Mode coupling and phase modulation in vibrating waveguides

Kajenski, Peter J.; Fuhr, Peter L.; Huston, Dryver R.

doi:10.1109/50.156882

Cited by 33 publications

(27 citation statements)

References 10 publications

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“…The speckle patterns could be reduced by the phase modulation when the waveguide is vibrated [6]. Based on this effect in addition to fiber bending, Kajenski et al found that the speckle patterns can be affected by mode coupling and phase modulation simultaneously and that modulation of speckle is dominated by the phase modulation when a highly coherent source is used [7]. Although vibrating the fiber has been found to be a fruitful method, Kajenski's model had a weak point in that their system was not compatible with integrated optical circuits.…”

Section: Introductionmentioning

confidence: 99%

Speckle Reduction in Near-field Image of Multimode Fiber with a Piezoelectric Transducer

Ha¹,

Lee²,

Oh³

et al. 2008

Journal of the Optical Society of Korea

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We propose and experimentally demonstrate an effective method to reduce near-field speckle noise at the output of a 50 μm graded index multimode fiber using a short cylindrical piezoelectric transducer (PZT) vibrating in the radial direction. The fiber was coiled as tightly as possible around the mandrel of the PZT and a periodic stretching effect was caused by the radial oscillations of the actuator. The output of the optical fiber using the He-Ne laser source was intensively observed by a CCD camera. By counting all the pixels corresponding to relative intensity graded into 256 levels in the selected area and by calculating standard deviation and mean value of the intensity, we could measure the speckle contrast and vibration effect quantitatively with reduction ratio of pixels and line profile of the illuminated region. It was clearly observed that the characteristics of the speckle pattern in the vibration-on state were significantly improved over that of the vibration-off state due to time-averaged smoothing.

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Section: Introductionmentioning

confidence: 99%

Speckle Reduction in Near-field Image of Multimode Fiber with a Piezoelectric Transducer

Ha¹,

Lee²,

Oh³

et al. 2008

Journal of the Optical Society of Korea

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show abstract

“…If h mn becomes larger in a random manner by external perturbations, the average power of the speckle regions increases [4] and the contrast decreases, which results in a more uniform fiber output. Therefore, we derive the relation between h mn and experimental parameters to find optimal conditions of homogenization, but thorough calculation of Eq.…”

Section: Theorymentioning

confidence: 99%

“…When an optical waveguide is externally disturbed, the distribution of light in the output pattern is modulated due to phase modulation and mode coupling of the guided modes [4]. Various analyses have been performed for phase modulation [1,4,8], and the main conclusion for effective smoothing of the spatial modes was that the relative carrier phase should be varied by more than 2π radian on a time scale faster than the response time of the detecting system.…”

Section: Theorymentioning

confidence: 99%

“…Various analyses have been performed for phase modulation [1,4,8], and the main conclusion for effective smoothing of the spatial modes was that the relative carrier phase should be varied by more than 2π radian on a time scale faster than the response time of the detecting system.…”

Section: Theorymentioning

confidence: 99%

“…To circumvent a high-cost and complex structure system, vibration techniques have been introduced that utilize both mode coupling and phase modulation [3,4]. However, to practically reduce the speckle contrast in such cases, longer exposure time and post-processing were required for effective ensemble averaging of uncorrelated patterns on an irradiance basis.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Acousto-optic control of speckle contrast in multimode fibers with a cylindrical piezoelectric transducer oscillating in the radial direction

Ha¹,

Lee²,

Jung³

et al. 2009

Opt. Express

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Abstract:We report efficient acousto-optic control of speckle contrast at the output of multimode fibers (MMFs) using a cylindrical piezoelectric transducer (PZT) vibrating in the radial direction. With appropriate packaging of an MMF around the PZT, periodic stretching and subsequent intensity modulation were achieved over the wound fiber to result in timeaveraged smoothing of the output within a short time. It was experimentally confirmed that light passed through the vibrating PZT-fiber assembly maintains the virtually partial coherence irrespective of the guide length and power splitting. Real-time vibration-off/on movies were presented, and their single-frame excerpts were analyzed. Electron. Lett. 15(23), 755-756 (1979). 13. E. G. Rawson, J. W. Goodman, and R. E. Norton, "Analysis and measurement of the modal-noise probability distribution for a step-index optical fiber," Opt. Lett. 5(8), 357-358 (1980). 14. D. U. Kim, S. C. Bae, J. Kim, T.-Y. Kim, C.-S. Park, and K. Oh, "Hard polymer cladding fiber (HPCF) links for high-speed short reach 1×4 passive optical network (PON) based on all-HPCF compatible fused taper power splitter," IEEE Photon. ©2009 Optical Society of America

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Performance enhancement on mechanical and electrical effects for on-line fiber-optic bending loss measurement

Cheng

Tsao

2005

Optik

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Mode coupling and phase modulation in vibrating waveguides

Cited by 33 publications

References 10 publications

Speckle Reduction in Near-field Image of Multimode Fiber with a Piezoelectric Transducer

Speckle Reduction in Near-field Image of Multimode Fiber with a Piezoelectric Transducer

Acousto-optic control of speckle contrast in multimode fibers with a cylindrical piezoelectric transducer oscillating in the radial direction

Performance enhancement on mechanical and electrical effects for on-line fiber-optic bending loss measurement

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