Linyong Fan

Experimental research of temperature sensor based on twin-core fiber

A low-cost, compact, and lossless temperature sensor based on a twin-core fiber (TCF) is demonstrated and manufactured by splicing two single-mode fibers to the ends of a TCF. The extinction ratio of the comb transmission spectrum is bigger than 15 dB, and the temperature sensitivity of the coupling angle is -0.02 rad/(oC.m) at -30-90 oC and -0.032 rad/(oC.m) at 90-175 oC. Finite element method is used to calculate the supermodes of the TCF, and the result agrees well with the experiment.

Influences on the bandwidth at the drop port of the add/drop filter using a fiber grating coupler by uniform and linearly chirped fiber Bragg grating

Writing a fiber Bragg grating (FBG) in an optical fiber coupler is a very effective way to implement an optical add/drop filter (OADF). In order to analyze the influences on the bandwidth at the drop port of the OADF using fiber grating-assisted mismatched coupler, a uniform FBG and a linearly chirped FBG were written on the coupler, and two different OADFs were fabricated. The fiber grating is written in a 2×2 mismatched coupler, which is fused and tapered with a standard single mode fiber (SMF) and a high germanium doped photosensitive fiber, by using a 248 nm ultraviolet laser. For the OADF using the uniform FBG, the 3 dB and 20 dB bandwidths are 0.1 nm and 0.3 nm, respectively; for the OADF using the linear chirped FBG, the 3 dB and 20 dB bandwidths are 0.8 nm and 2 nm, respectively. The experimental results meet the theoretical analysis well. The bandwidth at the drop port of the device can be adjusted by adjusting the chirped coefficient of the linearly chirped FBG.

Comb-Filter Based on In-Fiber Mach-Zehnder Interferometer Using a Twin-Core Fiber

A comb-filter based on in-fiber Mach-Zehnder interferometer (MZI) is experimentally fabricated by splicing a section of single mode noncircular twin-core fiber (TCF) between two single mode fibers (SMFs). The wavelength spacing between the adjacent transmission peaks was numerically and experimentally analyzed, and it is associated with the effective index difference of the two cores and the length of the TCF. The wavelength spacing between the adjacent transmission peaks can be narrowed by increasing the length of the TCF or the effective index difference of the two cores. This device is compact and easy to be fabricated.

All-fiber optical attenuator based on eccentric core single-mode fiber

All-fiber optical attenuators based on an eccentric core single-mode fiber, whose core is away from the axis of the fiber, are demonstrated. By controlling the distance between the core and the axis of the fiber, attenuators with different attenuation can be made. The device is simple, reliable, and economical.

Precise method for modifying birefringence of stress-induced high-birefringence fiber

A precise method for modifying the birefringence of stress-induced high-birefringence (Hi-Bi) fiber is demonstrated by side polishing a Panda-type fiber with a maximum polished length of at least 14 cm. The polishing depth is controlled with an accuracy of 0.1 microm by piezoelectric ceramic microdisplacement. The accuracy of the birefringence is of the order of 10(-6). This method allows high-quality Hi-Bi fiber segments to be conveniently implemented with low loss at any desired birefringence between 3.17 x 10(-4) and 7.5 x 10(-5) in our experiment from one stress-induced Hi-Bi fiber and without changing the directions of the stress axes. The finite-element method is used to simulate the procedure, and the numerical results agree with the experiment.

Growth of Ultraviolet-induced H 2 -loaded long period fiber grating immediately after fabrication

The growth of long period fiber grating written in H2-loaded fiber within one hour immediately after fabrication was measured and analyzed. Fast deepen on difference of refraction index was obviously observed in all the experiments, but the peak wavelength to time and cross-coupling coefficient to time curves are fitted better in exponential decay function than power function, and suggest a same variation pattern in difference of refraction index.