Study On Micro-nanofibers’ Fabrication And Their Sensitive Characteristics

Fabrication, optical properties research and application of micro-nano optical fiber are one of the frontier nanometer materials on current international research. Micro-nano optical fiber with low optical loss, strong evanescent field effect, strong restraint of mode field, small size and other good characteristics, is treated as the most basic unit module of the next generation integrated micro/nano system. Micro- nano optical fiber also can be surface modification and functional mixed, that makes it wider use. It can be not only serve as a optical path coupling between the micro/nano device, but also as an independent device at the same time. In recent years, with the development of micro-nano processing technology and advanced integration technology, new material of micro- nano optical fiber is used in various functional micro-nano devices and integrated system. In particularly, in combination with a variety of cross science, micro-nano fiber has a bigger and more wide application prospect.However study of micro-nano optical fiber is still in its early stage. Especially on the 3d precise fabrication is insufficient, which limits the further development of micro- nano optical fiber devices. In this thesis, on the one hand, we proposed the devisable nanofiber with high integration and precision by femtosecond laser direct writing technique; To some extent, and implements a custom micro- nano devices. O n the other hand, combining the micro-nano fiber and optical fiber sensing technology, we proposed an optical magnetic field sensor with the temperature correction capability. This article mainly includes the following contents:Nanofiber was fabricated by femtosecond laser direct writing technique. The micro-nano optical fiber parameters(cross section, the thickness, length, arrangement, etc.) can be designed in this technique in advance, and then is fabricated efficiently according to the design scheme. In this paper, devisable nanofiber with high integration and precision is fabricated by femtosecond laser direct writing technique. Among them, the line width of the smallest nanofiber can reach about 200 nm. From SEM, we find that surface of line width 600 nm nanofiber is relatively smooth, continuous uninterrupted. To some extent, this method can realize the customization of micro- nano devices. Through the study of fabricated nanofiber, we found that between 400 nm to 800 nm through rate of 90% or more; And transmission loss is about 0.03 d B·μ m-1 in 532 nm green light.Magnetic field sensors integrated microfiber taper and magnetic fluid. The microfiber taper in the sensor prob e was fabricated on common telecom single- mode optical fiber in the fusion splicer with additional tension on one side. Considering on the sensitivity and detection limit, We found that the microfiber taper diameter of 7.8μ m, length of about 450μ m is suitable for magnetic field sensor through magnetic field test experiment of different diameter size microfiber. From the magnetic field test, we found that the spectrue red shift move relatively slowly in magnetic field strength 0-20 Oe period; the linear relationship in the range of 20-70 Oe is obvious, the sensitivity of Peak A and Peak B in this paragraph were 0.171 nm/Oe and 0.084 nm/Oe. When the magnetic field intensity is more than 80 oe, magnetic liquid is saturated, Peak A and Peak B are no longer move. Moreover, there is a linear relationship between the wavelength shift and temperature in the range of 30 °C–80 °C, and a sensitivity of-0.587 nm/°C has been achieved. Based on these experiments, we provided a sensitivity matrix to correct the errors caused by temperature in order to measure magnetic field more accurately.