"Introduction". In: Fiber-Optic Communication Systems

482 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS The SNR is obtained by dividing the average signal power by the average noise power. ...

10.2. MODULATION FORMATS 483 Figure 10.2: ASK, PSK, and FSK modulation formats for a specific bit pattern shown on the top. 10.2 ...

484 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS invariably occur when the amplitudeAs(or the power) is changed by modulating the curr ...

10.2. MODULATION FORMATS 485 a single waveguide can be used. The phase shiftδφoccurring while the CW signal passes through the w ...

486 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS PSK modulation such that the carrier phase increases or decreases linearly over the b ...

10.3. DEMODULATION SCHEMES 487 Figure 10.3: FM response of a typical DFB semiconductor laser exhibiting a dip in the frequency r ...

488 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS Figure 10.4: Block diagram of a synchronous heterodyne receiver. 10.3.1 Heterodyne Sy ...

10.3. DEMODULATION SCHEMES 489 Figure 10.5: Block diagram of an asynchronous heterodyne receiver. using anenvelope detector, fol ...

490 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS Figure 10.6: (a) Dual-filter FSK and (b) DPSK asynchronous heterodyne receivers. sche ...

10.4. BIT-ERROR RATE 491 whereIp≡ 2 R(PsPLO)^1 /^2 takes valuesI 1 orI 0 depending on whether a 1 or 0 bit is being detected. Co ...

492 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS bandwidth and the operating wavelength. Furthermore,ηis also set to 1 so that the sen ...

10.4. BIT-ERROR RATE 493 Table 10.1 Sensitivity of synchronous receivers Modulation Format Bit-Error Rate Np N ̄p ASK heterodyne ...

494 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS Figure 10.7: Bit-error-rate curves for various modulation formats. The solid and dash ...

10.4. BIT-ERROR RATE 495 where P( 0 / 1 )= ∫ID 0 p(I,I 1 )dI, P( 1 / 0 )= ∫∞ ID P(I,I 0 )dI. (10.4.15) The notation is the same ...

496 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS branches of the dual filter receiver, where both of them include noise currents throu ...

10.5. SENSITIVITY DEGRADATION 497 Table 10.2 Sensitivity of asynchronous receivers Modulation Format Bit-Error Rate Np N ̄p ASK ...

498 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS 10.5.1 Phase Noise An important source of sensitivity degradation in coherent lightwa ...

10.5. SENSITIVITY DEGRADATION 499 Figure 10.8: Receiver sensitivityN ̄pversus∆ν/Bfor asynchronous ASK and FSK heterodyne receive ...

500 CHAPTER 10. COHERENT LIGHTWAVE SYSTEMS Figure 10.9: Schematic of a multiport phase-diversity receiver. are added. Moreover, ...

10.5. SENSITIVITY DEGRADATION 501 Figure 10.10: Power penalty versus RIN for several values of the local-oscillator power. Figur ...