas or liquid concentration in real-time. The proposed sensor is small, simple, inexpensive, and provides an in vivo test.

A new method for small displacement measurement based on surface plasmon resonance and heterodyne interferometry is presented. A heterodyne light is focused on a mirror and reflected from it, and then it is incident on a prism which was coated with a thin gold film. When the mirror or the objective lens has a small displacement, the light will be converging or diverging into the prism, and the phase variation between two parts of the test beam under the condition of surface plasmon resonance (SPR) can be measured by using a two-segment photodiode and a lock-in amplifier. This phase difference between two parts of the test beam is proportional to the departure of the mirror from the focal plane, so the displacement can be obtained in real-time. It has some merits, such as, simple, stable, very high sensitivity and resolution. And its resolution is better than 1nm.

-- For improving the sensitivity of a D-type SPR fiber sensor, we simulated the optimum parameters , such as, the thickness of coatings, the length of sensor, and the angle of incidence for different ranges of refractive index. These simulations are based on SPR theory and the intensity and phase methods. It is clearly that, the sensitivity is improved by increasing the length of sensor and/or the thickness of the gold film. And the sensitivity of the phase method is higher than the intensity method by two orders. It is used to detect the refractive index or concentration of gas or liquid in real-time, and it has some merits, such as, small, simple, cheaper, and in vivo test. Keywords : surface plasmon resonance (SPR), fiber sensor 1. INTRODUCTION SPR fiber sensor is very useful in many applications in resent years 1-4 , such as, physical, chemical, biophotonics, etc. Although the sensitivity is not as high as that of the SPR prism sensor, however, owing to its merits such as, low cost, smaller tested volume, convenient to operation, in-vivo testing, it is also attention-getting in the future. There are several types of optical fiber sensor (OFS) based on surface plasmon resonance had been proposed

For improving the sensitivity of a SPR biosensor, we proposed a new combination of the thin silver (Ag) and SiO 2 films, and used the common-path heterodyne interferometry. Although the Ag film has higher sensitivity than the gold (Au) film 1 , but Ag has toxicity for many media and it is easy to be oxidized. In order to enhance the sensitivity and protect the tested medium not to directly contact with Ag, we selected a coating of SiO 2 on the Ag film for the reason of it is cheaper and easy to obtain. The simulations and experimental results are shown that its best resolution could reach to the value of 6.9×10 -9 RIU.

We investigated the reason why butylidenephthalide (Bdph) can have an antianginal effect without changing blood pressure in conscious rats. Isolated dog coronary artery (CA), femoral vein (FV), femoral artery (FA), and mesenteric artery (MA) were used to evaluate the relaxant effects of Bdph. Bdph concentration-dependently relaxed isolated CA, FV, FA, and MA precontracted by KCl (60 mM) and phenylephrine (phe, 5 microM) with the exception that CA was precontracted by prostaglandin F 2 alpha (PGF 2 alpha, 2 microM) instead of phe. The potency order of Bdph to these blood vessels was FV > CA > FA > or = MA. Bdph also concentration-dependently and non-competitively inhibited cumulative KCl (5 - 120 mM)- and phe (0.1 - 100 microM)-induced contractions in normal, and inhibited cumulative Ca 2+-induced contractions in depolarized blood vessels. The potency order of Bdph to these blood vessels was FV congruent with CA > FA congruent with MA. Bdph (0.02 - 0.04 mM) concentration-dependently and leftward-shifted the log concentration-response curves in parallel and significantly increased the pD 2 value of forskolin, but not nitroprusside in FV. Bdph (0.1 mM) did both in CA. Bdph (0.225 - 0.45 mM) did the opposite to that of nitroprusside, but not forskolin, in FA. Bdph (0.45 - 0.9 mM) did neither in MA. Bdph (0.1 - 1 mM) significantly inhibited cAMP- but not cGMP-PDE activities in these four blood vessels, suggesting that Bdph more selectively inhibited the former in these tissues. The above results suggest that the higher potencies of Bdph on FV and CA than on FA and MA, may be interpreted as the reason why Bdph is useful in the treatment of angina pectoris without changing blood pressure, after Bdph administration in vivo, because the venoreturn may be reduced and the coronary flow may be increased without affecting the arterioles, such as MA, the main determinant of blood pressure. Abbreviations. Bdph:butylidenephthalide Phe:phenylephrine PGF 2alpha :prostaglandin F 2alpha CA:coronary artery FV:femoral vein FA:femoral artery MA:mesenteric artery cAMP:adenosine 3',5'-cyclic monophosphate cGMP:guanosine 3',5'-cyclic monophosphate PDE:phosphodiesterase