"Introduction". In: Fiber-Optic Communication Systems

342 CHAPTER 8. MULTICHANNEL SYSTEMS filters can be tuned using thermo-optic tuning [38]. Micromechanical tuning has also been us ...

8.2. WDM COMPONENTS 343 terferometers, such as theSagnacandMichelson interferometers, can also be used to realize transmission f ...

344 CHAPTER 8. MULTICHANNEL SYSTEMS and can be accomplished in a switching time of less than 10μs. Acousto-optic tunable filters ...

8.2. WDM COMPONENTS 345 Figure 8.9: Grating-based demultiplexer making use of (a) a conventional lens and (b) a graded- index le ...

346 CHAPTER 8. MULTICHANNEL SYSTEMS Figure 8.10: Layout of an integrated four-channel waveguide multiplexer based on Mach– Zehnd ...

8.2. WDM COMPONENTS 347 Figure 8.11: Schematic of a waveguide-grating demultiplexer consisting of an array of wave- guides betwe ...

348 CHAPTER 8. MULTICHANNEL SYSTEMS Figure 8.12: (a) A generic add–drop multiplexer based on optical switches (OS); (b) an add– ...

8.2. WDM COMPONENTS 349 Several kinds of add–drop filters have been developed since the advent of WDM technology [84]–[94]. The ...

350 CHAPTER 8. MULTICHANNEL SYSTEMS Figure 8.13: (a) Two designs of add–drop multiplexers using a single optical circulator in c ...

8.2. WDM COMPONENTS 351 Figure 8.15: A star coupler formed by using the fused biconical tapering method. Several kinds of star c ...

352 CHAPTER 8. MULTICHANNEL SYSTEMS Figure 8.16: (a) Schematic illustration of a wavelength router and (b) its implementation us ...

8.2. WDM COMPONENTS 353 difference∆Lbetween two neighboring waveguides remains constant from one wave- guide to next. The phase ...

354 CHAPTER 8. MULTICHANNEL SYSTEMS Figure 8.17: Schematic of an optical cross-connect based on optical switches. 8.2.6 Optical ...

8.2. WDM COMPONENTS 355 Figure 8.18: Scanning electron micrograph of an 8×8 MEMS optical switch based on free- rotating micromir ...

356 CHAPTER 8. MULTICHANNEL SYSTEMS (a) (b) Figure 8.19: Examples of optical switches based on (a) Y-junction semiconductor wave ...

8.2. WDM COMPONENTS 357 its low-cost potential (bubble-jet technology is used routinely for printers) but requires a careful des ...

358 CHAPTER 8. MULTICHANNEL SYSTEMS Figure 8.20: Four schemes for wavelength conversion: (a) optoelectronic regenerator; (b) gai ...

8.2. WDM COMPONENTS 359 beams are present simultaneously, all 1 bits are directed toward the bar port because of the refractive- ...

360 CHAPTER 8. MULTICHANNEL SYSTEMS to be changed is injected into a tunable laser directly. The change in the laser threshold r ...

8.2. WDM COMPONENTS 361 Figure 8.21: Schematic of a WDM laser made by integrating an AWG inside the laser cavity. (After Ref. [1 ...