Zhangqi Song

Microparticle Detection With Optical Microfibers

We demonstrate a method for microparticle detection with an optical microfiber (OM). When a microparticle adheres to the uniform waist region of an OM, the transmitted loss of OM will increase due to the evanescent field perturbation. The additional loss of OM, caused by the adhered microparticle with different refractive indices and diameters, has been researched and simulated based on the evanescent field theory. We experimentally demonstrate the possibility of the method with a simple setup. Dust and alumina microparticles are detected. Experimental results have shown that the diameter of dust microparticle and the number of adhered alumina microparticles, can be estimated by measuring the additional loss of the sensing OM.

Precise control of the optical microfiber tapering process based on monitoring of intermodal interference

This paper describes the effective rectification of the estimated diameter of an optical microfiber (OM) during the tapering process. A high-coherence laser is used to monitor the OM-tapering process. The evolution of the intermodal interference between the fundamental mode and the coupled modes can be clearly observed. We analyze the point in time at which the excited mode vanishes and use that to justify the correlative diameter of the fabricated OM for the first time, to the best of our knowledge. By comparing the measured cutoff time of the coupled LP(02) mode and the theoretically predicted value, we can judge whether the theoretical estimation of the OM diameter has been correctly obtained, and we can introduce a modification method with feedback by changing the initial parameters or the manufacturing conditions to ensure OM diameter accuracy. This identification and rectification method is helpful for precise fabrication of OMs with different waist lengths and waist diameters, and it can also be used to check the repeatability of OMs.

Refractive index sensor based on optical fiber end face using pulse reference-based compensation technique

We proposed a refractive index sensor based on optical fiber end face using pulse reference-based compensation technique. With good compensation effect of this compensation technique, the power fluctuation of light source, the change of optic components transmission loss and coupler splitting ratio can be compensated, which largely reduces the background noise. The refractive index resolutions can achieve 3.8 × 10-6 RIU and1.6 × 10-6 RIU in different refractive index regions.

Tiny optical fiber temperature sensor based on temperature-dependent refractive index of zinc telluride film

The temperature-dependent refractive index of zinc telluride film can be used to develop a tiny, low cost and film-coated optical fiber temperature sensor. Pulse reference-based compensation technique is used to largely reduce the background noise which makes it possible to detect the minor reflectivity change of the film in different temperatures. The temperature sensitivity is 0.0034dB/℃ and the background noise is measured to be 0.0005dB, so the resolution can achieve 0.2℃.

Optical fiber acoustic sensor with an all-optical phase modulator based on special optical microfiber

An optical fiber acoustic sensor with improved all-optical phase modulator based on special optical microfiber is introduced, which can realize all-fiber structure through remotely intensity-modulating the modulator with a semiconductor laser with 980nm wavelength.