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We theoretically and experimentally demonstrate a fiber-optic ultrasonic sensor system based on a fiber-ring laser whose cavity consisting of a regular fiber Bragg grating (FBG) and a tunable optical band-pass filter (TOBPF). The FBG is the sensing element and the TOBPF is used to set the lasing wavelength at a point on the spectral slope of the FBG. The(More)
We propose and demonstrate an intensity-demodulated fiber-optic ultrasonic sensor system that can be self-adaptive to large quasi-static background strain perturbations. The sensor system is based on a fiber ring laser (FRL) whose laser cavity includes a pair of fiber Bragg gratings (FBGs). Self-adaptive ultrasonic detection is achieved by a tandem design(More)
Hierarchical nanostructures that can be directly grown on a conducting substrate are a new trend in the design of active materials for high-performance lithium-ion batteries (LIBs). This article reports our design and fabrication of a 3D hierarchical ZnCo2O4 nanostructure (3D-ZCO-NS) directly grown on Ni foams. The goose-feather-like ZnCo2O4 bundled into a(More)
A facile hydrothermal method is developed for large-scale production of three-dimensional (3D) hierarchical porous nickel cobaltate nanowire cluster arrays derived from nanosheet arrays with robust adhesion on Ni foam. Based on the morphology evolution upon reaction time, a possible formation process is proposed. The role of NH4F in formation of the(More)
A fiber-optic refractive index (RI) sensor based on a π-phase-shifted fiber-Bragg-grating (πFBG) inscribed on a side-hole fiber is presented. The reflection spectrum of the πFBG features two narrow notches associated with the two polarization modes and the spectral spacing of the notches is used for high-sensitivity RI sensing with little temperature(More)
We propose and demonstrate a multiplexing method for ultrasonic sensors based on fiber Bragg gratings (FBGs) that are included inside the laser cavity of a fiber-ring laser. The multiplexing is achieved using add-drop filters to route the light signals, according to their wavelengths, into different optical paths, each of which contains a separate span of(More)
Electrochemical supercapacitors have drawn much attention because of their high power and reasonably high energy densities. However, their performances still do not reach the demand of energy storage. In this paper β-cobalt sulfide nanoparticles were homogeneously distributed on a highly conductive graphene (CS-G) nanocomposite, which was confirmed by(More)
We propose and demonstrate a simple and low-cost method to lock the wavelength of a diode laser to a point with a particular normalized slope on the spectrum of a fiber-optic sensor. The wavelength locking point is independent of the laser intensity variations. The locking involves simultaneously and independently modulating both the laser wavelength and(More)
We theoretically and experimentally investigate the performance of an ultrasound detection system based on a fiber ring laser (FRL) whose cavity includes a pair of fiber Bragg gratings. The ultrasonic detection is achieved by the FRL power variations in response to the ultrasound-induced cold-cavity loss modulation of the FRL. The effects of key FRL(More)
In an ultrasonic sensor system based on π phase-shifted fiber Bragg gratings (πFBGsÞ, a cost-effective way for sensor demodulation is to set the laser wavelength at the center of the steep spectral slope of the πFBG refection spectrum. Frequency noise of the laser source ultimately limits the signal-to-noise ratio (SNR) of the(More)