Center for Photonics Technology

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https://hdl.handle.net/10919/24790
The Center for Photonics Technology at Virginia Tech is focused on innovation in fiber optics, fiber optic sensors, and biomedical and applied optics. With five faculty and over 30 students and research staff, CPT is a world leader in fiber optic sensor research.

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Browsing Center for Photonics Technology by Author "Gong, Jianmin"

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    Decoding The Spectra Of Low-Finesse Extrinsic Optical Fiber Fabry-Perot Interferometers
    Ma, Cheng; Dong, Bin; Gong, Jianmin; Wang, Anbo (Optical Society of America, 2011)
    A theoretical model is developed to address the fringe visibility and additional phase in the interference spectra of low-finesse extrinsic optical fiber excited Fabry-Perot interferometers. The model described in the paper applies to both single-mode and multimode fiber excitations; according to the theory, the fringe visibility and additional phase term are primarily determined by the working wavelength and angular power density distribution outputting from the excitation fiber, rather than based on spatial and temporal degree of coherence. Under certain approximations, the output interference intensity and the spatial power density distribution projected onto the fiber axis form a Fourier-transform pair, which potentially provides a tool for spatial density distribution analysis of fiber output. With excellent agreement with experiments, the theory presented in this paper leads to design guidelines for Fabry-Perot interferometric sensors and insightful physical understanding of such devices. (C) 2011 Optical Society of America
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    Method Of Multiple References For 3D Imaging with Fourier Transform Interferometry
    Lally, Evan M.; Gong, Jianmin; Wang, Anbo (Optical Society of America, 2010-03-01)
    This letter presents an improved phase referencing technique, called Method of Multiple References, for optical profilometry. Based on a lookup table, the method eliminates several major drawbacks of single-reference Fourier Transform Interferometry by enabling surface error correction for steep slopes and step discontinuities, and by allowing mapping of multiple discrete objects using a single image set. The algorithm is tested using a fiber optic coupler-based FTI system and shown to have RMS surface error less than 0.03mm. (C) 2010 Optical Society of America
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    ZrO2 Thin-Film-Based Sapphire Fiber Temperature Sensor
    Wang, Jiajun; Lally, Evan M.; Wang, Xiaoping; Gong, Jianmin; Pickrell, Gary R.; Wang, Anbo (Optical Society of America, 2012-10-01)
    A submicrometer-thick zirconium dioxide film was deposited on the tip of a polished C-plane sapphire fiber to fabricate a temperature sensor that can work to an extended temperature range. Zirconium dioxide was selected as the thin film material to fabricate the temperature sensor because it has relatively close thermal expansion to that of sapphire, but more importantly it does not react appreciably with sapphire up to 1800 degrees C. In order to study the properties of the deposited thin film, ZrO2 was also deposited on C-plane sapphire substrates and characterized by x-ray diffraction for phase analysis as well as by atomic force microscopy for analysis of surface morphology. Using low-coherence optical interferometry, the fabricated thin-film-based sapphire fiber sensor was tested in the lab up to 1200 C and calibrated from 200 degrees to 1000 degrees C. The temperature resolution is determined to be 5.8 degrees C when using an Ocean Optics USB4000 spectrometer to detect the reflection spectra from the ZrO2 thin-film temperature sensor. (C) 2012 Optical Society of America OCIS codes: 060.2370, 120.6780, 310.1620.