Download Field Guide to Optical Fiber Technology (SPIE Field Guide Vol. FG16) PDF

TitleField Guide to Optical Fiber Technology (SPIE Field Guide Vol. FG16)
Author
LanguageEnglish
File Size15.5 MB
Total Pages128
Document Text Contents
Page 2

Optical Fiber
Technology

Field Guide to

Rüdiger Paschotta

SPIE Field Guides
Volume FG16

John E. Greivenkamp, Series Editor

Bellingham, Washington USA

Page 64

Optical Fiber Technology: Passive Fibers for Data Transmission




53

Important Standards for Telecom Fibers

The table below gives an overview on important
standards for telecom fibers as developed by the
International Telecommunications Union (ITU) (see
http://www.itu.int/):


Name Title

G.650.1
(06/04)

Definitions and test methods for linear,
deterministic attributes of single-mode
fiber and cable

G.651
(02/98)

Characteristics of a 50/125 μm multimode
graded-index optical fiber cable

G.651.1
(07/07)

Characteristics of a 50/125 μm multimode
graded-index optical fiber cable for the
optical access network (pre-published)

G.652
(06/05)

Characteristics of a single-mode optical
fiber and cable

G.653
(12/06)

Characteristics of a dispersion-shifted
single-mode optical fiber and cable

G.654
(12/06)

Characteristics of a cut-off shifted single-
mode optical fiber and cable

G.655
(03/06)

Characteristics of a non-zero dispersion-
shifted single-mode optical fiber and
cable

G.656
(12/06)

Characteristics of a fiber and cable with
non-zero dispersion for wideband optical
transport

G.657
(12/06)

Characteristics of a bending loss
insensitive single-mode optical fiber and
cable for the access network

Page 65

Optical Fiber Technology: Passive Fibers for Data Transmission



54

Polarization Mode Dispersion

Even fibers with rotationally symmetric design exhibit
some random birefringence due to imperfections and
bending. This polarization mode dispersion (PMD)
leads not only to random changes of the polarization state
of light, but also to pulse broadening. Even complete
temporal separation of polarization components can occur,
and such effects can limit the data rate of a telecom
system.

The broadening (or splitting) occurs because the group
delay of some fiber span depends on the input
polarization. The difference of group delay between the
two principal states of polarization is called the
differential group delay (DGD). It would be difficult to
ensure that the input corresponds to a principal state of
polarization, because the principal states and the
polarization changes are generally wavelength-dependent,
and they can also change with time, e.g., as a result of
temperature changes. For broadband signals, PMD can
introduce a pulse chirp similar to that which occurs due to
chromatic dispersion. In that way, complicated pulse
shape distortions can arise.

For fiber sections with a length of at most a few meters,
the DGD evolves in proportion to the fiber length. For
much longer lengths, the birefringence axis of the fiber
changes randomly, and the r.m.s. value of the DGD scales
only with the square root of the fiber length. Note,
however, that the actual DGD can be strongly
wavelength-dependent, and for some wavelengths, it can
be well above the r.m.s. value. For such reasons, the
average degree of pulse broadening in a telecom system
by PMD should usually not be more than a few percent of
the signal pulse duration.

The full description of PMD and its effects requires rather
sophisticated mathematics, involving frequency-
dependent Jones matrices and statistical methods.

Page 127

116
Index



pulsed fiber lasers, 93
pump cladding, 77
pump couplers, 69

Q switching, 93

Raman amplifiers, 46
Raman scattering, 32, 46
rare-earth-doped fibers,

74
refractive index, 56

saturation energy, 89
saturation power, 88
second-order dispersion,

26
self-focusing, 32, 85
self-phase modulation

(SPM), 32–35
self-similar parabolic

pulse evolution, 42
self-steepening, 33
shape birefringence, 30
silica glass, 17
silicate glasses, 74, 76
similariton fiber lasers,
95
similariton pulse

propagation, 95
single-mode fibers, 9
single-polarization

fibers, 31
soliton compression, 41
soliton fiber lasers, 94
soliton pulses, 37
splicing of fibers, 63
step-index fibers, 1, 8
stimulated Brillouin

scattering (SBS), 48

stimulated Raman
scattering (SRS), 46

stress birefringence, 30
stretched-pulse fiber

lasers, 94
subwavelength fibers, 19
supercontinuum

generation, 57

telecom fibers, 50, 53
telecom windows, 49
third-order dispersion

(TOD), 26
thulium energy levels,
92
transmission fibers, 49
transmission losses, 21
two-photon absorption,
32

ultrashort pulses, 94
upconversion fiber

lasers, 92

V number, 8, 10

wavebreaking-free fiber

lasers, 95
waveguide dispersion, 24
waveguiding, principle

of, 1
wavelength regions for

data transmission, 49

ytterbium-doped fiber

amplifiers, 84

zero-dispersion

wavelength, 27

Page 128

Rüdiger Paschotta is an expert in
lasers and amplifiers, nonlinear optics,
fiber technology, laser pulses, and
noise in optics. He started his scientific
career in 1994 with a PhD thesis in the
field of quantum optics, and thereafter
focused on applied research, covering a
wide range of laser-related topics. He

is the author or coauthor of over 100 scientific journal
articles, over 120 international conference presentations,
and several book chapters. He is also the author of the
well-known Encyclopedia of Laser Physics and
Technology. His successful academic career includes his
habilitation at ETH Zürich and his attainment of the
Fresnel Prize of the European Physical Society in 2002.

In 2004, Dr. Paschotta started RP Photonics Consul-
ting GmbH, a technical consulting company based in
Zürich, Switzerland (http://www.rp-photonics.com). He
now serves companies in the photonics industry
worldwide, working out feasibility studies and designs for
lasers and other photonic devices, identifying and solving
technical problems, finding suitable laser sources for
specific applications, and performing staff training
courses on specialized subjects. His work combines his
extensive physics knowledge, his experience with an
inventory of numerical modeling tools, a practically
oriented mind, and a passion for constructive, interactive
teamwork.

Similer Documents