Yiyang Zhuang

A Displacement Sensor With Centimeter Dynamic Range and Submicrometer Resolution Based on an Optical Interferometer

We report a low cost and extrinsic Fabry-Perot interferometer-based optical fiber displacement sensor with a wide dynamic range, up to 2.0 cm, and

An Optical Interferometric Triaxial Displacement Sensor for Structural Health Monitoring: Characterization of Sliding and Debonding for a Delamination Process

0.270~\mu \text{m}

An embeddable optical strain gauge based on a buckled beam

resolution. The fundamental design principle includes an inclined mirror, mounted on a translational stage, that combines with the end face of a single mode fiber to form a Fabry-Perot cavity. The user-configurable triangle geometry-based displacement transfer mechanism makes the sensor capable of measuring a wide displacement range. A fiber ceramic ferrule is used to support and orient the optical fiber, and a metal shell is used to package and protect the principal sensor elements. The novel sensor was employed to monitor shrinkage during the drying/curing stage of a square brick of mortar. The robust and easy-to-manufacture sensor can be easily commercialized and has great potential for applications in the chemical-oil industry, construction industry, and other industries with harsh environments.

Displacement and Strain Measurement up to 1000 °C Using a Hollow Coaxial Cable Fabry-Perot Resonator

This paper presents an extrinsic Fabry–Perot interferometer-based optical fiber sensor (EFPI) for measuring three-dimensional (3D) displacements, including interfacial sliding and debonding during delamination. The idea employs three spatially arranged EFPIs as the sensing elements. In our sensor, the three EFPIs are formed by three endfaces of three optical fibers and their corresponding inclined mirrors. Two coincident roof-like metallic structures are used to support the three fibers and the three mirrors, respectively. Our sensor was calibrated and then used to monitor interfacial sliding and debonding between a long square brick of mortar and its support structure (i.e., a steel base plate) during the drying/curing process. This robust and easy-to-manufacture triaxial EFPI-based 3D displacement sensor has great potential in structural health monitoring, the construction industry, oil well monitoring, and geotechnology.

A hollow coaxial cable Fabry–Pérot resonator for liquid dielectric constant measurement

We report, for the first time, a low cost, compact, and novel mechanically designed extrinsic Fabry-Perot interferometer (EFPI)-based optical fiber sensor with a strain amplification mechanism for strain measurement. The fundamental design principle includes a buckled beam with a coated gold layer, mounted on two grips. A Fabry-Perot cavity is produced between the buckled beam and the endface of a single mode fiber (SMF). A ceramic ferrule is applied for supporting and orienting the SMF. The principal sensor elements are packaged and protected by two designed metal shells. The midpoint of the buckled beam will experience a deflection vertically when the beam is subjected to a horizontally/axially compressive displacement. It has been found that the vertical deflection of the beam at midpoint can be 6-17 times larger than the horizontal/axial displacement, which forms the basis of a strain amplification mechanism. The user-configurable buckling beam geometry-based strain amplification mechanism enables the strain sensor to achieve a wide range of strain measurement sensitivities. The designed EFPI was used to monitor shrinkage of a square brick of mortar. The strain was measured during the drying/curing stage. We envision that it could be a good strain sensor to be embedded in civil materials/structures under a harsh environment for a prolonged period of time.

Unclonable Optical Fiber Identification Based on Rayleigh Backscattering Signatures

We present a hollow coaxial cable Fabry-Perot resonator for displacement and strain measurement up to 1000 °C. By employing a novel homemade hollow coaxial cable made of stainless steel as a sensing platform, the high-temperature tolerance of the sensor is dramatically improved. A Fabry-Perot resonator is implemented on this hollow coaxial cable by introducing two highly-reflective reflectors along the cable. Based on a nested structure design, the external displacement and strain can be directly correlated to the cavity length of the resonator. By tracking the shift of the amplitude reflection spectrum of the microwave resonator, the applied displacement and strain can be determined. The displacement measurement experiment showed that the sensor could function properly up to 1000 °C. The sensor was also employed to measure the thermal strain of a steel plate during the heating process. The stability of the novel sensor was also investigated. The developed sensing platform and sensing configurations are robust, cost-effective, easy to manufacture, and can be flexibly designed for many other measurement applications in harsh high-temperature environments.

A Microwave Photonics Fiber Loop Ring-Down System

We report, for the first time, a low-cost and robust homemade hollow coaxial cable Fabry-Pérot resonator (HCC-FPR) for measuring liquid dielectric constant. In the HCC design, the traditional dielectric insulating layer is replaced by air. A metal disk is welded onto the end of the HCC serving as a highly reflective reflector, and an open cavity is engineered on the HCC. After the open cavity is filled with the liquid analyte (e.g., water), the air-liquid interface acts as a highly reflective reflector due to large impedance mismatch. As a result, an HCC-FPR is formed by the two highly reflective reflectors, i.e., the air-liquid interface and the metal disk. We measured the room temperature dielectric constant for ethanol/water mixtures with different concentrations using this homemade HCC-FPR. Monitoring the evaporation of ethanol in ethanol/water mixtures was also conducted to demonstrate the ability of the sensor for continuously monitoring the change in dielectric constant. The results revealed that the HCC-FPR could be a promising evaporation rate detection platform with high performance. Due to its great advantages, such as high robustness, simple configuration, and ease of fabrication, the novel HCC-FPR based liquid dielectric constant sensor is believed to be of high interest in various fields.

Probing Nanostrain via a Mechanically Designed Optical Fiber Interferometer

We report a concept of using Rayleigh backscattering signature based unclonable optical fiber identification (OFID) for security-based applications. Due to the inherent manufacturing features of optical fibers, the random Rayleigh backscattering pattern within an optical fiber can be used for identification. We also experimentally demonstrated the OFID idea. Cross correlation in the spatial domain and encoding techniques are applied to verify the authenticity of OFID. Also, it has been demonstrated that the proposed OFID device can survive the high-temperature harsh environment. This robust, reliable, and flexible OFID method has great potential for a variety of applications, such as security, recognition, encryption, identification, and authentication.

Rayleigh backscattering based macrobending single mode fiber for distributed refractive index sensing

A microwave photonics fiber loop ring-down system is demonstrated in this paper. In comparison with the traditional time domain fiber loop ring-down setup, the demonstrated system is based on pure frequency domain measurement from a microwave-photonic configuration. The system consists of a direct-modulation laser with its modulation frequency scanned by a vector network analyzer. The amplitude and phase spectra of the demonstrated fiber loop ring-down system are then recorded, followed by a complex Fourier transform to acquire the ring-down curve in the time domain. The loss of the fiber loop can then be evaluated based on the calculated ring-down curve. The system delivers high signal-to-noise ratio, and averaging is not required compared with the traditional time domain measurement. The system is also insensitive to the sources of environmental noise. The measurement principle, experimental setup, and the mathematical model of the system are discussed in this paper. A proof-of-concept macrobending loss test is demonstrated.