In this Letter we report on fabricating and analyzing a temperature insensitive refractometer based on two concatenated dual-resonance long-period gratings (LPGs) with an appropriate inter-grating space (IGS) in between. The IGS provides a temperature-dependent extra phase difference between the core and cladding modes, making the refractometer similar to a Mach-Zehnder interferometer with its ...

A compact single-mode photonic crystal fiber single-mode fiber tip (SPST) refractive index sensor is demonstrated in this Letter. A CO2 laser cleaving technique is utilized to provide a clean-cut fiber tip, which is then coated by a layer of gold to increase reflection. An average sensitivity of 39.1 nm/RIU and a resolvable index change of 2.56×10(-4) are obtained experimentally with a ∼3.2 μm ...

This paper presents the design and analysis of a liquid refractive index sensor that utilizes a unique physical mechanism of resonant optical tunneling effect (ROTE). The sensor consists of two hemicylindrical prisms, two air gaps, and a microfluidic channel. All parts can be microfabricated using an optical resin NOA81. Theoretical study shows that this ROTE sensor has extremely sharp transmis...

A new system, consisting of a double channel Fabry Perot etalon and laser diodes emitting around 780 nm is described and proposed to be used for air refractive index measurements. The principle of this refractometer is based on frequency measurements between optical laser sources. It permits quasi-instantaneous measurement with a resolution better than 10 9 − and uncertainty in the 10 8 − range...

According to early examination (Vojniković, 1978) estimated, that the index of refraction for aqueous and vitreous is not the sum (1.33 or 1.66), than is for aqueous n = 1.334, and for vitreous N = 1.336. This measurements are made with Abbe's refractometer, by temperature of 33 degrees C for aqueous, and 36 degrees C for vitreous, as it's in human eye. In the principle of these results, the au...

Refractometry using a Brix refractometer has been proposed as a means to estimate IgG concentration in bovine maternal colostrum (MC). The refractometer has advantages over other methods of estimating IgG concentration in that the Brix refractometer is inexpensive, readily available, less fragile, and less sensitive to variation in colostral temperature, season of the year and other factors. Sa...