Birefringent-fiber polarization coupler

Youngquist, Robert C.; Brooks, J. L.; Shaw, H. J.

doi:10.1364/ol.8.000656

Cited by 41 publications

(18 citation statements)

References 8 publications

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“…In a fibre of total length 1, a modal coupler [4,5] placed at a length L from the output causes power coupling between the modes, so that the power initially propagating in just one mode, propagates in two modes beyond the coupling point. The time t 1 , taken for light in path or mode (a) to reach the end of the fibre, a distance L1 from the coupling point, is given by…”

Section: Operating Principlesmentioning

confidence: 99%

An Extended Fibre Optic Stress Location Sensor

Franks

Torruellas

Youngquist

1986

Optica Acta: International Journal of Optics

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A new type of stress location sensor is discussed, in which the frequency-modulated continuous wave (FMCW) technique is used to detect the difference in propagation time between two optical paths in an optical fibre interferometer. The interferometer is formed by the polarization modes in a birefringent fibre, and the location of stress experienced by the fibre may be measured to within + 1-2 m. A variation of the interferometer using the LPo 0 1 and LPll mode-sets in a step-index fibre is investigated, and it is found that dispersion within the LP,, mode-set limits the accuracy of the system.

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Section: Operating Principlesmentioning

confidence: 99%

An Extended Fibre Optic Stress Location Sensor

Franks

Torruellas

Youngquist

1986

Optica Acta: International Journal of Optics

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“…The As 2 Se 3 fiber was placed in between an aluminum plate and a 50 mm long threaded steel rod with a period length of 0.7 mm and a groove depth of 0.4 mm. The rod was pressed onto the fiber inducing a periodic refractive index modulation along the fiber due to a combination of the photelastic effect [6] and induced microbends [7]. We used a single-mode As 2 Se 3 chalcogenide glass fiber with a core diameter of 6 μm, a core/cladding refractive index of 2.7, and a numerical aperture at 1550 nm of 0.18 [8].…”

Section: Introductionmentioning

confidence: 99%

Long-period grating in chalcogenide fibers: Application to monitoring photobleaching

Pudo

Mägi

Eggleton

2006

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference

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We report the first demonstration of long period gratings in single mode As 2 Se 3 chalcogenide glass fiber. The grating is subsequently used to detect what we believe is a weak, reversible photobleaching process.Introduction: Chalcogenide glass based optical fibers are an excellent candidate for all-optical signal processing due to their large Kerr nonlinearity (up to 1000 x silica glass [1]), low two-photon absorption, and an intrinsic response time below 100 fs [1]. However, chalcogenide glasses are known to exhibit a large array of photoinduced effects, either structural (e.g., photoexpansion), or optical (e.g., photodarkening, photobleaching) [2].While most studies have been carried out on thin film or bulk samples [3], a more thorough characterization and understanding of the dynamics of these effects in fibers is in order to properly design future high-speed nonlinear devices based upon chalcogenide glasses. Photobleaching manifests in a shift in the absorption band, thereby lowering the glass refractive index. In order to detect it in a fiber, a particularly elegant way is to monitor the resonance spectrum of a long-period grating (LPG) incorporated into the chalcogenide fibre, which is inherently a very sensitive structure to small refractive index variations [4]. Moreover, the LPG transparency outside the resonant band allows the monitoring of the photo-induced effects without interfering with the process, while the reversibility of mechanicallyinduced gratings keeps the fiber unaltered.In this paper, we demonstrate resonant coupling in single-mode chalcogenide LPGs. We describe the grating design, characterizing its transmission, polarization dependence, and thermal sensitivity. We subsequently use the grating as a simple sensor to detect small refractive index changes associated with photobleaching in the chalcogenide fiber induced by exposure to Watt-level picosecond pulses at 1.5 μm.

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“…The method of temporary alteration has the advantage of dynamically controlling the function of spectral filtering. Dynamic long-period fiber gratings can be implemented through the application of either an acoustic wave [4]- [7], or periodical loading onto fiber [8]- [lO]. In either technique, two possible mechanisms may result in the aforementioned phase matching process, including geometric deformation (micro-bending) and elastooptical effect for periodical refractive index variation of the fiber.…”

Section: Introductionmentioning

confidence: 99%

<title>Flexural waves on fiber and fiber Bragg gratings for WDM switching and gain equalization of erbium-doped fiber amplifiers</title>

et al. 2001

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Flexural waves on fiber and fiber Bragg gratings generated with applied ultrasounds and loading were used for switching the reflection wavelength of fiber Bragg grating and for controlling the transmission spectra of fiber. By producing lateral vibration of a fiber Bragg grating, which has been etched in cladding, it was found that the reflection wavelength could be switched from the Bragg wavelength to other wavelengths, which corresponded to the conditions of strong coupling between core mode and cladding modes. By adjusting the applied voltage for acoustic waves, the relative strength of different reflection wavelengths could be well adjusted. Theoretical analysis of phase-matching condition indicated that the diameter of etched cladding played a key role in controlling the switched reflection wavelength. Flexural waves were also generated on fiber by applying loading with one or two periodically corrugated plates. By adjusting the orientation of the periodical corrugation, loading level, and the relative position of the two corrugated plates, depressions of transmission spectrum at various wavelengths could be well controlled. The spectral depressions were caused by the coupling between core mode and various cladding modes. Such depressions were used for gain equalization oferbium-doped fiber amplifiers. The equalization operation was more efficient with curved fiber under loading. Control of fiber curvature for various forms of spectral depression will be discussed.

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Birefringent-fiber polarization coupler

Cited by 41 publications

References 8 publications

An Extended Fibre Optic Stress Location Sensor

An Extended Fibre Optic Stress Location Sensor

Long-period grating in chalcogenide fibers: Application to monitoring photobleaching

<title>Flexural waves on fiber and fiber Bragg gratings for WDM switching and gain equalization of erbium-doped fiber amplifiers</title>

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