1,093 research outputs found
Advances in Fiber-Optic Extrinsic Fabry-Perot Interferometric Physical and Mechanical Sensors: A Review
Fabry-Perot Interferometers Have Found a Multitude of Scientific and Industrial Applications Ranging from Gravitational Wave Detection, High-Resolution Spectroscopy, and Optical Filters to Quantum Optomechanics. Integrated with Optical Fiber Waveguide Technology, the Fiber-Optic Fabry-Perot Interferometers Have Emerged as a Unique Candidate for High-Sensitivity Sensing and Have Undergone Tremendous Growth and Advancement in the Past Two Decades with their Successful Applications in an Expansive Range of Fields. the Extrinsic Cavity-Based Devices, I.e., the Fiber-Optic Extrinsic Fabry-Perot Interferometers (EFPIs), Enable Great Flexibility in the Design of the Sensitive Fabry-Perot Cavity Combined with State-Of-The-Art Micromachining and Conventional Mechanical Fabrication, Leading to the Development of a Diverse Array of EFPI Sensors Targeting at Different Physical Quantities. Here, We Summarize the Recent Progress of Fiber-Optic EFPI Sensors, Providing an overview of Different Physical and Mechanical Sensors based on the Fabry-Perot Interferometer Principle, with a Special Focus on Displacement-Related Quantities, Such as Strain, Force, Tilt, Vibration and Acceleration, Pressure, and Acoustic. the Working Principle and Signal Demodulation Methods Are Shown in Brief. Perspectives on Further Advancement of EFPI Sensing Technologies Are Also Discussed
Ultra-wide detuning planar Bragg grating fabrication technique based on direct UV grating writing with electro-optic phase modulation
A direct UV grating writing technique based on phase-controlled interferometry is proposed and demonstrated in a silica-on-silicon platform, with a wider wavelength detuning range than any previously reported UV writing technology. Electro-optic phase modulation of one beam in the interferometer is used to manipulate the fringe pattern and thus control the parameters of the Bragg gratings and waveguides. Various grating structures with refractive index apodization, phase shifts and index contrasts of up to 0.8×10-3 have been demonstrated. The method offers significant time/energy efficiency as well as simplified optical layout and fabrication process. We have shown Bragg gratings can be made from 1200 nm to 1900 nm exclusively under software control and the maximum peak grating reflectivity only decreases by 3dB over a 250 nm (~32THz) bandwidth
Fiber optic control system integration
A total fiber optic, integrated propulsion/flight control system concept for advanced fighter aircraft is presented. Fiber optic technology pertaining to this system is identified and evaluated for application readiness. A fiber optic sensor vendor survey was completed, and the results are reported. The advantages of centralized/direct architecture are reviewed, and the concept of the protocol branch is explained. Preliminary protocol branch selections are made based on the F-18/F404 application. Concepts for new optical tools are described. Development plans for the optical technology and the described system are included
Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology
INE/AUTC 10.0
Characterization and Testing of a Micro-g Whispering Gallery Mode Optomechanical Accelerometer
Navigation, bio-tracking devices and gravity gradiometry are amongst the
diverse range of applications requiring ultrasensitive measurements of
acceleration. We describe an accelerometer that exploits the dispersive and
dissipative coupling of the motion of an optical whispering gallery mode (WGM)
resonator to a waveguide. A silica microsphere-cantilever is used as both the
optical cavity and inertial test-mass. Deflections of the cantilever in
response to acceleration alter the evanescent coupling between the microsphere
and the waveguide, in turn causing a measurable frequency shift and broadening
of the WGM resonance. The theory of this optomechanical response is outlined.
By extracting the dispersive and dissipative optomechanical rates from data we
find good agreement between our model and sensor response. A noise density of
4.5 g Hz with a bias instability of 31.8 g (g=9.81
ms) is measured, limited by classical noise larger than the test-mass
thermal motion. Closed-loop feedback is demonstrated to reduce the bias
instability and long term drift. Currently this sensor outperforms both
commercial accelerometers used for navigation and those in ballistocardiology
for monitoring blood flowing into the heart. Further optimization would enable
short-range gravitational force detection with operation beyond the lab for
terrestrial or space gradiometry.Comment: 8 pages, 9 figures. Minor changes: additional methodology for
calculating noise terms with recalculation of acceleration random walk and
rate ramp. Gradient guide-lines and arrows on Figure 7(a) corrected, no
change to dat
Optical waveguide sensors
An overview of the field of optical waveguide sensors is presented. Some emphasis is laid on the development of a single scheme under which the diversity of sensor principles can be arranged. First three types of sensors are distinguished: intrinsic, extrinsic and active. Next, two steps are distinguished in the sensing process: the physical alteration of the waveguide (via geometrical and/or materials effects) and the effect thereof on the guided light (changing phase and/or amplitude of the light modes). The diversity and common features of the field of optical waveguide sensors are demonstrated with the help of many examples.\ud
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