Download Fiber-Optic Communication System Wavelength Bands

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Fiber-Optic Communication System
Directly modulated laser
External modulator
NRZ and RZ intensity modulation
NRZ and RZ OOK modulation
NRZ and RZ DPSK modulation
Dispersion compensating
fiber (DCF) or grating
C-band EDFA (1.530-1.565 μm)
L-band EDFA (1.565-1.625 μm)
Raman amplifier
Optical
Receiver
Optical
Transmitter
Single mode fiber (non-dispersion shifted fiber or NDSF)
Non-zero dispersion shifted fiber (NZDSF)
p-i-n photodiode
APD photodiode
Optically preamplified p-i-n
photodiode
Multiple optical signals with distinct carrier frequencies are combined onto
a single-mode fiber: wavelength division multiplexing or WDM
ELEC-863 Topics in Optical Communications
Wavelength Bands
O
E
S
C
L
U
1260 - 1360 nm - original
1360 - 1460 nm - extended
1460 - 1530 nm - short
1530 - 1565 nm - conventional
1530.33 - 1564.68 nm
195.9 THz - 191.6 THz
1565 - 1625 nm - long
1625 - 1675 nm - ultra-long
C and L bands are the most important today
DWDM (d
(dense)) used
d ffor llong hhaull and
d ultra-long
l l
haul
h l systems; channel
h
l
spacings of 50 GHz and 100 GHz
CWDM (coarse) used for metro systems; channel spacing of 200 GHz or
more (ITU G.964.2: 1530, 1550, 1570, 1590, 1610 nm)
ELEC-863 Topics in Optical Communications
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Characteristics of Fiber-Optic Communications 1
- Lasers emitting at optical frequencies from 196.4 THz (1526.44 nm) to
191.7 THz (1563.86 nm) with a channel spacing of 50 or 100 GHz
- multiple optical signals with distinct wavelengths (optical frequencies)
combined
bi d onto
t a single-mode
i l
d optical
ti l fiber
fib (wavelength
(
l
th di
division
ii
multiplexing)
- C-band erbium doped fiber amplifiers (EDFAs 1.530-1.565 μm), L-band
EDFAs (1.565-1.625 μm), Raman amplifiers
- solitary and pre-amplified InGaAsP p-i-n photodiodes and avalanche
photodiodes
- direct intensity modulation, external NRZ and RZ OOK modulation,
external NRZ and RZ DPSK modulation
- zero-dispersion wavelength of fiber is 1.31 μm, dispersion at a wavelength
of 1.55 μm is ~17 ps/km/nm (NDSF), attenuation of ~ 0.2 dB/km
- zero-dispersion wavelength of fiber is 1.47-1.51 μm, dispersion at a
wavelength of 1.55 μm is 2-4 ps/km/nm (NZDSF), attenuation of ~ 0.2 dB/km
ELEC-863 Topics in Optical Communications
Characteristics of Fiber-Optic Communications 2
- dispersion compensating fiber (DCF) (dispersion at a wavelength of 1.55 μm
is -80 ps/km/nm, attenuation is ~0.5 dB/km) or dispersion compensating
gratings compensate dispersion.
- optical amplifiers compensate loss
Net dispersion ≈ 0 ps/nm
EDFA Gain ≈ Fiber Loss
DCF
NZDSF
EDFA
EDFA
N spans for long haul, ultra-long haul, and transoceanic systems
ELEC-863 Topics in Optical Communications
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WDM Fiber-Optic Communication System
TX-1
RX-1
Optical
Fiber
TX-2
TX-3
RX-2
EDFA
….
WDM
Mux
RX-3
WDM
Demux
64 channels with 100 GHz spacing
TX-64
RX-64
…
189.7-196.0 THz,
1580.35-1529.56 nm
ELEC-863 Topics in Optical Communications
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