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Optical communication essentials gerd keiser pdf books free13.5).49 13.5 Optical Add/Drop Multiplexing An optical add/drop multiplexer (OADM) is a device that allows the insertion or extraction of one or more wavelengths from a fiber at a network node. Cheng, “A new scheme of conical-wedge-shaped fiber endface for coupling between high-power laser diodes and single-mode fibers,” J. LT-2, pp. 4.3.10Temperature Effects An important factor to consider in the application of laser diodes is the temperature dependence of the threshold current Ith(T ). 13.21 Simple passive optical add/drop multiplexer Optical Networks Fig. The gain was similar for both pump directions. In actual systems, both experiments and simulations have shown that acombination of postcompensation and precompensation provides the best solution for dispersion compensation. The particle nature arises from the observation that light energy is always emitted or absorbed in discrete units called quanta or photons. To achieve protection, the signal 5p 8p 4s 1 from a transmitting node is dual-fed into both the 8s 1s5s primary and protection fibers. Thin-film filters are available in a wide range of passbands varying from 50 GHz to 800 GHz and higher for widely spaced channels. Distribution cables are designed for use in intrabuilding cable trays, conduits, and loose placement in dropped-ceiling structures. In this case, SPM causes the pulse to narrow, therebypartly compensating for chromatic dispersion. Devices with very thin depletion regions thus tend to show distinct slow- and fast-response components, as shown in Fig. 5.4 An LED with a circular emitting area of radius 20 mm has a lambertian emission pattern with a 100-W/(cm2 sr) axial radiance at a 100-mA drive current. The effects of modaldistributions in the multimode fiber that result from different numerical apertures and spot sizes on the launch end of the fiber are shown in Fig. For slight bends the excess loss is extremely small and is essentially unobservable. The active node forwards those messages that do not contain its own address on to its next neighbor. 2003 Deals withgeneral requirements, performance evaluation, and mechanical and optical evaluation testing for optical distribution frames (ODF) in a central office environment. Feng, A. Example 7.10 Consider an analog optical fiber system operating at 1550 nm, which has an effective receiver noise bandwidth of 5 MHz. Assuming that the received signal isquantum noise limited, what is the incident optical power necessary to have a signalto-noise ratio of 50 dB at the receiver? (Adapted with permission from Mao, Bodeep, Tkach, Chraplyvy, Darcie, and Dorosier,11 IEEE, 1992.) 475 Nonlinear Effects Increasing the linewidth of the source as the gain bandwidth of SBS is very small. Liu, “Broadbandemission in Er3 -Tm3 codoped tellurite fibre,” Optics Express, vol. 12.8 as it propagates in a fiber. This is the optical power necessary to produce a photocurrent of the same magnitude as the root mean square (rms) of the total noise current, or equivalently, a signalto-noise ratio of 1. Solution: (a) From Eq. (4.5), we have Eg 1.35 0.72(0.57) 0.12(0.57)2 0.97 eV (b) Using this value of the bandgap energy in Eq. (4.3) yields (in micrometers) l(mm) 1.240/0.97 1.27 mm 1270 nm Relative output power Whereas the FWHM power spectral widths of LEDs in the 800-nm region are around 35 nm, this increases in longer-wavelength materials. Anand, Y. However, if the emitting area ofthe source is smaller than the core area, a miniature lens may be placed between the source and the fiber to improve the power-coupling efficiency. 559 Optical Networks (c) MN (M N – 2) d/2 for a star topology where each subscriber is connected individually to the network hub located in one corner of the grid. 601 Optical Fiber CommunicationsAll these factors taken together present a big challenge to devising a comprehensive OPM system. General reviews and detailed concepts of optical receiver designs are given in the literature.1–17 In Sec. This current flow is known as the photocurrent. 4.3.6. In general, the full optical output is needed only from the front facet of the laser—that is, theone to be aligned with an optical fiber. Third-order intermodulaton (IM) distortion products at frequencies fi fj - fk (which are known as triple-beat IM products) and 2fi - fj (which are known as two-tone third-order IM products) are the most dominant, since many of these fall within the bandwidth of a multichannel system. The most commonly usedconstruction for the refractive-index variation in the core is the power law relationship 12 α r n1 1 2 Δ n( r ) a n1 (1 2 Δ )1 2 n1 (1 Δ ) n2 for for 0 r a (2.78) r a Here, r is the radial distance from the fiber axis, a is the core radius, n1 is the refractive index at the core axis, n2 is the refractive index ofthe cladding, and the dimensionless parameter a defines the shape of the index profile. 11. In practice, various phenomena lead to the excitation of more than one mode.1 Studies on the conditions Example 4.11 Assume for GaAs that R1 R2 R 0.32 for uncoated facets (i.e., 32 percent of the radiation is reflected at a facet) and α ª 10 cm–1.However, although the SNR decreases quickly in the first few amplifications, the incremental effect of adding another EDFA diminishes rapidly with an increasing number of amplifiers. Agrawal, Nonlinear Fiber Optics, Academic, San Diego, CA, 4th ed., 2006. The reader can find additional information on the theory of light propagation in fibers, thedesign of links and networks, and the evolution of optical fibers, photonic devices, and optical fiber communication systems in a variety of books and conference proceedings.4–23 This chapter gives an overview of fundamental communications concepts and illustrates how optical fiber transmission systems operate. CHAPTER 5 Power Launching andCoupling In implementing an optical fiber link, two of the major system questions are how to launch optical power into a particular fiber from some type of luminescent source and how to couple optical power from one fiber into another. Veng, D. The high levels of OH ions in early fibers resulted in large absorption peaks at 725, 950, 1240, and 1380nm. The total coupled power is then determined by summing up the contributions from each individual emitting-point source of incremental area dqs r dr, that is, integrating over the emitting area. A typical OTDR consists of a light source and receiver, data-acquisition and processing modules, an information-storage unit for retaining data either inthe internal memory or on an external disk, and a display. 2.25 The four possible transverse electric field and magnetic field directions and the corresponding intensity distributions for the LP11 mode electric and magnetic field directions and the corresponding intensity distributions for the LP11 mode are shown in Fig. 2.3. Conversely, just as any twoorthogonal plane waves can be combined into a linearly polarized wave, an arbitrary linearly polarized wave can be resolved into two independent orthogonal plane waves that are in phase. Jacobs, “A new compound modulation technique for multichannel analog video transmission on fiber,” J. Furthermore, if DI is greater than I B (i.e., m is greaterthan 100 percent), the lower portion of the signal gets cut off and severe distortion will result. Video services are sent downstream with a 1550-nm wavelength. Abe, and T. 84. In addition, fiber optic sensors or variable power Fig. These are plotted in Fig. Birefringent or double-refractive crystals have a property called double refraction. 25. (c)Graded-index fiber: 1.5-dB/km attenuation at 1300 nm. At an operating wavelength of 0.84 mm the value of V is 39 and there are 760 modes in the fiber. For glass fibers, elongations of only about 1 percent are possible before fracture occurs. This optical signal power is referred to as the noise equivalent power or NEP, which is designated in units ofW Hz . Although an OTDR can give precise reflectance values at individual events along a fiber transmission path, it has a limitation in measuring the back reflections near and within the OTDR dead zone. Baseband refers to the technology in which a signal is transmitted directly over a channel. The letters SC were coined by NTT to meansubscriber connector or square connector. 1 and taking FEDFA(dB) 10 log 2nsp from Eq. (11.35) as the amplifier noise figure, then in decibels PASE (dBm) -58 dBm FEDFA(dB) G(dB) (11.40) Using Eq. (11.36) and taking the EDFA output power to be G times the optical input power, Pout GPin, we then have the requirement that in order tohave an acceptable BER, the OSNR must be at least OSNR(dB) Pin(dBm) 58 dBm - FEDFA(dB) 11.6 (11.41) System Applications In designing an optical fiber link that requires optical amplifiers, there are three possible locations where the amplifiers can be placed, as shown in Fig. Since amplifiers and repeaters are expensive to fabricate, install,and maintain, the degree of attenuation in a fiber has a large influence on system cost. The frequency w IF is normally in the radio-frequency range of a few tens or hundreds of megahertz. ed., 2003. 2.4.) As an example, consider the glass–air interface shown in Fig. Kanada, “Evaluation of modal noise in multimode fiber-optic systems,” J. Uekawa, H.For single-component glass the scattering loss at a wavelength l (given in mm) resulting from density fluctuations can be approximated by3,14 (in base e units) αscat 8π 3 3λ 4 (3.4a) ( n2 1)2 k BT f βT Here, n is the refractive index, kB is Boltzmann’s constant, b T is the isothermal compressibility of the material, and the fictive temperature Tf isthe temperature at which the density fluctuations are frozen into the glass as it solidifies (after having been drawn into a fiber). Use connectors in which the end faces make physical contact (the so-called PC connectors). In that case, we can simplify Eq. (11.30) by examining the magnitudes of the various noise components. 2.3.3 Step-Index FiberStructure We begin our discussion of light propagation in an optical waveguide by considering the step-index fiber. Typical attenuation dead zones range from 10 to 25 m. This network category encompasses connections that extend from a centralized switching facility to individual businesses, organizations, and homes. Among these are a fullyredundant 1 1 protection and a partially redundant 1:N protection. 13.46 Fully redundant 1 1 protection of links 547 Optical Networks Traffic source 1 Working fiber 1 Traffic destination 1 Traffic source 2 Working fiber 2 Traffic destination 2 Traffic source N Working fiber N Traffic destination N Switch Switch Protection fiber Fig. Yoshida, A.Adams, D. Khoe, and H. Chan and T. Semiconductor light-emitting diodes (LEDs) and laser diodes are suitable for this purpose. Controlled-fracture techniques are based on score-and-break methods for cleaving Scoring fibers. Electronic compensation is based on the fact that, analogous to other forms of dispersion, PMD-induced pulse spreadingcauses intersymbol interference (ISI). Zukerman, and R. The receiver uses an InGaAs pin photodiode which has the sensitivity versus data rate shown in Fig. For example, in an mBnB code with m 1 and n 2, a binary 1 is mapped into the binary pair 10, and a binary 0 becomes 01. The spontaneous noise can be modeled as a stream of randominfinitely short pulses that are distributed all along the amplifying medium. 0 0.8 0.2 0.6 0.4 Pclad /P 1.0 03 0.4 12 01 0.2 0 04 0 11 2 4 0.6 13 02 21 23 22 32 31 41 51 6 V 8 33 42 61 65 Pcore /P Optical Fibers: Structures, Waveguiding, and Fabrication 0.8 71 81 10 1.0 12 Fig. (Reproduced with permission from Way,2 1989, IEEE.) At the receivingend, the optical signal is directly detected with a high-speed wideband InGaAs pin photodiode and reconverted to a microwave signal. Intramodal dispersion or chro0.5 36 nm matic dispersion is pulse spreading that takes place within a single mode. Agrawal, Fiber Optic Communication Systems, Wiley, Hoboken, NJ, 3rd ed., 2002. Bononi, and L.Miller, “Small-area double heterostructure AlGaAs electroluminescent diode sources for optical fiber transmission lines,” Opt. 14.15. A variety of fiber types with different performance characteristics exist for a wide range of applications. What is the structure of an optical fiber? 3475–3483, Nov. Table 5.1 Six popular fiber optic connectors with theirfeatures and applications (Photos courtesy of Mr. Frank Jaffer (SENKO GROUP) www.senko.com) Connector type Features Applications ST Uses a ceramic ferrule and a rugged metal housing. To extract the desired wavelength, a circulator is used in conjunction with the grating. 9.1 Optical fiber channel Modal distortion Attenuation GVD CNR Opticalamplifier ASE noise Optical detector Shot noise Thermal noise Amplifier noise APD gain noise Electrical analog output signal to RF receiver Basic elements of an analog link and the major noise contributors 352 9.2 Optical Fiber Communications Carrier-to-Noise Ratio In analyzing the performance of analog systems, one usually calculates the ratio ofrms carrier power to rms noise power at the input of the RF receiver following the photodetection process. These events finally allowed practical lightwave communication systems to start being fielded worldwide in 1978. Problem 9.10 gives expressions for the effects of laser clipping and ASE noise. Section 1.4 gives the basic hierarchy formultiplexing digitized information streams used on optical links, and Sec. Painchaud, “100-Gb/s DQPSK transmission: From laboratory experiments to field trials,” J. This device is used in optical amplifiers, add/drop Port 1 Port 2 multiplexers, and dispersion compensation modules. Thus, compared to a pin photodiode, the APD improves the SNR by24.7 dB. 106–125, Jan. Thus each polarization mode will travel at a slightly different group velocity and the polarization orientation will rotate with distance. Figure 9.7 depicts the technique for combining N independent messages. Consequently, the spectral width of the optical emission is very narrow. Each guided mode is a pattern of electric andmagnetic field distributions that is repeated along the fiber at equal intervals. (a) Let us first find the quantum limit in terms of the quantum efficiency of the detector and the energy of the incident photon. The boundary conditions require that the tangential components Ef and Ez of E inside and outside of the dielectric interface at r a must be thesame, and similarly for the tangential components Hf and Hz. Consider first the tangential components of E. Tables 6.1 and 6.2 list the performance values for pin and avalanche photodiodes, respectively. The information flow in the second line would then be from right to left. Johansson, and C. The signals then finally emerge from only one outputport. In addition, such a security mechanism ensures that no malicious eavesdropping threat is probable. 11.6 Optical Fiber Communications Absorption and gain spectra for erbium ions in a silica fiber doped with Ge and Al. (Modified with permission from Giles and Desurvire,20” 1991, IEEE.) Signal in Pump OI OI WSC Tap EDFA Signal out TapPump laser (a) Pump OI Signal in EDFA Tap OI Tap Pump WSC Pump EDFA Pump laser (c) Tap Signal out Pump laser (b) Signal in OI WSC WSC OI Tap Signal out Pump laser OI: Optical isolator WSC: Wavelength-selective coupler Fig. (a) Why may it be more important to encrypt information in the downstream direction in a PON and not necessarilyin the upstream path? These factors directly affect the radiative efficiency and lifetime of a light source. 13.36. 605 Optical Fiber Communications Optical fiber link or device under test BERT module Fig. Two approaches to this concept are optical burst switching (OBS) and optical packet switching (OPS). To explore this concept a little further, Eq.(2.81) shows that the number of modes that can propagate in a multimode graded-index fiber of core size a and index profile a is 2 M α 2π an1 Δ α 2 λ Thus, for example, twice as many modes propagate in a given fiber at 900 nm than at 1300 nm. Tap points at both the transmitter and the receiver, each with coupling efficiencies CT .1011–1015, June 1988. In both devices coarse tuning is achieved by manual adjustment of a high-precision adjuster and further fine tuning is achieved by means of a piezoelectric actuator. DiVita, M. This could be resolved by assigning a fixed wavelength to each optical path throughout the network, or by dropping one of the incoming channels at thenode and retransmitting it at another wavelength. 3.1 2000 4000 6000 Dose [rad (Si)] (a) 8000 10000 0 10–1 100 101 102 103 Time after irradiation (s) (b) 104 105 General trend of the effects of ionizing radiation on optical fiber attenuation. , “Experimental determination of system outage probability due to first-order and secondorder PMD,” J. Thetransmission properties of an optical waveguide are dictated by its structural characteristics, which have a major effect in determining how an optical signal is affected as it propagates along the fiber. Wang, F. 129. Example 3.6 Consider a graded-index multimode fiber for which the index profile a 2.0, the core index n1 1.480, the core-claddingindex difference Δ 0.01, and the core radius a 25 mm. 13.2 illustrates: Local Area Network (LAN) A local area network (LAN) interconnects users in a localized area such as a large room or work area, a department, a home, a building, an office or factory complex, or a small group of buildings. Ishibashi, S. 603 Circulator Tunable filter DWDMsignals PASE Control signal PD2 (a) Fig. Klonidis, and M. 2318–2330, July 2005. How much does n (T, P) vary from nair when the pressure is 640 torr and the temperature is 0 C (which would be at a higher elevation and a lower temperature)? Thus one can make some application tradeoffs when using the chirped Bragg grating for dispersioncompensation, such as 1000 ps/nm over a 1-nm bandwidth. A 10-m length of the lower grade fiber is used at each end in order to connect to transmission equipment. Kwon, M. An optical fiber thickness monitor is used in a feedback loop Optical Fibers: Structures, Waveguiding, and Fabrication 75 Precision feed mechanism Clamp Preform Drawingfurnace Bare fiber Fiber thickness monitor Elastic coating applicator Coated fiber Takeup drum Fig. Located in the express path is a device called a wavelength blocker that can be configured to block those wavelengths that are to be received at the node. Ackerman and A. However, the loss in a flattop device is usually 2 to 3 dB higher than that in agaussian AWG. The following expression18 has been derived for the effective number of modes Meff that are guided by a curved multimode fiber of radius a: M eff 2 α 2 2a 3 M 1 2α Δ R 2 n2 kR 3 (3.7) where a defines the graded-index profile, D is the core-cladding index difference, n2 is thecladding refractive index, k 2p/l is the wave propagation constant, and 112 Optical Fiber Communications M α ( n ka )2 Δ α 2 1 (3.8) is the total number of modes in a straight fiber [see Eq. (2.81)]. 2.1 The Nature of Light The concepts concerning the nature of light have undergone several variations during the history of physics. 14.5.2 Fig.11.5 Optical Fiber Communications Simplified energy-level diagrams and various transition processes of Er 3 ions in silica raise electrons into excited states. Two examples of such a device are isolators and circulators. Figure 14.5 shows a plot of the power level in a signal pulse stream as a function of time. However, it has generally been observedthat the loss increases with increasing mode number.26,33 114 3.2 Optical Fiber Communications Signal Dispersion in Fibers As shown in Fig. However, the temperature variation of Ith can be approximated by the empirical expression T T0 I th (T ) I z e (4.54) Normalized threshold current Ith (T)/Iz where T0 is a measure of the thresholdtemperature coefficient and Iz is a constant. 14.7.4 Network Maintenance An OPM taps off a small portion of the light signals in a fiber and separates the wavelengths or scans them onto a detector or detector array. This parameter is defined as the Photodiode ratio of the input SNR to the output SNR of the amplifier. 8.3. For simplicity, the receiversensitivity (in dBm) can be approximated from curve fitting by PR 11.5 1ogB – 60.5 where B is the data rate in Mb/s. Lightwave Tech., vol 24, pp. However, for a PCF the effective refractive index of the cladding depends on the wavelength and the size and pitch of the holes. Quantum E l e c t ro n . At any multiplexing level a signal at the designatedinput rate is combined with other input signals at the same rate. (a) Using this equation, show that the time required for a crack of initial depth ci to grow to its failure size cf is given by t 2 χ ( 2 b)/ 2 χ ( 2 b)/ 2 i f ( b 2) A(Y σ )b (b) For long, static fatigue times (on the order 2 b 2 b of 20 years), K i Kf for large values of b. SuitablemBnB codes for high data rates are the 3B4B, 4B5B, 5B6B, and 8B10B codes. 3.17). (13.2) through (13.6), the power budget for this link then is P 10 log 0 ( N 1) α L 2 NLc ( N 2) Lthru 2Ltap NLi P1, N [fiber connector coupler throughput ingress/egress coupler intrinsic] losses N (α L 2 Lc Lthru Li ) α L 2 Lthru 2 Ltap (13.12) The last expression shows that the losses (in decibels) of the linear bus increase linearly with the number of stations N. The fiber core has an index n0, and the material in the gap has a refractive index n1. Next, the cable assembly to be tested is connected between the launching and receiving systems, and the receivedpower level P2(l) is recorded. Wu, “Improved dynamic characteristics on SOAbased FWM wavelength conversion in lightholding SOAs,” IEEE J. Systems operating at 1550 nm provide the lowest attenuation, but the signal dispersion in a standard silica fiber is larger at 1550 nm than at 1310 nm. 1994. The period between two successive field maximain the frequency domain is called the free spectral 410 Optical Fiber Communications range (FSR) and can be represented by the relationship52 Δν FSR c ng ( ΔL d sin θ i d sin θ o ) (10.63) where qi and qo are the diffraction angles in the input and output waveguides, respectively. The most common misalignment occurring in practice, whichalso causes the greatest power loss, is axial displacement. 1875–1883, Nov. 209 IEEE Photonics Tech. 13.8). Inside the core the factor q2 is given by q2 u2 k 2l - b 2 (2.48) μ , while outside the core where k1 2p n1/l w 1 w 2 b 2 - k 22 (2.49) with k2 2p n2/l w 2μ . In addition, the resolution bandwidth must be wide enough to include theentire signal power spectrum of each modulated channel because this has a direct impact on the accuracy of the noise measurement. Bennett, Principles of Physical Optics, Wiley, New York, 2008; (e) F. This condition thus constrains the achievable bit rate, since there is a limit on how narrow a soliton pulse can be generated. 955–966, June 1996.What size dust particles are tolerable if a glass fiber having a 20-N/mm3/2 stress intensity factor is to withstand a 700-MN/m2 stress? The patterns broaden with increasing wavelength and are wider for surface emitters 165 Optical Sources Table 4.2 Typical characteristics of surface- and edge-emitting LEDs LED type Material Wavelength (nm)Operating current (mA) Fiber-coupled power (mW) Nominal FWHM (nm) SLED ELED SLED GaAlAs InGaAsP InGaAsP 850 1310 1310 110 100 110 40 15 30 35 80 150 4.2.3 Quantum Efficiency and LED Power An excess of electrons and holes in p- and n-type material, respectively (referred to as minority carriers) is created in a semiconductor lightsource by carrier injection at the device contacts. Laliotis, E. Thus it determines the spectral resolution of Collimated the OSA. Using the recurrence relations for Jν′ and Kν′ given in App. The solid acceptance angle for the fiber is therefore Ω πθ 2 π ( n12 n22 ) (2.60) For electromagnetic radiation of wavelength l emanating from a laser or awaveguide, the number of modes per unit solid angle is given by 2A/l2, where A is the area the mode is leaving or entering.28 The area A in this case is the core cross section pa2. A general state of polarization y x H E k H k E E H k z Fig. 5–11, Jan. output for a 1 pulse are bon and s on off off Let us first consider the case of a 0 pulse being sent, sothat no pulse is present at the decoding time. 13. In addition, when a high-intensity optical pulse is coupled to a fiber, the optical power modulates the refractive index seen by the optical excitation. 2.54, such ships have several large circular containers inside of them called cable tanks. Modern high-capacity telecommunication networks based onoptical fiber technology now have become an integral and indispensable part of society. Enhanced Safety Optical fibers offer a high degree of operational safety because they do not have the problems of ground loops, sparks, and potentially high voltages inherent in copper lines. A further error source is attributed to intersymbol interference (ISI),which results from pulse spreading in the optical fiber. The spectral width peak emission at 850 nm. Annovazzi-Lodi, S. 2009, www.drakaamericas.com. Equation (11.9) shows that the gain increases with device length. Typical values range from 1.4 to 4, depending on the wavelength and the pumping rate. Murata, “Recent developments in vaporphaseaxial deposition,” J. Schultz, “Fabrication of optical waveguides by the outside vapor deposition process,” Proc. Nassau, and A. (Reproduced with permission from Staring et al.,75 ” 1994, IEEE.) where Dneff is the change in the effective refractive index. 312–320, Mar./Apr. Various studies have been undertaken to extend this capability to all-opticalnetworks in which no O/E/O conversion takes place along a lightpath. The gainflattening filter (GFF) is used to equalize the gains at different wavelengths. Rainal, “Laser clipping distortion in analog and digital channels,” J. 2961–2973, Oct. Using Eq. (7.1) and solving for E, we get signaling scheme. Two commonly used doping materials for fiberlasers are erbium and neodymium. 10.23 Two parallel light-reflecting mirrored surfaces define a Fabry-Perot resonator cavity or an etalon. In designing WDM networks, transmission impairments such as chromatic and polarization-mode dispersion, optical amplifier transients, and timing jitter need to be taken into account. Karásek and F. (a) Find theinternal quantum efficiency and the internal power level. Therefore the losses are not uniform from channel to channel, since each wavelength goes through a different number of circulators and fiber gratings, each of which adds loss to that channel. In analog applications, any device nonlinearities will create frequency components in the outputsignal that were not present in the input signal. An EPON uses a 1490-nm wavelength for downstream transmission of voice and data to the ONTs and a 1310-nm wavelength for the upstream return path from an ONT to the OLT. 9.5.1 Antenna Base Station ROF Network One application of RF-over-fiber technology is in broadband wireless accessnetworks for interconnecting antenna base stations (BSs) with the central controlling office. Lobel, T. However, a nonisothermal microwave plasma operating at low pressure initiates the chemical reaction. (Reproduced with permission from Ali, Elrefaie, Wagner, and Ahmed,22 ” 1996, IEEE.) Amplifier Noise The dominant noise generated in anoptical amplifier is called amplifi ed spontaneous emission (ASE) noise. A Reed-Solomon decoder can correct up to t symbol errors, where 2t n - k. The two most popular control methods are MEMS-based and electro-optic-based techniques. 8.18 Verify the resulting expression in Eq. (8.34) for the intensity due to the combined signal and localoscillator fields. 1176–1177, Oct. van Dam, “PHASARbased WDM devices: Principles, design and applications,” IEEE J. 14.1 addresses internationally recognized measurement standards for component and system evaluations. (b) If the laser is now prebiased to a current density JB IB /A, so that the initial excess carrier pair density is nB JBt /qd,then the current density in the active region during a current pulse Ip is J JB Jp. Show that in this case Eq. (4.50) results. Mollenauer and J. 6.16 Simple diagram of a SAM APD structure (layers are not drawn to scale) Temperature Effect on Avalanche Gain The gain mechanism of an avalanche photodiode is very temperature sensitive because ofthe temperature dependence of the electron and hole ionization rates. If the link is to transport 10-Gb/s data, then the bandwidths of the fibers will determine the resulting effective maximum link length. The limiting factor on LED and laser diode lifetime is internal degradation. Han and S. 626–635, May 1988. Topics Quantum Electronics, vol. 2.4.3through 2.4.9 we first solve Maxwell’s equations for a circular step-index waveguide and then describe the resulting solutions for some of the lower-order modes. 12.10.2 Soliton Parameters Recall that the full-width half-maximum (FWHM) of a pulse is defined as the full width of the pulse at its half-maximum power level (see Fig. This allows thecreation and Inagaki,63 1980, IEEE.) of any type of array pattern (for example, closepacked arrays, a single circle surrounding a large solid core, or a star-shaped hollow core) and hole shape (for example, circular, hexagonal, or oval openings) in the final fiber. This is effective since SBS is a narrowband process. (b) Subsequent recovery as afunction of time after radiation has stopped. The service granularity can be in increments of 10 Mb/s in the 10-to-100 Mb/s service range and in increments of 100 Mb/s in th

Optical communication essentials gerd keiser pdf books free 13.5).49 13.5 Optical Add/Drop Multiplexing An optical add/drop multiplexer (OADM) is a device that allows the insertion or extraction of one or more wavelengths from a fiber at a network node. Cheng, "A new scheme of conical-wedge-shaped fiber endface for coupling between high .