The key
component advances are summarized in Table 8.1.
Fiber and WDM 199
Figure 8.1 Multimode fiber (MMF) overview
O-Band
5
1.0
0.5
0.2
Fiber loss (dB/km)
600 nm 1000 nm 1400 nm 2200 nm
Sample Multimode Fiber (MMF) Spectrum
Source
(LED, laser)
Multimode Fiber (MMF) Design
Cladding
Transmit power distributed across hundreds
of modes (high modal-dispersion)
50-62.5 ?µm
125 ?µm Core
Figure 8.2 Single-mode fiber (SMF) overview
Source
(LED, laser)
Single-Mode Fiber (SMF) Design
Cladding
Transmit power distributed across
very few modes (~3%)
125 ?µm Core
8-10 ?µm
O-Band
5
1.0
0.5
0.2
Fiber loss (dB/km)
1300 nm 1400 nm 1500 nm 1600 nm
Sample Single-Mode Fiber (SMF) Spectrum
SONET, Ethernet
(1310 nm)
E-Band
SMF ???water-peak???
S-Band
CWDM
(20 nm, G.694.2)
C- & L-Bands
DWDM (1.6, 0.8, 0.4, 0.2 nm)
G.694.1
???Low-waterpeak???
fibers
200 Chapter 8
Component Function Technologies Maturity Cost
Fixed lasers Transmitters, pump
EDFA, and Raman
amplifi ers
DFB, external modulation Very high High
Tunable lasers Transmitters, pump
EDFA, and Raman
amplifi ers
External cavity laser, tunable
VCSEL, two/three-section DBR,
laser arrays
Medium High
Amplifi ers Regenerate optical
signals
Erbium doped fi ber/waveguide
amp (EDFA, EDWA), Raman
High High
Fixed fi lters Multiplex/demultiplex
wavelengths, equalize
gain, remove noise
Thin fi lm, arrayed waveguide
grating, Bragg grating
High Low
Tunable fi lters Multiplex/demultiplex
wavelengths, equalize
gain, remove noise
Fabry-Perot, Mach Zender
interferometer, acousto-optic
Medium Medium
Optical switches Lightpath routing,
protection switching
MEMS, liquid crystal, lithium
niobate, SOA, bubble-jet
Medium-low High
TABLE 8.
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