Wa Jin

Air-Holes Collapse Properties of Photonic Crystal Fiber in Heating Process by

For the fusion splicing of photonic crystal fiber (PCF), the air-hole collapse in heating process is important for minimizing the splicing loss. To analyze the air-hole collapse properties in heating process by CO2 laser, a theoretical model of PCF has been proposed. The variation relationships among the splicing loss, air-hole collapse, and heating time are analyzed, respectively. The results show that the theoretical simulation is basically in accordance with the experimental data. Thus, the air-hole collapse can be controlled by adjusting the splicing power and heating time. Errors are also given.

\hbox{CO}_{2}

We report the first fabrication of a polarization converter in a highly birefringent elliptical microfiber, which is made by periodically twisting a microfiber with an ellipticity of ∼0.7 and a diameter of ∼2.8 along its major axis. Strong input polarization suppression of ∼20 dB is achieved at a resonant wavelength of ∼1556.4 nm with a device length of ∼3.12 mm, one or even more two orders of magnitude shorter than that fabricated in the conventional Hi-Bi fiber. This device demonstrates temperature stability, which is of 15pm/O.

Laser

We report the fabrication of long-period gratings (LPGs) in elliptical microfibers with femtosecond laser. Based on the numerical analysis of the modes and the mode coupling condition of elliptical microfibers, an LPG is fabricated with a very short pitch of by periodically modifying the fiber surface, which demonstrates very strong polarization-dependent resonances, a very low temperature sensitivity of a few picometers in air, and high temperature sensitivity of −1.62 nm/°C in refractive index oil.

Temperature insensitive structural polarization converters in highly birefringent microfibers

In view of the current poor learning initiative of undergraduates, the idea of creating a good learning environment and motivating active learning enthusiasm is proposed. In practice, the professional tutor is allocated and professional introduction course is opened for college freshman. It can promote communication between the professional teachers and students as early as possible, and guide students to know and devote the professional knowledge by the preconceived form. Practice results show that these solutions can improve the students interest in learning initiative, so that the active learning and self-learning has become a habit in the classroom.

Numerical and experimental analysis of long period gratings in wavelength scale elliptical microfibers

A refractive index sensor based on taper Michelson interferometer in multimode fiber is proposed. The Hydrofluoric acid corrosion processing is studied in the preparation of single cone multimode optical fiber sensor. The taper Michelson interferometer is fabricated by changing corrosion time. The relationship between fiber sensor feature and corrosion time is analyzed. The experimental results show that the interference spectrum shift in the direction of short wave with the increase of the refractive index. The refractive index sensitivity can reach 115.8008 nm/RIU. Thereby, it can be used in detecting the refractive index in different areas including the environmental protection, health care and food production.

Create a good learning environment and motivate active learning enthusiasm

Heat transfer is very complicate in fusion splicing process of photonic crystal fibers (PCFs) due to different structures and sizes of air hole, which requires different fusion splicing power and offsets of heat source. Based on the heat transfer characteristics, this paper focus on the optimal splicing offset splicing the single mode fiber and PCFs with a CO 2 laser irradiation. The theory and experiments both show that the research results can effectively calculate the optimal fusion splicing offset and guide the practical splicing between PCFs and SMFs.

A refractive index sensor based on taper Michelson interferometer in multimode fiber

With the development of optical fiber manufacture and optical fiber sensor technology, more and more attention is paid to the photonic crystal fiber (PCF) sensors, such as gas sensors, bend sensors and strain sensors. Especially, the bend character of PCF is very important for designing bend sensors. In this paper, we adopt the multipole method to study the bend character of Total Internal Reflection PCF (TIR-PCF), and the relationship between bend radius and bend loss of TIR-PCF is investigated theoretically. As a result, the bend loss of PCF will be variable according to bend radius and it is also different with the same bend radius as the TIR-PCF structure parameter is different. Furthermore, the bend stress distribution on the TIR-PCF is analyzed carefully, and the minimum endurable bend radius is given. The simulation result in this paper will provide primary references for the PCF bend sensors designing.