Showing papers on "Dispersion-shifted fiber published in 1996"
01 Jan 1996
475 citations
TL;DR: In this article, the formation of stable soliton-like pulses in optical fibres with a periodic dispersion map was examined, and it was found that increased energy is required to launch a pulse of given width compared to the equivalent uniform fibre with equal path-average dispersion.
Abstract: The authors examine the formation of stable soliton-like pulses in optical fibres with a periodic dispersion map. It is found that increased energy is required to launch a pulse of given width compared to the equivalent uniform fibre with equal path-average dispersion. The stable pulse shapes in dispersion managed systems are significantly different to the hyperbolic secant solitons found in uniform fibres.
402 citations
TL;DR: In this article, the authors demonstrated simultaneous continuous wave multiwavelength operation of an erbium-doped fiber laser using two types of recently developed in-fiber grating comb filters.
Abstract: Simultaneous continuous wave multiwavelength operation of an erbium-doped fiber laser has been demonstrated using two types of recently developed in-fiber grating comb filters. The lasing wavelengths and linewidths were determined by the comb filter, which was inserted in a ring cavity with a single inhomogeneously broadened gain medium.
345 citations
TL;DR: Gain of 10-18 dB is obtained as the signal wavelength was tuned over a 35-nm bandwidth near 1560 nm and the amplifier was operated near the fiber's zero-dispersion wavelength.
Abstract: The bandwidth of a single-pump fiber optical parametric amplifier is governed by the even orders of fiber dispersion at the pump wavelength. The amplifier can exhibit gain over a wide wavelength range when operated near the fiber's zero-dispersion wavelength. It can also be used for broadband wavelength conversion,with gain. We have experimentally obtained gain of 10-18 dB as the signal wavelength was tuned over a 35-nm bandwidth near 1560 nm.
329 citations
TL;DR: In this article, a new method was proposed to compensate exactly for both chromatic dispersion and self-phase modulation in a transmission fiber, where the light intensity changes due to fiber loss and amplifier gain.
Abstract: We propose a new method to compensate exactly for both chromatic dispersion and self-phase modulation in a transmission fiber, where the light intensity changes due to fiber loss and amplifier gain. This method utilizes optical phase conjugation (OPC). The pulse shape is precompensated before OPC by transmission through a fiber with large dispersion. A computer simulation demonstrates effective compensation for waveform distortion in a 40 Gb/s NRZ intensity-modulated light transmission.
258 citations
TL;DR: A novel hybrid Brillouin/erbium fiber laser that uses both BrillouIn gain in singlemode optical fiber and gain in erbium-doped fiber is proposed and demonstrated.
Abstract: We propose and demonstrate a novel hybrid Brillouin/erbium fiber laser that uses both Brillouin gain in single-mode optical fiber and gain in erbium-doped fiber. The lasing frequency was accurately determined by the Brillouin shift in single-mode optical fiber and was 10.35 GHz from the Brillouin pump. Large powers could be extracted because of incorporation of erbium-doped fiber in the laser resonator. An output power of 10 mW was measured at a wavelength of 1532 nm.
203 citations
TL;DR: In this paper, the authors describe techniques for cascading the Brillouin/erbium fiber laser to generate optical combs, and experimentally demonstrate optical comb generation in the 1550-nm region.
Abstract: Brillouin/erbium fiber lasers, which have recently been demonstrated, operate with a combination of Brillouin gain and gain in erbium-doped fiber. In this letter, we describe techniques for cascading the Brillouin/erbium fiber laser to generate optical combs, and experimentally demonstrate optical comb generation. Internal and external cascading techniques are demonstrated. The line spacing in the combs is approximately 10 GHz, with operation in the 1550-nm region.
202 citations
TL;DR: In this paper, simultaneous laser operation of three single-frequency modes from an inhomogeneously broadened Er-doped twincore fiber loop laser is reported, achieving equal output power of 390 /spl mu/W, separation 0.5 nm, and linewidth <10 kHz.
Abstract: Simultaneous laser operation of three single-frequency modes from an inhomogeneously broadened Er-doped twincore fiber loop laser is reported. Equal output power of 390 /spl mu/W, separation 0.5 nm, and linewidth <10 kHz were measured for each mode in a travelling wave cavity comprising a single gain medium. In addition up to eight wavelength operation has been observed, demonstrating that twincore EDFA's can provide channel equalization in an eight-channel multiamplifier optical network.
183 citations
TL;DR: In this paper, a novel dispersion compensating fiber design consisting of two highly asymmetric concentric cores was proposed, which can have very large negative dispersion values with larger mode field diameter.
Abstract: We propose a novel dispersion compensating fiber design consisting of two highly asymmetric concentric cores. We show that the fundamental mode of the proposed fiber can have very large negative dispersion values [/spl sim/-5100 ps/(nm.km)] with larger mode field diameter (/spl sim/8-9 /spl mu/m) relative to the existing dispersion compensating fibers.
166 citations
TL;DR: In this paper, the authors theoretically and experimentally investigated the cross-phase modulation (XPM) effect in optical fiber links with multiple optical amplifiers and dispersion compensators, and they showed that the XPM effect can be modeled as a phase modulator with inputs from the intensity of copropagating waves.
Abstract: We have theoretically and experimentally investigated the cross-phase modulation (XPM) effect in optical fiber links with multiple optical amplifiers and dispersion compensators. Our theory suggests that the XPM effect can be modeled as a phase modulator with inputs from the intensity of copropagating waves. The frequency response of the phase modulator corresponding to each copropagating wave depends on fiber dispersion, wavelength separation, and fiber length. The total XPM-induced phase shift is the integral of the phase shift contributions from all frequency components of copropagating waves. In nondispersive fibers, XPM is frequency-independent; in dispersive fibers, XPM's frequency response is approximately inversely proportional to the product of frequency, fiber dispersion, and wavelength separation. In an N-segment amplified link, the frequency response of XPM is increased N-fold, but only in very narrow frequency bands. In most other frequency bands, the amount of increase is limited and almost independent of N. However, in an N-segment amplified link with dispersion compensators, the frequency response of XPM is increased N-fold at all frequencies if the dispersion is compensated for within each fiber segment. Thus, the XPM-induced phase shift is smaller in systems employing lumped dispersion compensation than in systems employing distributed dispersion compensation.
158 citations
TL;DR: Nonlinear pulse evolution is studied for a fiber with normal dispersion (ND) and gain, and numerical simulations show that under certain conditions the pulse evolves into a parabolic shape, which has been shown to reduce optical wave breaking.
Abstract: Nonlinear pulse evolution is studied for a fiber with normal dispersion (ND) and gain. Numerical simulations show that under certain conditions the pulse evolves into a parabolic shape, which has been shown to reduce optical wave breaking. Much as with the square pulse that forms in passive fibers with ND, the interplay of ND and self-phase modulation creates a highly linear chirp, which can be efficiently compressed. Application to an amplifying fiber/grating (prism) pair pulse compressor is considered, with an experimental demonstration of compression from 350 to 77 fs at a gain of 18 dB in an erbium-doped fiber amplifier.
TL;DR: An empirical scaling law is presented that models the increased energy required for launching a soliton into an optical system with sections of both normal and anomalous dispersion fiber and shows that the inclusion of periodic attenuation and amplification can be handled as separate problems.
Abstract: We present an empirical scaling law that models the increased energy required for launching a soliton into an optical system with sections of both normal and anomalous dispersion fiber. It is shown that the inclusion of periodic attenuation and amplification can be handled as separate problems, provided that the interval between optical amplifiers is substantially different from the period of the dispersion map. These concepts are illustrated by reference to an example system comprising dispersion-shifted fiber combined with anomalous standard fiber.
TL;DR: In this article, the effect of second-order polarization dispersion builds up with chromatic dispersion and can induce a severe degradation of the transmission performance, while the standard deviation of the penalties can increase severalfold in the presence of chromatic disersion.
Patent•
15 Mar 1996TL;DR: In this article, an optical fiber amplifier with residual pump power was proposed to ensure stable operation of a pump light source and efficiently makes use of residual pump energy to achieve improvement in conversion efficiency.
Abstract: The invention provides an optical fiber amplifier which assures stable operation of a pump light source and efficiently makes use of residual pump power to achieve improvement in conversion efficiency. The optical fiber amplifier includes a rare earth doped fiber. Pump light from a pump light source is introduced into one end of the rare earth doped fiber by way of a first optical coupler, and residual pump light originating from the pump light and arriving at the other end of the rare earth doped fiber is applied to the other rare earth doped fiber amplifier or the loss compensation of a dispersion compensating fiber by Raman amplification.
TL;DR: It is shown that the propagation constant mismatch /spl Lambda//spl beta/ for a 2-pump fiber OPA can be well approximated by a fourth-order Chebyshev polynomial, by adjusting /spl omega//sub c/, near /spl Omega//sub 0/, and the pump spacing.
Abstract: Theory predicts that a two-pump fiber optical parametric amplifier or wavelength converter operated near the fiber zero-dispersion wavelength can exhibit a gain spectrum approximated by a Chebyshev polynomial of order 8. Under realistic conditions of pump spacing and fiber dispersion, very low-gain ripple can be obtained over a large bandwidth. For example, a dispersion-shifted fiber can provide a signal amplifier with a gain of 20 dB with 0.2-dB uniformity over a 45-nm bandwidth. Potential limitations are discussed.
TL;DR: The results indicate that even if the refractive-index distribution is tightly controlled, the bandwidth of the graded-index POP is dominated by the material dispersion when the required bit rate becomes larger than a few gigabits per second.
Abstract: The optimum refractive-index distribution of the high-bandwidth graded-index polymer optical fiber (POP) was clarified for the first time by consideration of both modal and material dispersions. The ultimate bandwidth achieved by the POP is investigated by a quantitative estimation of the material dispersion as well as the modal dispersion. The results indicate that even if the refractive-index distribution is tightly controlled, the bandwidth of the graded-index POP is dominated by the material dispersion when the required bit rate becomes larger than a few gigabits per second. It is also confirmed that the material dispersion strongly depends on the matrix polymer and that the use of a fluorinated polymer whose material dispersion [-0.078 ns/(nm km)] is lower than that of poly(methyl methacrylate) [-0.305 ns/(nm km)] allows for a 10-Gb/s signal transmission.
TL;DR: A dispersive medium with a negative nonlinear refractive-index coefficient is proposed as a way to compensate for the dispersion and the nonlinear effects resulting from pulse propagation in an optical fiber to allow for increased bit rates.
Abstract: We propose the use of a dispersive medium with a negative nonlinear refractive-index coefficient as a way to compensate for the dispersion and the nonlinear effects resulting from pulse propagation in an optical fiber. The undoing of pulse interaction might allow for increased bit rates.
TL;DR: Temperature sensing to as low as 80 K was demonstrated with 1.55-μm fiber Bragg gratings and the temperature sensitivity values are smaller than those at room temperature because of the nonlinearity of both the thermal expansion and the thermo-optic effect.
Abstract: Temperature sensing to as low as 80 K was demonstrated with 1.55-μm fiber Bragg gratings. The gratings were bonded on substrates to increase sensitivity, and a shift of the reflection wavelength was measured. The temperature sensitivity was 0.02 nm/K at 100 K when an aluminum substrate was used and 0.04 nm/K at 100 K when a poly(methyl methacrylate) substrate was used. These values are smaller than those at room temperature because of the nonlinearity of both the thermal expansion and the thermo-optic effect. Extension to the liquid helium temperature is also discussed.
TL;DR: In this paper, a 1 Tb/s aggregate capacity (50 channels each at 20 Gb/S) was transmitted through 55 km of nonzero-dispersion fiber, where 50 channels were generated by polarization multiplexing 25 wavelengths.
Abstract: A 1-Tb/s aggregate capacity (50 channels each at 20 Gb/s) was transmitted through 55 km of nonzero-dispersion fiber. Fifty channels were generated by polarization multiplexing 25 wavelengths.
TL;DR: In this paper, a novel add/drop filter for use in WDM optical fiber systems based on a Bragg grating assisted mismatched coupler is presented. But it is not interferometric, unlike all similar devices demonstrated so far, and therefore does not need fine tuning of the interferometers during fabrication and does not have to maintain the balance of the interferer during its lifetime.
Abstract: We have demonstrated a novel add/drop filter for use in wavelength-division-multiplexing (WDM) optical fiber systems based on a Bragg grating assisted mismatched coupler. The device is potentially easy to fabricate and stable, because it is not interferometric, unlike all similar devices demonstrated so far, and, therefore, does not need fine tuning of the interferometers during fabrication and does not have to maintain the balance of the interferometers during its lifetime.
TL;DR: In this paper, a step-index polymer optical fiber doped with laser dyes has been fabricated and shown to achieve high gain and high efficiency optical amplification with a low pump power of less 1 kW and pulse width 5 ns.
Abstract: We report the development of a novel and simple technique for fabricating polymer optical fibers of good optical quality for special device applications. This technique aims at polymer fibers doped with various functional organic materials. On the basis of the technique, step-index polymer optical fibers doped with laser dyes have been fabricated. High-gain and high-efficiency optical amplification has been achieved in a Rhodamine B-doped polymer fiber with a low pump power of less 1 kW and pulse width 5 ns. Because a high dye concentration is used, the optimal wavelength range of optical amplification in this fiber is significantly red-shifted toward the center of the communication window (at 650 nm wavelength) of methyl methacrylate-based polymer optical fiber. The shift is from the originally 560 and 590 nm to presently 610 to 640 nm. We also present experimental results that show good photostability of the Rhodamine B-doped polymer fiber, compared with those recently reported in the improved polymer material systems. From the experimental observation, we identified the thermally induced bleach of dye molecules as the major contributing factor to the lifetime of our material system.
Patent•
04 Dec 1996
TL;DR: In this paper, a method and apparatus for managing dispersion in a WDM optical transmission system so that transmission performance is improved is presented, where the usable optical bandwidth of the transmission system is divided into sub-bands that individually undergo dispersion compensation before being re-combined.
Abstract: A method and apparatus is provided for managing dispersion in a WDM optical transmission system so that transmission performance is improved. The usable optical bandwidth of the transmission system is divided into sub-bands that individually undergo dispersion compensation before being re-combined. Accordingly, in comparison to known dispersion mapping techniques, more WDM data channels reside near a wavelength corresponding to the average zero dispersion wavelength.
TL;DR: In this paper, a method based on the phase mismatch of four-wave mixing was proposed for direct and accurate measurement of the dispersion map, D(λ, z), of an optical fiber.
Abstract: We describe a method, based on the phase mismatch of four-wave mixing, for direct and accurate measurement of the dispersion map, D(λ, z), of an optical fiber. The method, which requires no wavelength scanning and access to only one end of the fiber, has produced the data for an entire 34-km span, including hundreds of repetitions for signal averaging, in less than 0.25 s. Spatial resolution and accuracy in that first experimental test were ~1 km and δD ~ ±0.03 ps/(nm km), respectively.
TL;DR: In this paper, an average signal gain of 26 dB was achieved for 8-channel WDM signals in the 1532-1560 nm wavelength region with a gain excursion of less than 1.5 dB at an input signal power of -20 dBm per channel.
Abstract: We successfully developed a fluoride-based Er/sup 3+/-doped fiber amplifier (F-EDFA). An average signal gain of 26 dB was achieved for 8 channel wavelength division multiplexed (WDM) signals in the 1532-1560 nm wavelength region with a gain excursion of less than 1.5 dB at an input signal power of -20 dBm per channel. Furthermore, we studied the amplification characteristics of the F-EDFA for WDM signals. The following experimental results were obtained. (1) For an 8-channel WDM signal in the 1532 to 1560 nm wavelength region, the gain excursion between channels can be suppressed to within 1.5 dB. However, the wavelength region allowing a gain excursion of 1.5 dB, is between 1536-1560 nm for the silica-based Er/sup 3+/-doped fiber amplifier. (2) F-EDFAs have a flat gain region between 1534-1542 nm. The gain excursion of this region is less than 0.2 dB for WDM signals.
TL;DR: In this article, the authors report results of a system trial involving dispersion compensating chirped fiber gratings, demonstrating that transmission up to 537 km of standard telecommunications fiber is now feasible at 10 Gb/s, with a pair of 10-cm-long gratings cascaded together.
Abstract: We report on results of a system trial involving dispersion compensating chirped fiber gratings, demonstrating that transmission up to 537 km of standard telecommunications fiber is now feasible at 10 Gb/s, with a pair of 10-cm-long gratings cascaded together.
Patent•
JDSU1
TL;DR: In this paper, the optical circulator, a plurality of bandpass wavelength division units and fiber Bragg gratings arranged in the optical fibers interconnecting the optical circuit and the bandpass division units are described.
Abstract: Multiplexer and demultiplexer devices for Dense WDM networks are described. The devices use an optical circulator, a plurality of bandpass wavelength division units and fiber Bragg gratings arranged in the optical fibers interconnecting the optical circulator and the bandpass wavelength division units. The optical circulator is connected to a network optical fiber and the bandpass wavelength division units are connected to a plurality of input/output optical fibers. Each fiber Bragg grating has a narrow wavelength reflection band about a predetermined wavelength and is arranged so that optical signals at wavelengths differing from predetermined wavelengths of the first optical fibers connected to a bandpass wavelength division unit are blocked and reflected. Depending upon the direction of the optical circulator, the device may be a multiplexer or a demultiplexer. Alternatively, a 3dB optical coupler may be used in place of the optical circulator with a corresponding rearrangement of the fiber Bragg gratings.
TL;DR: Numerical simulation shows that this growth in four-wave mixing fields from soliton-soliton collisions can be eliminated through the use of fiber whose dispersion is tapered, either continuously or in steps, in conformity with the fiber loss curve.
Abstract: In a soliton transmission system using lumped amplifiers, pseudo phase matching allows four-wave mixing fields from soliton–soliton collisions to grow uncontrollably and inflict severe penalties. Through numerical simulation, we show that this growth can be eliminated, or at least greatly reduced, through the use of fiber whose dispersion is tapered, either continuously or in steps, in conformity with the fiber loss curve.
Patent•
12 Feb 1996TL;DR: In this article, a low-noise optical fiber Raman amplifier (FRA) is proposed for optical fiber communication systems, which can serve as power amplifier, as pre-amplifier, or as in-line amplifier.
Abstract: A low noise optical fiber Raman amplifier (FRA) comprises an upstream and a downstream length of silica-based amplifier fiber, of combined length >200 m, typically >1 km, with an optical isolator disposed between the upstream and downstream lengths of amplifier fiber such that passage of backscattered signal radiation from the latter to the former is substantially blocked. In preferred embodiments counter-propagating pump radiation is coupled into the downstream length of amplifier fiber, and wavelength-selective means are provided for shunting the pump radiation around the optical isolator. The described FRA is advantageously incorporated into optical fiber communication systems. Exemplarily it can serve as power amplifier, as pre-amplifier, or as in-line amplifier. For instance, it can be used to replace conventional opto-electronic repeaters in existing 1.3 μm fiber communication systems, or it can be used as power amplifier in a multi-subscriber optical fiber CATV system. In a still further exemplary embodiment, the FRA is used as a distributed pre-amplifier in a remotely pumped fiber communication system.
TL;DR: In this paper, a band-pass wavelength division multiplexer is used to separate the returned wavelengths from an array of gratings, and interferometric processing is performed to attain high-strain resolution.
Abstract: A multiplexing approach for high-resolution sensing with Bragg gatings is described. The scheme uses a band-pass wavelength division multiplexer to separate the returned wavelengths from an array of gratings, and interferometric processing to attain high-strain resolution. A strain resolution of 1.5 nanostrain//spl radic/Hz is demonstrated, with a sensor bandwidth of 10 Hz-2 kHz for four sensors.
Patent•
21 Mar 1996TL;DR: In this article, an optical wavelength demultiplexer is used to detect the difference between the wavelength of a transmitter and a wavelength minimizing the loss in the optical-wavelength demultiper.
Abstract: A wavelength division multiplexing optical transmission apparatus comprises an optical wavelength demultiplexer which demultiplexes, for each wavelength, the wavelength division multiplex optical signal transmitted via an optical fiber, receivers which receive the output beams from the optical wavelength demultiplexer, a wavelength detector that detects the difference between the wavelength of a transmitter and a wavelength minimizing the loss in the optical wavelength demultiplexer, and an alarm generator that determines an abnormality when the wavelength difference has exceeded an allowable value and raises the alarm.