Benli Yu

High-sensitivity Fabry-Perot interferometric pressure sensor based on a nanothick silver diaphragm.

We present a fiber-optic extrinsic Fabry-Perot interferometer pressure sensor based on a nanothick silver diaphragm. The sensing diaphragm, with a thickness measured in a few hundreds of nanometers, is fabricated by the electroless plating method, which provides a simple fabrication process involving a high-quality diaphragm at a low cost. The sensor exhibits a relatively linear response within the pressure variation range of 0-50 kPa, with a high pressure sensitivity of 70.5 nm/kPa. This sensor is expected to have potential applications in the field of highly sensitive pressure sensors.

Fiber-optic acoustic pressure sensor based on large-area nanolayer silver diaghragm

A fiber-optic acoustic pressure sensor based on a large-area nanolayer silver diaphragm is demonstrated with a high dynamic pressure sensitivity of 160  nm/Pa at 4 kHz frequency. The sensor exhibits a noise limited detectable pressure level of 14.5  μPa/Hz(1/2). Its high dynamic pressure sensitivity and simple fabrication process make it an attractive tool for acoustic sensing and photo-acoustic spectroscopy.

Self-mixing interference measurement system of a fiber ring laser with ultra-narrow linewidth

A novel device for self-mixing interference measurement based on the fiber ring laser with ultra-narrow linewidth was investigated for the first time. In order to achieve requirement of our measurement system, a saturable-absorber which consists of a segment un-pumped erbium-doped fiber and a fiber Bragg grating is employed to provide a fine mode selection and guarantee the ultra-narrow linewidth operation. Results demonstrate that the signal-to-noise ratio of the self-mixing interference signal could be enhanced from 18.01 dB to 38.35 dB by inserting a saturable-absorber in the laser cavity. It is in good agreement with the theoretical analysis and proved potential using in self-mixing interference measurement system for high sensitivity and remote measurement.

Self-Mixing Signal in

The self-mixing sensing technique is a compact sensing technique that can be used for measuring distances, displacements, velocities, and vibration. In this letter, for good sensitivity remote measurement, self-mixing interference using an Er3+-Yb3+ Distributed Bragg Reflector (EYDBR) fiber laser is proposed and investigated for the first time. Results demonstrate that the EYDBR fiber laser presents a powerful tool for the self-mixing sensor and provides a remote measurement of the displacement and the vibration up to 20 Km.

{\rm Er}^{3+}-{\rm Yb}^{3+}

In this paper, we present a method of velocity measurement using of a novel self-mixing velocimeter with orthogonal-beam incident system (OSMV), which enables the velocity measurement without knowing the incident angle information. The fiber ring laser used could provide a stable and narrow-width laser light source, which could enhance the stability and the signal-to-noise ratio of the novel self-mixing fiber ring laser velocimeter. The result indicates a much better linearity of our novel velocimeter than the traditional one in the turntable experiment due to the use of the orthogonal-beam incident system and fiber ring laser source. The relative error rates of our novel velocimeter system are up to 1.258% in contrast with the 13.720% result of the traditional one.

Codoped Distributed Bragg Reflector Fiber Laser for Remote Sensing Applications up to 20 Km

Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade.

Self-Mixing Fiber Ring Laser Velocimeter With Orthogonal-Beam Incident System

A compact fiber sensor based on fiber Bragg grating (FBG) embedded in a fiber modal interferometer (MI) for simultaneous measurement of strain and temperature is proposed. Because the total length of the sensor is 12 mm and can be further reduced, the spatial resolution of the sensor is improved. Due to the different responses of the fiber MI and the FBG to strain and temperature, the simultaneous measurement at the same point is achieved. For 0.01-nm wavelength resolution, the resolution of the sensor is 5.96 με and 0.31 °C in strain and temperature, respectively.

Contributed Review: Quantum cascade laser based photoacoustic detection of explosives

The dual-channel self-mixing vibration measurement system in a linear cavity fiber laser with high sensitivity, flexibility, and potential remote sensing is proposed and studied in this paper. In addition, the output power with optical feedback is theoretically deduced and simulated on the basis of the three-cavity model. Experimental results show that the different movements of each channel can be detected from the dual-channel linear cavity fiber laser self-mixing interference system on the basis of the filter technology and that are in good agreement with the theoretical analysis. In addition, this paper introduces a new way to measure two-dimensional vibration.

Compact Fiber Sensor With High Spatial Resolution for Simultaneous Strain and Temperature Measurement

We present a theoretical analysis and a comparison to experimental results on self-mixing interference. From the theoretical analysis and experiment, the error of the velocity measurement, which is caused by a speckle pattern, has been investigated and optimization of the laser diode velocity system by selecting suitable experiment parameters and proper signal processing methods has been reported. The actual measurement error is <3.1% over a wide velocity range (5.2-479 mm/s).

Dual-Channel Self-Mixing Vibration Measurement System in a Linear Cavity Fiber Laser

We investigate the optical bistability and multistability in donor and acceptor quantum dots embedded in a nonlinear photonic crystal inside an optical ring cavity. It is found that the optical bistability and multistability can be easily controlled via adjusting properly the corresponding parameters of the system. The effect of the dipole–dipole interaction has also been included in the formulation, which leads to interesting phenomena. Our scheme opens the possibility to control the optical bistability and multistability in photonic materials doped with nanoparticles.