Optical amplifiers are used to create laser guide stars which provide feedback to the adaptive optics control systems which dynamically adjust the shape of the mirrors in the largest astronomical telescopes. In the systems discussed earlier, optical noise is not accompanied with the optical signal that reaches the optical receiver, and therefore, ber can be reduced by increasing the level of signal optical power. It may be a preamplifier, mixer, or a complete receiver. Noise figure nf measures of degradation of the signalto noise ratio snr, caused by components, such as amplifiers, in an rf signal chain. Pdf noise figure improvement in semiconductor optical. Theory and measurement techniques for the noise figure of optical. Noise figure improvement in semiconductor optical amplifiers. Analysis techniques for soa characteristics analysis techniques for the nf and output power characteristics of an soa will be described in this section. Consider a system with cascade of two gain stages having gains of, and with noise figure of and respectively. Invited paper theory and measurement techniques for the.
Noise figure of verticalcavity semiconductor optical amplifiers. Boosting of an optical signal without any conversion of. Apr 21, 2012 noise figure of cascade of two stages. Noise figure improvement in semiconductor optical amplifiers by holding beam at transparency scheme. The noise power from a simple load is equal to ktb, where k is boltzmanns constant, t is. Noise figure of optical amplifiers request pdf researchgate. Alan kost is an associate research professor of optical sciences in the university of arizona. Figure 1 shows three ways in which optical amplifiers can be used to enhance the performance of optical data links. The analysis technique for the nf characteristics of an soa is introduced in the literature 4. Definitions of noise figure are discussed along with applications of noise figure to circuits incorporating cascades of amplifiers and other optical and optoelectronic devices.
Calculating noise figure in op amps introduction noise figure is commonly used in communications systems because it provides a simple method to determine the impact of system noise on sensitivity. The gain for an optical amplifier is defined by the equation. Soas include highcoupling loss, polarization dependence, and a higher noise figure. This makes the noise figure one of the most important properties of optical amplifiers for their applications in optical communication systems. Noise analysis in operational amplifier circuits rev. Yuksek, qi song and ozdal boyraz eecs department, university of california, irvine, 92697, email. S represents the linear optical signal power and n is the linear optical noise power optical signal to noise ratio osnr db is the measure of the ratio of signal power to noise power in an optical channel.
Two noise figure definitions for optical amplifiers are described that mesh with the ieee definition in the classical non optical regime. An important result of quantum optics 1 is that a phaseinsensitive highgain optical amplifier has a noise figure of at least 3 db. Noise figure of verticalcavity semiconductor optical. Boosting of an optical signal without any conversion of the. Optical amplifiers are used extensively in fiber optic data links. The proper definition of noise figure of optical amplifiers. Osa the proper definition of noise figure of optical amplifiers. Photonics and optical communication, spring 2005 dr. The currently used noise figure definition for optical amplifiers is critiqued. Raman amplifiers optimizing the noise figure becomes a challenge specially when change of the fiber length, attenuation, cladding and core index values are changed.
Flicker noise flicker noise is also called 1f noise. It is a number by which the performance of an amplifier or a radio receiver can be specified, with lower values indicating better performance. Mean value gaussian probability density function rms value noise signal 99. Invited paper theory and measurement techniques for the noise. The purpose of the present paper is to present a consistent approach to modeling the noise figure of optical amplifiers and other optical components and to. New pumping methods and materials are also improving the performance of raman amplifiers. This concept of a noise figure can also be applied to optical amplifiers 1 5, but it should be noted that not all definitions in the literature are the same. His areas of research include optical data storage, optical communications, integrated optics, nanooptics. Semiconductor optical amplifiers soas fiber raman and brillouin amplifiers rare earth doped fiber amplifiers erbium edfa 1500 nm, praseodymium pdfa 0 nm the most practical optical amplifiers to date include the soa and edfa types. Erbiumdoped fiber amplifiers is exarnined, and furthermore an account of the measurements of absorption and fluorescence spectra, amplification and noise figures is given. Hausthe proper definition of noise figure of optical amplifiers conference on optical fiber communicationofc99, optical society of america, washington feb. The noise performance of an optical amplifier is characterized by its noise figure nf, which is defined as the ratio of the signaltonoise ratio snr at the amplifier output. He came with ample prior experienceboth for this work and for his age.
Noise figure nf measures of degradation of the signaltonoise ratio snr, caused by components, such as amplifiers, in an rf signal chain. We also measure the variation in noise figure due to the degradation in pump optical signal to noise ratio and also as a function of the input signal powers. Frequencyresolved noise figure measurements of phase in. As an example, we consider an erbiumdoped fiber amplifier, as it could be used in optical fiber communications, e. Theory and measurement techniques for the noise figure of.
Optical fiber transmission has revolutionized networking and communication systems. Noise figure nf and noise factor f are measures of degradation of the signalto noise ratio snr, caused by components in a signal chain. Method to improve the noise figure and saturation power in. From the last lecture, remember the general expression for the optical amplifier noise figure, fn. Multiple communication devices, like optical transmitters and receivers, are used in optical fiber. This limit can be reached for a fourlevel laser amplifier, a nondegenerate optical parametric amplifier, or a raman amplifier, whereas quasithreelevel amplifiers have higher noise figures. Request pdf noise figure of optical amplifiers the implications of the heisenberg uncertainty principle for the optical amplifier noise figure are reexamined. Types of noise noise analysis in operational amplifier circuits 3 the terms 4ktr and 4ktr are voltage and current power densities having units of v2hz and a2hz.
In steady state, dn2 dt 0, the ratio of level 1 and level 2 population to the total population can be written as. Leif was about thirty, well before the turn of the century, he joined analog devices as an ic designer. It can be shown, that the noise factor f remains unchanged, if the signaltonoise ratio are related to the electric power after the optoelectric conversion. Gain, noise figure and forward ase spectrum of a forwardpumped erbiumdoped fiber amplifier. Optical amplifiers, edfa, erbium doped fiber, gain, noise figure 1. The impacts of the signal power and the signal to noise ratio on the noise figure are systematically measured. It can be shown, that the noise factor f remains unchanged, if the signaltonoise ratio are related to. N0 looking at this equation, we need to minimize n0, which takes into account the. Friis introduced in 1944 the noise figure nf concept which characterized the degradation in signal to noise ratio snr by the receiver. Electrical noise figure measurements are often thought of as. It is the ratio of the signaltonoise ratio at the input of the amplifier to the signaltonoise ratio at the output of the amplifier. Rp photonics encyclopedia tutorial fiber amplifiers.
The noise behavior of semiconductor laser or fiber amplifiers results from fig. Rp photonics encyclopedia tutorial fiber amplifiers, part. Thus, gain and noise figure performance of an edfa given with its physical parameters can be graphically obtained or the required physical parameters of an edfa with desired operating performance can easily be optimised. In principle, the noise figure of an optical amplifier can be measured electrically or optically. By introducing an amplified spontaneous emission source as additional noise, two sets of experimental schemes are designed to measure noise figure characteristics of erbiumdoped fiber amplifier employed in an analog optical system. Figure 1 illustrates the basics of a semiconductor optical amplifier. Another important purpose of the noise figure is to characterize the amount of ase produced by the amplifier, because the ase tends to accumulate in the communcation system. Noise figure is a number by which the noise performance of an amplifier or a radio receiver can be specified. Noise figure and logarithmic amplifiers the wit and wisdom of dr.
Friis introduced in 1944 the noise figure nf concept which characterized the degradation in signal. The noise figure is the difference in decibels db between the noise output of the actual receiver to the noise output of an ideal receiver with the same overall gain and bandwidth when the receivers are connected to matched sources at the standard noise temperature t 0 usually 290 k. An optical fiber amplifier is a fiber optic device used to amplify optical signals directly without conversion into electrical signals. In addition to thermal noise, amplifiers or other devices with semiconductors also contribute to the total system noise. Optical amplifiers in order to transmit signals over long distances 100 km it is necessary to compensate for attenuation losses within the fiber. The noise figure number, displayed in decibels db, represents the performance by which an amplifier or rf receiver can be measured. Following the discussion on thermal noise and its modeling and noise figure computation for a simple resistor network, in this article let us discuss the noise figure of cascaded stages definition of noise figure. In part 2, it was mentioned already that most fiber amplifiers, e. Optical receiver tias must achieve a wide bandwidth, a low inputreferred noise current, and a reasonable gain to minimize the noise contribution of the subsequent stages. Request pdf theory and measurement techniques for the noise figure of optical amplifiers the theoretical basis for the noise figure of. Eisenstein, noise sp ectra of semiconductor optical amplifiers. Figure 1 shows graphically how the probability of the amplitude relates to the rms value. The amplified spontaneous emission ase, is regarded as noise in the optical amplifiers and considered as an average in both polarizations.
Alan kost associate research professor of optical sciences, university of arizona. Rongqing hui, in introduction to fiberoptic communications, 2020. The noise figure of optical amplifiers has been extensively studied 815. Noise figure to characterize the receiver alone, harald t.
Noise figure of highrepetitionrate optical parametric amplifiers in silicon xinzhu sang, enkuang tien, feng qian, nuh s. Semiconductor optical amplifiers with low noise figure. Desurvire, on the physical origin of the 3db noise figure limit in laser and parametric optical amplifiers, opt. Eindhoven university of technology master an optical amplifier. High noise figure and crosstalk levels due to nonlinear phenomenon such as 4 wave mixing. On the other hand, in a longdistance optical transmission system employing multiple inline optical. The noise performance of an optical amplifier is characterized by its noise figure nf, which is defined as the ratio of the signaltonoise ratio snr at the amplifier. The noise figure can be increased by excess losses at the amplifier. Low price with high volume production disadvantages 1. Two noise figure definitions for optical amplifiers are described that mesh with the ieee definition in the classical nonoptical regime. There, we have some signal reabsorption, which clearly increases the excess noise. We examine the concept of optical noise figure in to twoport devices. High noise figure and crosstalk levels due to nonlinear phenomenon such as 4wave mixing.
Evaluation of edfa characteristics as key devices in longdistance, largecapacity transfers described in iec61290 and jisc6122 specifies the importance of gain and noise figure nf measurement items. The noise figure number, displayed in decibels db, represents the performance by which an amplifier or rf receiver can. The noise power at the output of the first stage is the sum of. A booster amplifier is used to increase the optical output of an optical transmitter just before the. Noise figure and logarithmic amplifiers analog devices. On the other hand, in a longdistance optical transmission system employing multiple inline optical amplifiers, the level of optical. Method to improve the noise figure and saturation power in multicontact semiconductor optical amplifiers. Essentially the noise figure defines the amount of noise an element adds to the overall system. Rp photonics encyclopedia noise figure, quantum noise. Request pdf noise figure of optical amplifiers the implications of the heisenberg uncertainty principle for the optical amplifier noise figure are re examined.
Haus, the noise figure of optical amplifiers, ieee photonics technology letters, vol. Analysis and characterization of semiconductor optical amplifiers. Fiber amplifiers as well as both traveling wave tw and fabryperot. The lower the value of the noise figure, the better the performance.1089 380 528 1122 429 1450 1511 1033 1503 965 769 569 1476 1456 560 993 197 602 1573 1087 174 87 130 814 451 910 805 1065 661 487 559 884 986 294 1327 757 1095 642