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Showing papers on "Dispersion-shifted fiber published in 1997"


Journal ArticleDOI
TL;DR: An effective-index model confirms that an all-silica optical fiber made by embedding a central core in a two-dimensional photonic crystal with a micrometer-spaced hexagonal array of air holes can be single mode for any wavelength.
Abstract: We made an all-silica optical fiber by embedding a central core in a two-dimensional photonic crystal with a micrometer-spaced hexagonal array of air holes. An effective-index model confirms that such a fiber can be single mode for any wavelength. Its useful single-mode range within the transparency window of silica, although wide, is ultimately bounded by a bend-loss edge at short wavelengths as well as at long wavelengths.

2,905 citations


Journal ArticleDOI
TL;DR: A theoretical model indicates that this mode of operation can be explained by the internal birefringence of the laser cavity combined with a nonlinear transmission element and the gain response of the fiber amplifier.
Abstract: An erbium-doped fiber laser that produces a train of intense noiselike pulses with a broadband spectrum and a short coherence length is reported. The noiselike behavior was observed in the amplitude as well as in the phase of the pulses. The maximum spectral width obtained was 44 nm. The high intensity and the short coherence length of the light were maintained even after propagation through a long dispersive fiber. A theoretical model indicates that this mode of operation can be explained by the internal birefringence of the laser cavity combined with a nonlinear transmission element and the gain response of the fiber amplifier.

457 citations


Journal ArticleDOI
TL;DR: A new mechanism for passive Q switching of fiber lasers is discovered and 10-kW peak power pulses with ~2-ns pulse widths are reported from a diode-pumped ytterbium-doped fiber laser.
Abstract: We have discovered a new mechanism for passive Q switching of fiber lasers. 10-kW peak power pulses with ∼2-ns pulse widths are reported from a diode-pumped ytterbium-doped fiber laser. The laser generates a high-brightness Raman-dominated supercontinuum spectrum covering the complete window of transparency of silica fiber in the infrared from 1.06 to 2.3 µm

282 citations


Journal ArticleDOI
TL;DR: In this article, a review of the research progress of nonlinear optical properties of Chalcogenide glass fiber and its application to all-optical switching is presented, where specific linear and nonlinear properties of the fiber are summarized.

256 citations


Journal ArticleDOI
TL;DR: In this article, a silica-based erbium doped fiber amplifier (EDFA) with a flat gain bandwidth exceeding 40 nm is described, and the dual-stage EDFA includes a precisely designed inter-stage long-period fiber grating filter with more than 14dB peak attenuation.
Abstract: Broad-bandwidth amplification is essential for the construction of high-capacity multichannel communication systems. We describe a silica-based erbium doped fiber amplifier (EDFA) with a flat gain bandwidth exceeding 40 nm. The dual-stage EDFA includes a precisely designed inter-stage long-period fiber grating filter with more than 14-dB peak attenuation. By careful choice of the filter spectrum and fiber lengths, this EDFA is flat to within 1 dB over 40 nm while producing a noise figure below 4.0 dB and nearly +15-dBm output power.

248 citations


Patent
28 Jan 1997
TL;DR: In this article, the nonlinear frequency conversion of a nonlinear fiber amplifier at a signal wavelength (SW) was used to generate femtosecond pulses from laser amplifiers.
Abstract: An apparatus generates femtosecond pulses from laser amplifiers by nonlinear frequency conversion. The implementation of nonlinear frequency-conversion allows the design of highly nonlinear amplifiers at a signal wavelength (SW), while still preserving a high-quality pulse at an approximately frequency-doubled wavelength (FDW). Nonlinear frequency-conversion also allows for limited wavelength tuning of the FDW. As an example, the output from a nonlinear fiber amplifier is frequency-converted. By controlling the polarization state in the nonlinear fiber amplifier and by operating in the soliton-supporting dispersion regime of the host glass, an efficient nonlinear pulse compression for the SW is obtained. The generated pulse width is optimized by utilizing soliton compression in the presence of the Raman-self-frequency shift in the nonlinear fiber amplifier at the SW. High-power pulses are obtained by employing fiber amplifiers with large core-diameters. The efficiency of the nonlinear fiber amplifier is optimized by using a double clad fiber (i.e., a fiber with a double-step refractive index profile) and by pumping light directly into the inner core of this fiber. Periodically poled LiNbO3 (PPLN) is used for efficient conversion of the SW to a FDW. The quality of the pulses at the FDW can further be improved by nonlinear frequency conversion of the compressed and Raman-shifted signal pulses at the SW. The use of Raman-shifting further increases the tuning range at the FDW. For applications in confocal microscopy, a special linear fiber amplifier is used.

236 citations


Patent
25 Jun 1997
TL;DR: In this paper, a singlemode is launched into a multi-mode (MM) optical fiber by matching the modal profile of the fundamental mode of the MM fiber with a diffraction-limited optical mode at the launch end.
Abstract: To amplify and compress optical pulses in a multi-mode (MM) optical fiber, a single-mode is launched into the MM fiber by matching the modal profile of the fundamental mode of the MM fiber with a diffraction-limited optical mode at the launch end. The fundamental mode is preserved in the MM fiber by minimizing mode-coupling by using relatively short lengths of step-index MM fibers with a few hundred modes and by minimizing fiber perturbations. Doping is confined to the center of the fiber core to preferentially amplify the fundamental mode, to reduce amplified spontaneous emission and to allow gain-guiding of the fundamental mode. Gain-guiding allows for the design of systems with length-dependent and power-dependent diameters of the fundamental mode. To allow pumping with high-power laser diodes, a double-clad amplifier structure is employed. For applications in nonlinear pulse-compression, self phase modulation and dispersion in the optical fibers can be exploited. High-power optical pulses may be linearly compressed using bulk optics dispersive delay lines or by chirped fiber Bragg gratings written directly into the SM or MM optical fiber. High-power cw lasers operating in a single near-diffraction-limited mode may be constructed from MM fibers by incorporating effective mode-filters into the laser cavity. Regenerative fiber amplifiers may be constructed from MM fibers by careful control of the recirculating mode. Higher-power Q-switched fiber lasers may be constructed by exploiting the large energy stored in MM fiber amplifiers.

231 citations


Patent
21 Feb 1997
TL;DR: In this article, a system-level optical measurement probe would include a laser, a spectrometer, a first optical fiber to carry energy from the laser to a sample, including a Bragg grating laser bandpass filter at its tip, and a second optical fiber, which would have included within it at its distal tip an optical filter to selectively reject energy associated with the nominal wavelength.
Abstract: Laser band-pass filter and/or band-reject filters are located at the end of an optical measurement probe by placing an appropriate Bragg grating proximate to the tip, and within, one or both of the optical fibers that make up the probehead. Thus, where an optical fiber is used to carry excitation energy of a nominal wavelength to a sample, the distal tip of this fiber will have included therein an optical filter to selectively pass energy of the nominal wavelength. Similarly, where an optical fiber is employed to carry stimulated emission from the sample to an analytical instrument such as a spectrometer, this fiber will have included within it at its distal tip an optical filter to selectively reject energy associated with the nominal wavelength. A disclosed system-level optical measurement probe would include a laser, a spectrometer, a first optical fiber to carry energy from the laser to a sample, including a Bragg grating laser bandpass filter at its tip, and a second optical fiber to carry energy collected from the sample to the spectrometer, including a Bragg grating laser band-reject filter at its tip.

214 citations


Patent
29 Dec 1997
TL;DR: In this paper, a dispersion-shifted fiber with a structure for effectively lowering polarization-mode dispersion was proposed, which is a singlemode optical fiber mainly composed of silica glass and has a zero-dispersion wavelength set within the range of at least 1.4 µm but not longer than 1.7 µm.
Abstract: The present invention relates to a dispersion-shifted fiber having a structure for effectively lowering polarization-mode dispersion. This dispersion-shifted fiber is a single-mode optical fiber mainly composed of silica glass and has a zero-dispersion wavelength set within the range of at least 1.4 µm but not longer than 1.7 µm. In particular, at least the whole core region of the dispersion-shifted fiber contains fluorine.

161 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a detailed discussion of the operation of hybrid Brillouin/erbium fiber laser (BEFL) for single and multiple wavelength generation and modeling of single wavelength operation.
Abstract: Brillouin/erbium fiber lasers (BEFLs) have been recently demonstrated as a novel mode of operation of a fiber laser. In a hybrid Brillouin/erbium fiber laser, the combination of two gain media, the gain from the erbium-doped fiber (EDF) and Brillouin gain in single-mode optical fibers allows a resonator to be constructed which supports a laser comb with /spl sim/10 GHz or /spl sim/0.1 nm line spacing at room temperature. In this paper, we present a detailed discussion of the operation of BEFLs. Single and multiple wavelength generation is discussed, and modeling of single wavelength operation is described.

109 citations


Patent
14 Apr 1997
TL;DR: In this article, a dispersion-compensating fiber for improving a transmission system with it in total chromatic dispersion and dispersion slope in the 1.55 µm wavelength band is presented.
Abstract: The present invention relates to a dispersion-compensating fiber for improving a transmission system with it in total chromatic dispersion and dispersion slope in the 1.55 µm wavelength band. The dispersion compensating fiber according to the present invention is characterized by having the following characteristics for light in the 1.55 µm wavelength band: chromatic dispersion preferably not less than -40 ps/km/nm and not more than 0 ps/km/nm; dispersion slope not less than -0.5 ps/km/nm2 and not more than -0.1 ps/km/nm2; transmission loss not more than 0.5 dB/km; polarization mode dispersion not more than 0.7 ps.cndot.km-1/2; cut-off wavelength not lees than 0.7 µm and not more than 1.7 µm in the length of 2 m; and bending loss at a diameter of 20 mm, not more than 100 dB/m. The dispersion-compensating fiber is optically connected at a ratio of appropriate lengths with a dispersion-shifted fiber as a compensated object; which can improve a system including the dispersion-compensating fiber in a total chromatic dispersion and dispersion slope of the system in the 1.55 µm band.

Journal ArticleDOI
TL;DR: In this article, a new type of underwater acoustic sensor with an optical fiber Bragg grating (FBG) is proposed, which is able to operate with much larger dynamic range both at higher and lower pressure levels.
Abstract: A new type of underwater acoustic sensor is proposed with an optical fiber Bragg grating (FBG). Because of the photoelasticity with respect to the refractive index and the elasticity of the fiber, the sound pressure in water modulates the Bragg reflection wavelength and, in turn, the intensity of the laser light transmitted through the FBG fiber. Good linearity between the detected signal and the sound pressure is obtained in the range from 81 dB to 140 dB re 1 μPa. Since the upper and lower limits of the acoustic signal level for operation of the sensor are limited by the driving circuit and the transduction of the sound in water, the sensor is expected to operate with much larger dynamic range both at higher and lower pressure levels. Operation of the sensor is very stable with the insertion of optical isolators into the system, although without the isolators the output signal fluctuates at low frequency due to the Fabry-Perot interference effect between the FBG and the various facets.

Journal ArticleDOI
TL;DR: Nonlinear pulse propagation in long-period fiber gratings is studied with a mode-locked Q -switched laser pulse approximately 80ps in duration at a wavelength of 1.05 microm.
Abstract: Nonlinear pulse propagation in long-period fiber gratings is studied with a mode-locked Q-switched laser pulse approximately 80 ps in duration at a wavelength of 1.05 µm. Optical switching, pulse reshaping, and optical limiting are found at intensities in the range of 1–20 GW/cm2.

Journal ArticleDOI
TL;DR: In this article, the authors compare numerically long distance propagation of two types of nonlinear pulses: a stretched pulse in a fiber with alternating normal and anomalous dispersion and a soliton in a fibre with uniformly anomalous dispersal.
Abstract: We compare numerically long-distance propagation of two types of nonlinear pulses: a stretched pulse in a fiber with alternating normal and anomalous dispersion and a soliton in a fiber with uniformly anomalous dispersion. Numerical evaluation of timing jitter and Q factor reveals that stretched pulses can be propagated over longer distances than solitons with the same (averaged) fiber dispersion in the presence of weak fixed-frequency filtering. We also examine pulse-to-pulse interactions between stretched pulses and the influence of fluctuations of the fiber dispersion.

Journal ArticleDOI
TL;DR: What is to the authors' knowledge the first demonstration of pulse amplification in a cw-pumped fiber in which the doped gain medium has a ring shape surrounding a single-mode core is reported.
Abstract: We report what is to our knowledge the first demonstration of pulse amplification in a cw-pumped fiber in which the doped gain medium has a ring shape surrounding a single-mode core. For a given pump power, ring doping reduces the gain and hence the power lost to amplified spontaneous emission. Thereby, a significantly larger amount of energy can be stored in the amplifier. Using an Yb3+-doped fiber pumped by 540 mW of power at 1000 nm, we measured 69 µJ of extracted pulse energy at 1047 nm, the highest value reported to date from a single-mode Yb3+-doped fiber. We predict that a fiber cladding pumped by a diode bar can produce pulse energies in excess of 1 mJ.

Journal ArticleDOI
TL;DR: Pulse propagation in an optical fiber employing a periodic dispersion map is analyzed and second-order averaging is used to determine a general evolution equation valid for both return-to-zero and non-return- to-zero pulses in dispersion-managed systems.
Abstract: We analyze pulse propagation in an optical fiber employing a periodic dispersion map. Second-order averaging is used to determine a general evolution equation valid for both return-to-zero and non-return-to-zero pulses in dispersion-managed systems. The equation is then applied to the case of solitons, and an analytic expression for the power enhancement arising from the dispersion management is obtained.

Journal ArticleDOI
TL;DR: In this paper, design criteria for fiber grating filters in DWDM systems using both Gaussian pulses and super-Gaussian pulses that approximate square pulses that are more common in non-return-to-zero (NRZ) systems were considered.
Abstract: For high bit-rate dense wavelength-division multiplexed (DWDM) applications fiber grating dispersion for the transmitted adjacent channels is shown to be detrimental and ultimately leads to a penalty. We consider design criteria for fiber grating filters in DWDM systems using both Gaussian pulses and super-Gaussian pulses that approximate square pulses that are more common in nonreturn-to-zero (NRZ) systems.

Journal ArticleDOI
TL;DR: In this article, the effects of Parametric Gain (PG) in optical fibers on ASE noise and fiber dispersion in both anomalous and normal dispersion regions were investigated.
Abstract: Parametric gain (PG) in optical fibers may substantially enhance ASE noise, especially in long-haul amplified systems. We present new closed-form analytical results that permit to accurately characterize the effects of PG on ASE noise, as well as the interplay of PG and ASE noise with fiber dispersion in both the anomalous and normal dispersion regions. We introduce the concept of a PG transfer matrix that allows the easy analytical evaluation of ASE noise enhancement over chains of amplified fiber spans.

Patent
21 Feb 1997
TL;DR: In this article, a phase-shift is applied to the wave within each time cell in which the optical power is low and that precedes or follows a cell with high power.
Abstract: To increase the transmission length in an optical fiber, a method of transmitting digital data uses both power modulation and phase modulation of an optical carrier. To compensate the chromatic dispersion produced by the fiber, a phase-shift is applied to the wave within each time cell in which the optical power is low and that precedes or follows a cell in which the power is high. Applications include long-distance optical transmission using standard fibers.

Journal ArticleDOI
TL;DR: In this article, a fiber optic pH sensor based on evanescent wave absorption is presented, where a thin porous film of glass with pH-sensitive dye entrapped in it is deposited on the surface of the unclad portion of the fiber using sol-gel technology.

Patent
Yasushi Sugaya1
19 Feb 1997
TL;DR: In this article, a doped fiber amplifier which provides bidirectional pumping to amplify a signal light, and reduces the instability of gain caused by the bidding process is presented, and the amplifier includes a rare earth element doped optical fiber, a first light source and a second light source.
Abstract: A doped fiber amplifier which provides bidirectional pumping to amplify a signal light, and reduces instability of gain caused by the bidirectional pumping. The doped fiber amplifier includes a rare earth element doped optical fiber, a first light source and a second light source. The optical fiber has first and second ends, with the signal light propagating through the optical fiber from the first end to the second end. The first light source provides pump light which propagates in the optical fiber from the first end to the second end and is at a first wavelength. The second light source provides pump light which propagates in the optical fiber from the second end to the first end and is at a second wavelength. The first wavelength is different from the second wavelength. The pump light provided by the first and second light sources causes the signal light to be amplified as the signal light propagates through the optical fiber.

Journal ArticleDOI
TL;DR: In this article, a pigtailed erbium-ytterbium codoped planar glass waveguide amplifier module with a single 980-nm diode pump is presented.
Abstract: We report the full characterization of a pigtailed erbium-ytterbium codoped planar glass waveguide amplifier module. With a single 980-nm diode pump, this ion-exchanged 4.5-cm-long device delivers a signal gain of 16.5 dB, a noise figure of 5 dB, and a saturated output power of 12.5 dBm. To verify its practicality and stability, we tested this module as a power booster in a 10 Gb/s transmission system experiment at the 1534 nm wavelength, and demonstrated the successful bit-error-rate (BER<10/sup -12/) transmission over 72.5 km of dispersion shifted fiber.

Proceedings ArticleDOI
22 Sep 1997
TL;DR: In this article, a new type of network fiber which has reverse dispersion and dispersion slope against 13 μm zero dispersion SMF was designed and fabricated and the total dispersion was managed to be nearly zero and flat at 155 μm region by combining SMF with new fiber of approximately 1:1 length.
Abstract: New type of network fiber which has reverse dispersion and dispersion slope against 13 μm zero dispersion SMF was designed and fabricated The total dispersion was managed to be nearly zero and flat at 155 μm region by combining SMF with new fiber of approximately 1:1 length

Journal ArticleDOI
Michael J. Renn1, Alex Zozulya1, Elizabeth A. Donley1, Eric A. Cornell1, Dana Z. Anderson1 
TL;DR: In this paper, the flux of laser-guided atoms through hollow-core optical fibers is investigated and the authors show that the flux depends on laser detuning from resonance, laser intensity, and fiber curvature.
Abstract: We present an experimental and theoretical investigation characterizing the flux of laser-guided atoms through hollow-core optical fibers and show how it depends on laser detuning from resonance, laser intensity, and fiber curvature. The guiding employs dipole forces arising from the interaction of the atoms with the optical field. Laser light is focused into the hollow region of 40-\ensuremath{\mu}m-inner-diam capillary fiber and guided through the fiber by grazing incidence reflection from the glass walls. The lowest-order mode is azimuthally symmetric with maximum intensity on the fiber axis and nearly zero intensity at the walls. Rubidium atoms are attracted to the high-intensity region along the axis when the laser is detuned to the red of resonance and consequently guided through the fiber. Of particular interest is the evolution of the atom-flux versus laser-detuning profile of increasing intensity. At low intensities the dipole guiding potential is purely conservative and the flux profile is roughly dispersion shaped. At high intensity, viscous dipole forces heat the atoms and ``burn a hole'' in the flux-detuning curve. We find that transverse heating of the atoms and the exponential attenuation of optical mode intensity limit the distance atoms may be guided to about 20 cm in a 40-\ensuremath{\mu}m-diam fiber. Bending the fiber can reduce the effects of heating on atom flux.

Patent
27 May 1997
TL;DR: In this paper, the authors proposed an arrangement for coupling several energizing lasers to the active medium of an optical fiber light source, where a section of multimode fiber is interposed between an energizing laser (e.g., a diode laser) and a single mode fiber active medium.
Abstract: In an optical fiber light source a section of multimode fiber (51) is interposed between an energizing laser (e.g., a diode laser (49)) and a single mode fiber active medium (43). In a preferred embodiment the single mode fiber active medium is surrounded by a multimode cladding (45) coupled to the multimode fiber. The source may serve as a pump laser for a fiber amplifier (30) or as an amplified spontaneous emission source. Arrangements for coupling several energizing lasers to the active medium are also described.

Patent
03 Dec 1997
TL;DR: In this paper, a temperature compensating structure for a fiber Bragg grating (FBG) contained in optical fiber is proposed, which comprises two plates made of materials having different temperature coefficients of expansion and bonded together.
Abstract: The invention is a temperature compensating structure for a fiber Bragg grating (FBG) contained in optical fiber. The structure comprises two plates made of materials having different temperature coefficients of expansion and bonded together. The optical fiber is bonded to the exposed surface of the plate having the lower temperature coefficient. The structure bends with changes in temperature and produces an elongation of the fiber with decreasing temperature.

Proceedings ArticleDOI
Shigeki Watanabe1, S. Takeda1, George Ishikawa1, H. Ooi1, J.G. Nielsen1, Carsten Sonne1 
22 Sep 1997
TL;DR: In this paper, a four-wave mixing in a dispersion arranged 750m highly nonlinear dispersion-shifted fiber with a nonlinear coefficient of 20.4 W-1 km-1.
Abstract: A simultaneous wavelength conversion of 200 Gb/s (5×40 Gb/s) WDM signal over the entire gain band of an Er-doped fiber amplifier (EDFA) is demonstrated by a four-wave mixing in a dispersion arranged 750-m highly nonlinear dispersion-shifted fiber with a nonlinear coefficient of 20.4 W-1 km-1. Simultaneous optical phase conjugation is also demonstrated with successful dispersion compensation in a 200 Gb/s (5×40 Gb/s) WDM transmission through a 105 km conventional single-mode fiber.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrated the feasibility of achieving high performance fiber polarizers (insertion loss 30 dB), based on polarization mode dispersion in a long-period grating.
Abstract: We have demonstrated the feasibility of achieving high-performance fiber polarizers (insertion loss 30 dB), based on polarization mode dispersion in a long-period grating. Chirped operation with 100-nm bandwidth has also been achieved, showing the possibility of a broad-band device.

Journal ArticleDOI
TL;DR: In this article, a novel technique of using different lengths of optical fiber as strain sensors in a white-light interferometer to measure the strain distribution is presented, and the technique for connecting the fiber sensors and the method of calculating the intensity of the transmitted and reflected light are given.
Abstract: A novel technique of using different lengths of optical fiber as strain sensors in a white-light interferometer to measure the strain distribution is presented. The technique for connecting the fiber sensors and the method of calculating the intensity of the transmitted and reflected light are given. The measuring principle and a four-sensor distributed fiber-optic strain-measuring system are demonstrated. Calibration experiments results show that the relationship of the strain between the embedded fiber and the matrix is linear and the sensitivity of the fiber sensor is a function of the sensing length of the embedded fiber.

Journal ArticleDOI
TL;DR: In this article, the authors report on stable soliton propagation experiments in a fiber transmission system consisting of more than 90% normal dispersion fiber, which has a dispersion map much like that used in non-return-to-zero (NRZ) pulse transmission but with a path-average anomalous dispersion of +0.1 ps/nm-km.
Abstract: We report on stable soliton propagation experiments in a fiber transmission system consisting of more than 90% normal dispersion fiber. The transmission system has a dispersion map much like that used in nonreturn-to-zero (NRZ) pulse transmission but with a path-average anomalous dispersion of +0.1 ps/nm-km. A stable soliton pulse train at 8 GHz has been observed after 28 Mm of propagation in a 108-km recirculating fiber-optic loop. A significant enhancement in the average soliton power required for stable transmission in a dispersion map with alternating signs of dispersion is experimentally demonstrated for the first time. Theoretical modeling of our experiment is in good agreement with our findings.