Showing papers on "Dispersion-shifted fiber published in 1994"
TL;DR: A simple double-pass fiber noise measurement and control system is described, which is demonstrated to provide millihertz accuracy of noise cancellation.
Abstract: Although a single-mode optical fiber is a convenient and efficient interface/connecting medium, it introduces phase-noise modulation, which corrupts high-precision frequency-based applications by broadening the spectrum toward the kilohertz domain. We describe a simple double-pass fiber noise measurement and control system, which is demonstrated to provide millihertz accuracy of noise cancellation.
539 citations
TL;DR: In this article, a technique to design the channel frequency allocation in order to minimize the crosstalk due to FWM is presented, which is obtained at the expense of some expansion of the system bandwidth.
Abstract: Crosstalk due to four-wave mixing (FWM) is the dominant nonlinear effect in long-haul multichannel optical communication systems employing dispersion-shifted fiber. A technique to design the channel frequency allocation in order to minimize the crosstalk due to FWM is presented. It is shown that suitable unequal channel separations can be found for which no four-wave mixing product term is superimposed on any of the transmitted channels. This is obtained at the expense of some expansion of the system bandwidth. Simulations are presented to show the effectiveness of this technique in a 10-channel, 10-Gb/s per channel, system. >
263 citations
TL;DR: A linearly chirped in-fiber Bragg grating is reported that can compensate at 1549 nm for the dispersion of standard telecommunications optical fiber optimized for 1300-nm operation.
Abstract: A linearly chirped in-fiber Bragg grating is reported that can compensate at 1549 nm for the dispersion [ approximately -19 ps/(nmkm)] of standard telecommunications optical fiber optimized for 1300-nm operation.
245 citations
TL;DR: In this paper, a spatial mode-converter is used to selectively excite a higher order mode in specially designed multimode fiber, which can be used to compensate the positive dispersion in conventional single-mode fiber spans.
Abstract: Higher order spatial modes in optical fibers exhibit large, negative chromatic dispersion when operated near their cutoff wavelength. By using a spatial mode-converter to selectively excite a higher order mode in specially designed multimode fiber, this dispersion can be used to compensate the positive dispersion in conventional single-mode fiber spans. In this paper, issues related to compensating fiber and mode-converter design are explored. Experimental measurements in specially designed two-mode fibers operated in LP/sub 11/ mode show negative dispersion as large as -70 ps/nm/spl middot/km at 1555 nm. Pulse propagation and system experiments employing spatial mode-converters to excite LP/sub 11/ mode in a two-mode fiber demonstrate the feasibility of this technique for dispersion compensation in lightwave systems. >
233 citations
TL;DR: In this article, the characteristics of 1.55 /spl mu/m Er-doped superfluorescent fiber sources (SFSs) intended for fiber-optic gyroscope (FOG) applications are explored theoretically and experimentally.
Abstract: The characteristics of 1.55 /spl mu/m Er-doped superfluorescent fiber sources (SFS's), intended for fiber-optic gyroscope (FOG) applications, are explored theoretically and experimentally. With proper selection of the source configuration, fiber length, pump wavelength, pump power, and fiber composition, we show that it is possible to meet the stringent requirements of the FOG, including a high output power, broad emission bandwidth, and excellent spectral thermal stability. Variations of the mean wavelength, spectral width, and output power of the SFS with fiber length, pump power, pump wavelength, and temperature are modeled for representative sources pumped near 980 nm or 1.48 /spl mu/m, and are shown to be in good agreement with experimental results. The effects of a multimoded pump, erbium ion pair, and optical feedback are also assessed. This study indicates that the Er-doped SFS is an excellent candidate for the FOG and for other applications requiring spatial coherence and low temporal coherence. >
226 citations
TL;DR: In this article, an analytical model for two-, three-, and four-level system rare-earth-doped fiber amplifiers and lasers is presented, where fiber-amplifier gain is expressed in terms of attenuation coefficients, intrinsic saturation powers, and cross-saturation powers at the pump and signal wavelengths.
Abstract: An analytical model for two-, three-, and four-level system rare-earth-doped fiber amplifiers and lasers is presented. The theory is applicable to dopants such as erbium, neodymium, thulium; praseodymium, and ytterbium. Fiber-amplifier gain is expressed in terms of attenuation coefficients, intrinsic saturation powers, and cross-saturation powers at the pump and signal wavelengths. These parameters can be directly determined from one- and two-beam fiber-transmission measurements. System-independent formulas are given for the slopes and thresholds of ring and linear fiber lasers. Good agreement between theory and experiment has been shown for erbium-doped fiber amplifiers and lasers and thulium-doped fiber lasers. Because of the finite-pump-level lifetime, three- and four-level models predict a flattening of the fiber laser slope at higher pumping powers when the fiber is shorter than the optimum length. Approximate system-independent solutions are also given for fiber amplifiers with excited-state absorption at either the pump or signal wavelengths. A novel technique, requiring only one tunable light source, is proposed for finding the best pump wavelength when pump ESA is present. The two-level analytical model recently developed for erbium-doped fibers is a special case of this theory. >
206 citations
TL;DR: In this paper, the authors show that by reducing the system nonlinearity via pulse stretching and employing net positive dispersion cavities, pulses of sub-100fs duration and ≳100 pJ energy are readily generated.
Abstract: To date most passively mode‐locked erbium‐doped fiber laser systems have employed solitons for short pulse generation, and ultrashort high energy pulses have been difficult to achieve. We show that by reducing the system nonlinearity via pulse stretching and employing net positive dispersion cavities, pulses of sub‐100‐fs duration and ≳100 pJ energy are readily generated. Data are presented for varying net dispersion in a fiber ring.
184 citations
TL;DR: A high-bandwidth and low-loss graded-index polymer optical fiber is obtained by using the interfacial-gel polymerization technique, in which an unreactive component is used to obtain the quadratic refractive-index distribution.
Abstract: We successfully obtained a high-bandwidth (1 GHz km) and low-loss (90 dB/km at 0.572 μm of wavelength) graded-index polymer optical fiber by using the interfacial-gel polymerization technique, in which we used an unreactive component to obtain the quadratic refractive-index distribution. This high-bandwidth graded-index polymer optical fiber makes it possible to transmit a high-speed optical signal in a short-range network, which is not possible when we use the step-index type of polymer optical fiber commercially available.
139 citations
TL;DR: Using a tapered in width square active waveguide and bulk InGaAsP/InP material, the authors demonstrate a polarisation independent amplifier structure operating at 1550 nm with a reduced far-field divergence.
Abstract: Using a tapered in width square active waveguide and bulk InGaAsP/InP material we demonstrate a polarisation independent amplifier structure operating at 1550 nm with a reduced far-field divergence. Improvement of coupling efficiency enables us to achieve a 25 dB fiber to fiber gain together with 9 dBm fiber saturation output power for 150 mA bias current. A 200 ps gain recovery time allows fast gating or wavelength conversion. >
132 citations
Patent•
26 Jan 1994
TL;DR: In this article, a multiuser remote active multipoint fiber laser sensor includes a plurality of fiber lasers (12, 14, 16), each having a pair of Bragg gratings (18, 20), embedded in a fiber and excited by a common pump light.
Abstract: A remote active multipoint fiber laser sensor includes a plurality of fiber lasers (12, 14, 16), each having a pair of Bragg gratings (18, 20), embedded in a fiber (10) and excited by a common pump light (30). The lasers (12, 14, 16) lase at different longitudinal modes (lasing wavelengths) and emit light (32, 34, 36), at their respective wavelengths (μ1, μ2, μn). The lasing wavelength of each laser shifts due to perturbations, such as strain or temperature, applied thereto. The output light (32, 34, 36) is fed to a spectrum analyzer (50) where the wavelength shift is analyzed. A signal processor (54) reads the wavelength shift and provides a signal on lines (56) indicative of the perturbation at each of the lasers/sensors (12-16). Alternatively, a single laser may be used as a single sensor. Alternatively, birefringent fiber may be used as the fiber cavities (21) and the two polarizations are beat together to form a lower difference or ''beat'' frequency, thereby allowing lower frequency detection devices to be used.
128 citations
TL;DR: In this article, the authors proposed a method of dispersion-supported transmission of 10 Gb/s signals at 1.53 /spl mu/m wavelength on standard single-mode fiber with zero dispersion.
Abstract: Using the new method of dispersion-supported transmission, 10 Gb/s signals at 1.53 /spl mu/m wavelength are transmitted on standard single-mode fiber with zero dispersion at 1.3 /spl mu/m via the record length of 253 km without in-line regeneration. Detailed experiments with a directly modulated laser demonstrate the system performance for different fiber lengths ranging from 0 up to 253 km. >
TL;DR: A multiwavelength comb is obtained from Er(3+) - and Nd(3+)-doped fiber lasers by incorporation of a section of multimode optical fiber into an otherwise single-mode fiber ring cavity.
Abstract: A multiwavelength comb is obtained from Er(3+) - and Nd(3+)-doped fiber lasers by incorporation of a section of multimode optical fiber into an otherwise single-mode fiber ring cavity. This combination of fiber types acts as a wavelength-dependent filter in the laser through spatial mode beating between the LP(01) and LP(11) modes in the multimode fiber.
Patent•
28 Dec 1994
TL;DR: In this paper, a coupling arrangement for non-axial transfer of light power between a multi-mode light source (LS), having a substantially circu lar emission with a divergence angle αs, and a multiamodal optical fiber (FF) with a cross section Ac, through a length of an intermediate feeding multimode optical fiber having an end with cross section area Af coupled with said light source and one portion fused to said optical fiber, is presented.
Abstract: A coupling arrangement for non-axial transfer of light power between a multi-mode light source (LS), having a substantially circu lar emission with a divergence angle αs, and a multi-mode optical fiber (FF) with a cross section Ac, through a length of an intermediate feeding multi-mode optical fiber (IF) having an end with cross section area Af coupled with said light source (LS) and one portion fused to said optical fiber (FF). Said feeding fiber (IF) has a progressively tapered portion and is fused to said multi-mode optical fiber (FF) at a region of the tapered fiber, and in that the relationship between the acceptance angle αf of the feeding fiber (IF) and the emission angle αs of the light source (LS) is expressed by: αf = k . αs where k is a positive constant greater than 1.
TL;DR: The performance of a prototype device - a 1535-nm channel-dropping filter with 0.7-nm bandwidth, 70% peak transmission, and 13-dB isolation- shows great promise for wavelength-division-multiplexing and line-filtering applications.
Abstract: A low-insertion-loss, all-single-mode fiber, wavelength-division-multiplexing filter comprising a four-port polished coupler and a strong fiber grating is demonstrated. The device operated in a novel way by a process we call grating-frustrated directional coupling. A fiber grating, present in only one half of the coupler, frustrates the transference of power to the other half within a narrow wavelength range. The performance of a prototype device - a 1535-nm channel-dropping filter with 0.7-nm bandwidth, 70% peak transmission, and 13-dB isolation-shows great promise for wavelength-division-multiplexing and line-filtering applications.
TL;DR: A novel optical fiber that consists of a chain of alternating segments of standard telecommunication fiber and dispersion-shifted fiber is proposed for the generation of a soliton pulse train based on nonlinear transformation of an optical beat signal.
Abstract: A novel optical fiber [comblike dispersion-profiled fiber (CDPF)] that consists of a chain of alternating segments of standard telecommunication fiber and dispersion-shifted fiber is proposed for the generation of a soliton pulse train based on nonlinear transformation of an optical beat signal. A totally integrated all-optical fiber source of a 59.1-GHz train of 2.2-ps solitons is demonstrated with a CDPF. For a beat signal generator we use a dual-frequency erbium fiber laser incorporating fiber grating reflectors that provides 16-kHz linewidths and a low phase noise of optical beating (<5 × 10−5). Significant suppression of stimulated Brillouin scattering, which is essential for this technique, is achieved in the CDPF.
TL;DR: In this article, a compensation technique based on propagating the signals through a specially designed fiber with large negative dispersion for the LP/sub 01/mode, thereby ending up with zero net pulse spreading is presented.
Abstract: The practical implementation of erbium-doped fiber amplifiers with gain at 1.55 /spl mu/m allows long unrepeatered transmission distances. However, in order to realize high data rates over these distances with already installed standard single mode fiber, techniques must be found to overcome the pulse spreading due to the positive chromatic dispersion of the transmission fiber in this window, we review a compensation technique based on propagating the signals through a specially designed fiber with large negative dispersion for the LP/sub 01/ mode, thereby ending up with zero net pulse spreading. The basis of the concept are discussed and a key figure of merit for dispersion compensating devices is defined. The design and optimization of dispersion compensating (DC) fiber is described with special attention to practical concerns including packaging and manufacturability. We describe experimental fabrication results of DC fiber, results of using the fiber to make compact dispersion compensating modules, and the outcome of recent systems experiments incorporating the fiber. >
Patent•
AT&T1
TL;DR: In this article, a power law core refractive index profile is proposed for the optical fiber that can advantageously be used to compensate chromatic dispersion in an optical fiber communication system, typically a system that is upgraded from 1.3 μm to 1.55 μm operating wavelength.
Abstract: Disclosed is optical fiber that can advantageously be used to compensate chromatic dispersion in an optical fiber communication system, typically a system that is upgraded from 1.3 μm to 1.55 μm operating wavelength (λ op ). The fiber typically has a power law core refractive index profile, a refractive index "trench" surrounding the core, and a refractive index "ridge" surrounding the trench. The refractive index profile of the fiber preferably is designed such that the fiber supports the fundamental mode (LP 01 ), does not support the LP 11 mode but does support the LP 02 mode, all at λ op . At λ op , LP 01 has dispersion more negative than -150 ps/nm·km and, in a preferred embodiment, LP 01 also has negative dispersion slope at λ op . In a further embodiment of the invention the refractive index profile is designed such that the cut-off wavelength of the LP 11 mode is less than that of the higher order mode, typically LP 02 , and less than λ op , such that the fiber does not support propagation of the LP 11 mode. In some preferred embodiments the fiber is designed to have dispersion more negative than about -90 ps/nm·km and loss less than about 0.5 dB/km at λ op ˜1.55 μm.
TL;DR: The field of fiber optics still reserves some surprises as mentioned in this paper and the past few years have seen stunning developments in reaction to advances in rare earth-doped fiber amplifiers and nonlinear (or soliton) pulse propagation in fibers.
Abstract: After nearly two decades of research in fiber‐optics technology, what could possibly remain to be discovered? Clearly, the design of optical fibers cannot be improved forever. With current technology, fibers can transmit infrared (1.5‐micron wavelength) light pulses in a single electromagnetic mode with a minimal power loss of 5% per kilometer and without dispersion; such performance is forever fixed by Maxwell's equations and the physics of silica glass waveguides. Yet the field of fiber optics still reserves some surprises. Indeed, the past few years have seen stunning developments in reaction to advances in rare‐earth‐doped fiber amplifiers and nonlinear (or soliton) pulse propagation in fibers.
TL;DR: In this paper, the authors describe tunable wavelength conversion using fiber four-wave mixing using two pump lights, where a signal light is converted from an arbitrary frequency to another one regardless of the zero-dispersion wavelength of the fiber.
Abstract: Tunable wavelength conversion is described using fiber four-wave mixing. Utilizing two pump lights, a signal light is converted from an arbitrary frequency to another one regardless of the zero-dispersion wavelength of the fiber. Selective conversion is also possible by adjusting one of the pump light frequencies, where one of the multiplexed signals is selectively converted. >
TL;DR: Dispersion compensation is demonstrated experimentally by pulse compression with the use of chirped optical fiber Bragg gratings by the Gaussian intensity profile of the 240-nm wavelength beam used for holographic sidewriting of the grating.
Abstract: Dispersion compensation is demonstrated experimentally by pulse compression with the use of chirped optical fiber Bragg gratings. The gratings chirp is self-induced by the Gaussian intensity profile of the 240-nm wavelength beam used for holographic sidewriting of the grating. Chirped pulses generated by a 1.55-microm gain-switched distributed-feedback laser with an initial pulse duration of 21 ps and a spectral width of 0.7 nm are compressed to 13 ps, in good agreement with theory.
TL;DR: In this paper, the laser performance at 491 and 635nm of praseodymium-doped fluorozirconate fiber pumped at 1.01µm and 835nm is described and is interpreted with analytical solutions to the rate equations.
Abstract: The laser performance at 491 and 635nm of praseodymium-doped fluorozirconate fiber pumped at 1.01µm and 835nm is described and is interpreted with analytical solutions to the rate equations. Spectroscopic measurements of the absorption and the emission cross sections are presented, and the values are shown to be consistent with the observed lasing performance. The analytical model is shown to be a reliable indication of the optimum length of fiber for operation on the three-level 491nm transition.
TL;DR: The role of third-order dispersion on the propagation, stability, and interactions of solitons in optical fiber transmission links and fiber lasers is analyzed.
Abstract: We analyze the role of third-order dispersion on the propagation, stability, and interactions of solitons in optical fiber transmission links and fiber lasers.
TL;DR: In this article, the analysis of parametric and Raman effects in the framework of a single approach is presented, where the transformation of gain spectra for Stokes and anti-Stokes waves under pump wavelength tuning is discussed.
Abstract: We present the analysis of parametric and Raman effects in the framework of a single approach. We discuss the transformation of gain spectra for Stokes and anti-Stokes waves under pump wavelength tuning from the region of positive group-velocity dispersion to the region of negative group-velocity dispersion for different types of phase-matching mechanism in a birefringent fiber.
TL;DR: Oscillation in a Tm(3+) and Ho( 3+) codoped silica fiber from the (5)I(7) ?
Abstract: We have observed oscillation in a Tm3+ and Ho3+ codoped silica fiber from the 5I7 → 5I8 transition of Ho3+ in the 2-μm region, by pumping the fiber laser into a Tm3+ absorption between 800 and 830 nm. By a change in the cavity length, the laser was tunable between 2.037 and 2.096 μm. When the laser was pumped with a Ti:sapphire laser at 820 nm, an absorbed threshold power of 214 mW, a slope efficiency of 4.2%, and maximum extracted power of 12.5 mW were measured.
TL;DR: In this paper, the authors proposed a novel approach to combating the pulse-broadening effect of group-velocity dispersion (GVD) in a fiber-optic communication link, where linear loss in the fiber is balanced by a chain of periodically spaced, phase sensitive optical amplifiers.
Abstract: Recently, we proposed a novel approach to combating the pulse-broadening effect of group-velocity dispersion (GVD) in a fiber-optic communication link (IEEE Photon. Technol. Lett., vol. 5, pp. 669-672, 1993). In our scheme, linear loss in the fiber is balanced by a chain of periodically spaced, phase-sensitive optical amplifiers. In this paper, we present a detailed analysis of pulse propagation in such a fiber line showing that, due to attenuation in the quadrature orthogonal to the amplified quadrature, it is possible for a pulse to propagate without significant broadening over lengths many times longer than the usual dispersion length of the fiber. An averaged equation for pulse evolution over distances longer than the amplifier spacing is derived. The effect of optical-phase fluctuations between the propagating pulse and the amplifiers is also considered. Since our proposed scheme does not rely on the formation of solitons in the fiber, it can be implemented in both the positive and negative GVD regions, and it does not require a minimum peak power for the pulses. >
TL;DR: In this paper, a new type of fiber acousto-optic device based on tapered single-mode fiber was described, where the overlap between the acoustic and optical waves is complete, so very little acoustic power is required.
Abstract: A new type of fiber acousto-optic device, based on tapered single-mode fiber, is described. Unlike earlier designs, the overlap between the acoustic and optical waves is complete, so very little acoustic power is required. Maximum coupling in an experimental device was attained for an electrical drive power of just 0.5 mW. >
TL;DR: A simple, effective technique for launching higher-order modes into a double-mode optical fiber by using an optical phase shifter at the input end is demonstrated.
Abstract: We demonstrate a simple, effective technique for launching higher-order modes into a double-mode optical fiber by using an optical phase shifter at the input end. The suppression of the lowest-order mode was measured (but not limited) to be 27 dB.
Patent•
06 Sep 1994
TL;DR: In this article, an upconversion fiber laser with a double-clad fiber is pumped with a laser-diode-based laser pump source, the inner cladding of the fiber forming a low transmission loss waveguide for the pump light.
Abstract: An upconversion fiber laser with a double-clad fiber is pumped with a laser-diode-based laser pump source, the inner cladding of the fiber forming a low transmission loss waveguide for the pump light. The central core of the fiber is doped with an active lasing ionic species capable of undergoing upconversion excitation, such as certain rare earth ionic species. The use of a double-clad fiber permits the use of high power, high brightness laser diodes, including those with broad emitting apertures, as well as high power diode laser pumped fiber lasers, as the pump source, thereby achieving higher pump intensities within the upconversion laser fiber and improved upconversion efficiency. Pump brightness can be further increased with multiple pump schemes which use multiple pump wavelengths in different absorption bands, multiple pump wavelengths within the same absorption band, pump light from pairs of cross-polarized sources, and pumping from both ends of the fiber.
TL;DR: A new technique is reported for obtaining a wide wavelength conversion range in fiber four-wave mixing by cut into short fiber pieces and rearranged, considering the zero-dispersion wavelength of each fiber piece.
Abstract: A new technique is reported for obtaining a wide wavelength conversion range in fiber four-wave mixing. One fiber is cut into short fiber pieces and rearranged, considering the zero-dispersion wavelength of each fiber piece. With this rearrangement, the wavelength conversion range is expanded, compared with that in the original fiber. An experiment using a 6-km fiber confirms the technique.
TL;DR: In this paper, a tapered fiber optical probe with an aperture of around 100 nm, served as the means for delivering pump radiation while simultaneously collecting the Stokes radiation from the diamond specimen.
Abstract: Raman spectroscopy with subwavelength spatial resolution of a diamond sample was recorded using a tapered fiber optical probe in conjunction with a conventional Raman spectrometer. The experiment demonstrates the potential of suboptical wavelength resolution analytical spectroscopy. The tapered fiber optical probe with an aperture of around 100 nm, served as the means for delivering pump radiation while simultaneously collecting the Stokes radiation from the diamond specimen. Comparing the magnitude of the Raman scattering measured with the submicron single mode fiber probe to similar signals obtained with a nontapered probe made of the same type of fiber, illustrates the potential increase in effective optical aperture resulting from the close approach of the fiber to the surface.