Mingran Quan

Ultra-high sensitivity Fabry-Perot interferometer gas refractive index fiber sensor based on photonic crystal fiber and Vernier effect.

An ultra-high sensitivity open-cavity Fabry-Perot interferometer (FPI) gas refractive index (RI) sensor based on the photonic crystal fiber (PCF) and Vernier effect is proposed and demonstrated. The sensor is prepared by splicing a section of PCF to a section of fiber tube fused with a section of single mode fiber. The air holes running along the cladding of the PCF enable the gas to enter or leave the cavity freely. The reflection beam from the last end face of the PCF is used to generate the Vernier effect, which significantly improves the sensitivity of the sensor. Experimental results show that the proposed sensor can provide an ultra-high RI sensitivity of 30899 nm/RIU. This sensor has potential applications in fields such as gas concentration analyzing and humidity monitoring.

Fast response Fabry–Perot interferometer microfluidic refractive index fiber sensor based on concave-core photonic crystal fiber

We report a fast response microfluidic Fabry-Perot (FP) interferometer refractive index (RI) fiber sensor based on a concave-core photonic crystal fiber (CPCF), which is formed by directly splicing a section CPCF with a section of single mode fiber. The CPCF is made by cleaving a section of multimode photonic crystal fiber with an axial tension. The shallow concave-core of CPCF naturally forms the FP cavity with a very short cavity length. The inherent large air holes in the cladding of CPCF are used as the open channels to let liquid sample come in and out of FP cavity. In order to shorten the liquid channel length and eliminate the harmful reflection from the outside end face of the CPCF, the CPCF is cleaved with a tilted tensile force. Due to the very small cavity capacity, the short length and the large sectional area of the microfluidic channels, the proposed sensor provides an easy-in and easy-out structure for liquids, leading to great decrement of the measuring time. The proposed sensor exhibits fast measuring speed, the measuring time is less than 359 and 23 ms for distilled water and pure ethanol, respectively. We also experimentally study and demonstrate the superior performances of the sensor in terms of high RI sensitivity, good linear response, low temperature cross-sensitivity and easy fabrication.

Observation of Bright-Dark Soliton Pair in a Fiber Laser With Topological Insulator

The bright-dark soliton pair in a passively mode-locked fiber laser based on the topological insulator: Bi2Se3/polyvinyl alcohol (PVA) film in the proper polarization state and the pump power is experimentally demonstrated. By carefully adjusting the pump power and the polarization state, the bright-dark soliton pair could be easily observed. Furthermore, it is found experimentally that the formation of the bright-dark soliton pair is mainly due to the polarization effect based on the high nonlinear effect of topological insulator: Bi2Se3/PVA film. We also demonstrate that the pulse shape of the bright-dark soliton pair can be affected by the total net cavity dispersion in the fiber laser.

Tunable Multiwavelength Er-Doped Fiber Laser With a Two-Stage Lyot Filter

A switchable and tunable multiwavelength erbium-doped fiber laser is proposed and demonstrated based on a two-stage Lyot filter and intensity-dependent loss (IDL) effect induced by a nonlinear optical loop mirror (NOLM). The proposed laser can achieve multi-parameter individually tuning functions, such as adjusting the channel-spacing, number, and spectral-range of lasing line. The channel spacing can be switched via adjusting the beam’s polarization in the Lyot filter among 0.53, 0.78, and 1.56 nm. Meanwhile, the number and the spectral range of the multiwavelength lasing line can be independently controlled by IDL modulation through the combination of adjusting pump power and the birefringence in the loop of the NOLM. The individual tuning method of the proposed laser on each specific output characteristic provides more convenience and practicality to the applications.

Study on the response speed of fabry–perot interferometer gas pressure fiber sensor based on photonic crystal fiber and vernier effect

A fast response fiber-optic gas pressure Fabry-Perot interferometer is demonstrated. The results show that the response time is 218 and 208 ms, respectively, when the gas pressure increases from 140 to 142 PSI and decreases from 170 to 167 PSI.

Study on the influence of Mach–Zehnder interferometers to the output characteristics of multiwavelength erbium-doped fiber laser

Serving as a frequency selective device, comb filter is a very important component to the multiwavelength erbium-doped fiber laser. There are all kinds of comb filters, among which the Mach–Zehnder interferometer (MZI) is the commonly used one. Since each types of Mach–Zehnder interferometers have its output features, then the study of its influence to the output characteristics of multiwavelength erbium-doped fiber laser is necessary. In this paper, the filtering properties of three basic Mach–Zehnder interferometer are discussed, including single-pass MZI, dual-pass MZI, dual-pass MZI with a optical isolator embedded into the second loop. Furthermore, the working principle and tunable operation of the tunable modified dual-pass MZI are analyzed. Above all, the influence of the four types of MZI to the output characteristics of multiwavelength erbium-doped fiber laser is experimentally studied. The results of this paper are helpful to understand the working principle of these comb filters and improve the output performance of multiwavelength erbium-doped fiber laser.

Performance study on a tunable multiwavelength erbium-doped fiber laser based on nonlinear optical loop mirror and Lyot birefringence fiber filter

In this paper, the performance study on the tunable multiwavelength erbium-doped fiber laser is conducted, which is based on combination of Lyot birefringence fiber filter and nonlinear fiber loop mirror. The method to achieve its optimal working is introduced in detail. The parameters choice based on the best tunability is analyzed from three different perspectives: gain medium, nonlinear effect and comb filter, respectively. All the experimental results will be given through several panels of comparison experiments. The optimal performance will finally be achieved by setting appropriate parameters. The study in this paper will further improve the function of tunable fiber filter.