Shuji Taue

Sensitivity Characteristics of Multimode-Interference Optical-Fiber Temperature-Sensor With Solid Cladding Material

A simple analytical calculation method providing convenient design criteria for the realization of high sensitivity temperature sensor is presented. Such an approach is applicable to any type of multimode interference (MMI) structure with different core/cladding compositions. A low-complexity optical-fiber temperature sensor, based on MMI using epoxy resin as a solid cladding material, is evaluated with wavelengths ranging from 1200 to 1700 nm. We analytically proved a mechanism providing high temperature sensitivity of the MMI sensor with solid cladding material, whose refractive index depends on the wavelength. The temperature sensitivity around a wavelength of 1200 nm is -0.96 nm/°C, while at 1650 nm is -5.96 nm/°C, which is more than six times larger. These results agree well with the proposed simple calculation model.

High sensitivity optical-fiber temperature sensor with solid cladding material based on multimode interference

We have developed a high-sensitivity fiber temperature sensor using multimode interference. It comprises a multi-mode-fiber (MMF) sandwiched between single-mode-fibers. The MMF is coated with epoxy resin, whose refractive index is close to that of MMF.

AC magnetic field imaging by using digital micro-mirror device

We demonstrated optical imagings of AC magnetic fields. A digital micro-mirror device and a lock-in detection allowed obtaining sub-millimeter resolution images without using magnetic shields. Images of gradient field from a wire suggested its potential to apply for signal-source estimations.

Reflection-type fiber-optic multimode interference structure with rounded end-face: A temperature-sensing study

We investigated a novel reflection technique for a reflection-type fiber-optic multimode interference structure. Rounding the fiber end-face increased the reflected light intensity by more than 10 dB, with no reflection coating. We demonstrated the use of our multimode interference structure as a temperature sensor by immersing the sensing region in temperature-controlled silicone oil. The resulting sensitivity was 0.028°C for a 29.60-mm sensing region.

Surface plasmon absorption characteristics of gold deposited on optical fibers

We deposited gold films on optical fiber surfaces and annealed them to analyze the absorbance in the visible and near infrared wavelength range. The corresponding relations between the absorption spectra and the structural images of the deposited gold were identified.