Optical power handling capacity of low loss optical fibers as determined by stimulated Raman and brillouin scattering.
TL;DR: These effects of stimulated Raman and Brillouin scattering must be considered in the design of optical communication systems using low loss fibers especially when low loss optical fibers are used.
Abstract: The effect of stimulated Raman and Brillouin scattering on the power handling capacity of optical fibers is considered and found to be important especially when low loss optical fibers are used. A critical power below which stimulated effects may be neglected is defined for forward and backward Raman scattering and for backward Brillouin scattering. This critical power is determined by the effective core area A, the small signal attenuation constant of the fiber alpha, and the gain coefficient for the stimulated scattering process (gamma0), by the approximate relation P(crit) approximately 20Aalpha/(gamma0). For a fiber with 20-dB/km attenuation and an area of 10(-7) cm(2)P(crit) approximately 35 mW for stimulated Brillouin scattering. For stimulated Raman scattering P(crit) is approximately two orders of magnitude higher. It is concluded that these effects must be considered in the design of optical communication systems using low loss fibers.
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04 Oct 2006
TL;DR: In this paper, a review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime.
Abstract: A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.
3,361 citations
TL;DR: Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion.
Abstract: Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion. In the case of anomalous dispersion (∂2ω/∂k2>0) discussed here [the case of normal dispersion (∂2ω/∂k2<0) will be discussed in a succeeding letter], the stationary pulse is a ``bright'' pulse, or envelope soliton. For a typical glass fiber guide, the balancing power required to produce a stationary 1‐ps pulse is approximately 1 W. Numerical simulations show that above a certain threshold power level such pulses are stable under the influence of small perturbations, large perturbations, white noise, or absorption.
2,509 citations
TL;DR: In this article, the capacity limit of fiber-optic communication systems (or fiber channels?) is estimated based on information theory and the relationship between the commonly used signal to noise ratio and the optical signal-to-noise ratio is discussed.
Abstract: We describe a method to estimate the capacity limit of fiber-optic communication systems (or ?fiber channels?) based on information theory. This paper is divided into two parts. Part 1 reviews fundamental concepts of digital communications and information theory. We treat digitization and modulation followed by information theory for channels both without and with memory. We provide explicit relationships between the commonly used signal-to-noise ratio and the optical signal-to-noise ratio. We further evaluate the performance of modulation constellations such as quadrature-amplitude modulation, combinations of amplitude-shift keying and phase-shift keying, exotic constellations, and concentric rings for an additive white Gaussian noise channel using coherent detection. Part 2 is devoted specifically to the "fiber channel.'' We review the physical phenomena present in transmission over optical fiber networks, including sources of noise, the need for optical filtering in optically-routed networks, and, most critically, the presence of fiber Kerr nonlinearity. We describe various transmission scenarios and impairment mitigation techniques, and define a fiber channel deemed to be the most relevant for communication over optically-routed networks. We proceed to evaluate a capacity limit estimate for this fiber channel using ring constellations. Several scenarios are considered, including uniform and optimized ring constellations, different fiber dispersion maps, and varying transmission distances. We further present evidences that point to the physical origin of the fiber capacity limitations and provide a comparison of recent record experiments with our capacity limit estimation.
2,135 citations
TL;DR: This paper reviews the current state of the art in terms of continuous-wave and pulsed performance of ytterbium-doped fiber lasers, the current fiber gain medium of choice, and by far the most developed in Terms of high-power performance.
Abstract: The rise in output power from rare-earth-doped fiber sources over the past decade, via the use of cladding-pumped fiber architectures, has been dramatic, leading to a range of fiber-based devices with outstanding performance in terms of output power, beam quality, overall efficiency, and flexibility with regard to operating wavelength and radiation format. This success in the high-power arena is largely due to the fiber’s geometry, which provides considerable resilience to the effects of heat generation in the core, and facilitates efficient conversion from relatively low-brightness diode pump radiation to high-brightness laser output. In this paper we review the current state of the art in terms of continuous-wave and pulsed performance of ytterbium-doped fiber lasers, the current fiber gain medium of choice, and by far the most developed in terms of high-power performance. We then review the current status and challenges of extending the technology to other rare-earth dopants and associated wavelengths of operation. Throughout we identify the key factors currently limiting fiber laser performance in different operating regimes—in particular thermal management, optical nonlinearity, and damage. Finally, we speculate as to the likely developments in pump laser technology, fiber design and fabrication, architectural approaches, and functionality that lie ahead in the coming decade and the implications they have on fiber laser performance and industrial/scientific adoption.
1,689 citations
TL;DR: An applications-oriented review of optical parametric amplifiers in fiber communications is presented, focusing on the intriguing applications enabled by the parametric gain, such as all-optical signal sampling, time-demultiplexing, pulse generation, and wavelength conversion.
Abstract: An applications-oriented review of optical parametric amplifiers in fiber communications is presented. The emphasis is on parametric amplifiers in general and single pumped parametric amplifiers in particular. While a theoretical framework based on highly efficient four-photon mixing is provided, the focus is on the intriguing applications enabled by the parametric gain, such as all-optical signal sampling, time-demultiplexing, pulse generation, and wavelength conversion. As these amplifiers offer high gain and low noise at arbitrary wavelengths with proper fiber design and pump wavelength allocation, they are also candidate enablers to increase overall wavelength-division-multiplexing system capacities similar to the more well-known Raman amplifiers. Similarities and distinctions between Raman and parametric amplifiers are also addressed. Since the first fiber-based parametric amplifier experiments providing net continuous-wave gain in the for the optical fiber communication applications interesting 1.5-/spl mu/m region were only conducted about two years ago, there is reason to believe that substantial progress may be made in the future, perhaps involving "holey fibers" to further enhance the nonlinearity and thus the gain. This together with the emergence of practical and inexpensive high-power pump lasers may in many cases prove fiber-based parametric amplifiers to be a desired implementation in optical communication systems.
857 citations
Cites background from "Optical power handling capacity of ..."
...The gain of the Raman amplifier may be written in decibel units as [56], [57] (24) Here, the Raman gain slope where is the peak Raman gain coefficient and is the effective mode area of the fiber....
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References
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TL;DR: In this article, a glass fiber optical waveguide was used for the construction of wide-band fiber amplifiers and Raman oscillators tunable over a range of 100 A. Even though the Raman cross section is quite small, relatively low threshold for Raman emission can be achieved because high optical power densities are maintained over long lengths of waveguide.
Abstract: Stimulated Raman emission in the visible has been observed in glass‐fiber optical waveguides. Even though the Raman cross section is quite small, relatively low threshold for Raman emission can be achieved because high optical power densities are maintained over long lengths of waveguide. The broad stimulated gain bandwidths available in glass should permit the construction of wide‐band fiber amplifiers and Raman oscillators tunable over a range of 100 A.
412 citations
TL;DR: In this paper, the saturation effect in the stimulated Brillouin scattering of coherent light waves was analyzed and two coupled first-order nonlinear equations for the intensities of the primary and Stokes waves were proposed.
Abstract: An analysis is given of the saturation effect in the stimulated Brillouin scattering of coherent light waves. It is shown that the three coupled nonlinear wave equations describing the complex amplitudes of the forward‐traveling primary and acoustic waves and the backward‐traveling Stokes wave can be replaced for room‐temperature situations by two coupled first‐order nonlinear equations for the intensities of the primary and Stokes waves. These resulting equations are solved exactly and the solutions describe completely the process of photoelastic amplification of the coherent Stokes wave via stimulated Brillouin scattering in both the linear and the nonlinear saturated regimes. The results also give a more realistic estimate of the intensity of the hypersonic wave generated in the process than that made on the basis of either the Manley‐Rowe relationship, which does not take into account the losses, or the usual linear theories, which do not take into account the saturation effect. It is believed that th...
294 citations
TL;DR: In this article, a liquid-core optical waveguide structure was used to reduce the oscillator threshold to less than 5W and significant conversion of pump to Stokes light has been observed.
Abstract: Quasi‐cw stimulated Raman emission in the visible has been obtained from an oscillator cavity with a pump‐power input of less than 5W. This large reduction of oscillator threshold is achieved with the use of a liquid‐core optical waveguide structure. Significant conversion of pump to Stokes light has been observed. Extension of the system to continuous operation and to the study of other nonlinear effects is suggested.
129 citations
103 citations
TL;DR: In this article, a survey of optical attenuation in a series of commercially available silica, SiO2, samples to determine the suitability of this material for fiber optical communications is made.
Abstract: A survey has been made of optical attenuation in a series of commercially available silica, SiO2, samples to determine the suitability of this material for fiber optical communications. The absorptive component of the attenuation was measured by a precision calorimetric technique, while the scattering component was determined by a new method based on spontaneous Brillouin spectroscopy. Both techniques set an upper limit on the loss and are precise to within a fraction of 1 dB/km. Of the samples tested, the best has a total attenuation of less than 3 dB/km at the 1.06‐μ wavelength of the YAlG : Nd laser.
80 citations