Volume 02 Issue 12-2022
140
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
140-144
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
A
BSTRACT
One of the most important components of optical communication systems is optical amplifiers. By
improving the performance of optical amplifiers, we will be able to achieve the optimality of the entire
network. This article describes optical amplifiers and their types.
K
EYWORDS
Optical amplifiers, SOA - Semiconductor Optical Amplifiers, EDFA
–
Erbium Doped Fiber Amplifier
I
NTRODUCTION
An optical amplifier is a device that amplifies an
optical signal directly, without the need to first
convert it to an electrical signal. An optical
amplifier may be thought of as a laser without an
optical cavity, or one in which feedback from the
cavity is suppressed [1,2,3,4]. Optical amplifiers
Journal
Website:
http://sciencebring.co
m/index.php/ijasr
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Research Article
THE WORKING PRINCIPLE OF OPTICAL AMPLIFIERS AND
THEIR TYPES
Submission Date:
December 11, 2022,
Accepted Date:
December 16, 2022,
Published Date:
December 21, 2022
Crossref doi:
https://doi.org/10.37547/ijasr-02-12-20
Odinaxon Rayimjonova
Head of the Department of Telecommunication Engineering, Tashkent University of Information
Technologies Fergana branch, Uzbekistan
Abrorjon Ismoilov
Assistant of the Department of Telecommunication Engineering, Tashkent University of Information
Technologies Fergana branch, Uzbekistan
Volume 02 Issue 12-2022
141
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
140-144
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
are important in optical communication and laser
physics. They are used as optical repeaters in the
long distance fiber-optic cables which carry much
of the world's telecommunication links.
The main part
There are several different physical mechanisms
that can be used to amplify a light signal, which
correspond to the major types of optical
amplifiers. In doped fiber amplifiers and bulk
lasers, stimulated emission in the amplifier's gain
medium causes amplification of incoming light. In
semiconductor
optical
amplifiers
(SOAs),
electron-hole recombination occurs. In Raman
amplifiers, Raman scattering of incoming light
with phonons in the lattice of the gain medium
produces photons coherent with the incoming
photons [5,6,7]. Parametric amplifiers use
parametric amplification. Almost any laser active
gain medium can be pumped to produce gain for
light at the wavelength of a laser made with the
same material as its gain medium. Such amplifiers
are commonly used to produce high power laser
systems. Special types such as regenerative
amplifiers and chirped-pulse amplifiers are used
to amplify ultrashort pulses.
Solid-state amplifiers are optical amplifiers that
uses a wide range of doped solid-state materials
(Nd: Yb:YAG, Ti:Sa) and different geometries
(disk, slab, rod) to amplify optical signals. The
variety of materials allows the amplification of
different wavelength while the shape of the
medium can distinguish between more suitable
for energy of average power scaling. Beside their
use in fundamental research from gravitational
wave detection[11] to high energy physics at the
National Ignition Facility they can also be found in
many of today’s ultra shor
t pulsed lasers.
Doped fiber amplifiers (DFAs) are optical
amplifiers that use a doped optical fiber as a gain
medium to amplify an optical signal. They are
related to fiber lasers. The signal to be amplified
and a pump laser are multiplexed into the doped
fiber, and the signal is amplified through
interaction with the doping ions.
Fig. 1. Schematic diagram of a simple Doped Fiber Amplifier
Volume 02 Issue 12-2022
142
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
140-144
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
Amplification is achieved by stimulated emission
of photons from dopant ions in the doped fiber.
The pump laser excites ions into a higher energy
from where they can decay via stimulated
emission of a photon at the signal wavelength
back to a lower energy level. The excited ions can
also
decay
spontaneously
(spontaneous
emission) or even through nonradiative
processes involving interactions with phonons of
the glass matrix. These last two decay
mechanisms compete with stimulated emission
reducing the efficiency of light amplification
[9,10,11,12]. The amplification window of an
optical amplifier is the range of optical
wavelengths for which the amplifier yields a
usable gain. The amplification window is
determined by the spectroscopic properties of the
dopant ions, the glass structure of the optical
fiber, and the wavelength and power of the pump
laser. A relatively high-powered beam of light is
mixed with the input signal using a wavelength
selective coupler (WSC). The input signal and the
excitation light must be at significantly different
wavelengths. The mixed light is guided into a
section of fiber with erbium ions included in the
core. This high-powered light beam excites the
erbium ions to their higher-energy state. When
the photons belonging to the signal at a different
wavelength from the pump light meet the excited
erbium ions, the erbium ions give up some of their
energy to the signal and return to their lower-
energy state. A significant point is that the erbium
gives up its energy in the form of additional
photons which are exactly in the same phase and
direction as the signal being amplified. So the
signal is amplified along its direction of travel
only. This is not unusual
–
when an atom "lases" it
always gives up its energy in the same direction
and phase as the incoming light. Thus all of the
additional signal power is guided in the same
fiber mode as the incoming signal. An optical
isolator is usually placed at the output to prevent
reflections returning from the attached fiber.
Such reflections disrupt amplifier operation and
in the extreme case can cause the amplifier to
become a laser. The erbium doped amplifier is a
high gain amplifier. The principal source of noise
in DFAs is Amplified Spontaneous Emission
(ASE), which has a spectrum approximately the
same as the gain spectrum of the amplifier. Noise
figure in an ideal DFA is 3 dB, while practical
amplifiers can have noise figure as large as 6
–
8
dB. As well as decaying via stimulated emission,
electrons in the upper energy level can also decay
by spontaneous emission, which occurs at
random, depending upon the glass structure and
inversion
level.
Photons
are
emitted
spontaneously in all directions, but a proportion
of those will be emitted in a direction that falls
within the numerical aperture of the fiber and are
thus captured and guided by the fiber. Those
photons captured may then interact with other
dopant ions, and are thus amplified by stimulated
emission. The initial spontaneous emission is
therefore amplified in the same manner as the
signals, hence the term Amplified Spontaneous
Emission. ASE is emitted by the amplifier in both
the forward and reverse directions, but only the
forward ASE is a direct concern to system
performance since that noise will co-propagate
with the signal to the receiver where it degrades
system performance. Counter-propagating ASE
Volume 02 Issue 12-2022
143
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
140-144
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
can, however, lead to degradation of the
amplifier's performance since the ASE can
deplete the inversion level and thereby reduce
the gain of the amplifier and increase the noise
produced relative to the desired signal gain.
Semiconductor optical amplifiers (SOAs) are
amplifiers which use a semiconductor to provide
the gain medium. These amplifiers have a similar
structure to Fabry
–
Perot laser diodes but with
anti-reflection design elements at the end faces.
Recent designs include anti-reflective coatings
and tilted wave guide and window regions which
can reduce end face reflection to less than
0.001%. Since this creates a loss of power from
the cavity which is greater than the gain, it
prevents the amplifier from acting as a laser.
Another type of SOA consists of two regions. One
part has a structure of a Fabry-Perot laser diode
and the other has a tapered geometry in order to
reduce the power density on the output facet.
Semiconductor optical amplifiers are typically
made
from
group
III-V
compound
semiconductors
such
as
GaAs/AlGaAs,
InP/InGaAs, InP/InGaAsP and InP/InAlGaAs,
though any direct band gap semiconductors such
as II-VI could conceivably be used. Such
amplifiers are often used in telecommunication
systems in the form of fiber-pigtailed
components, operating at signal wavelengths
between 850 nm and 1600 nm and generating
gains of up to 30 dB.
R
EFERENCES
1.
Райимжонова, О. С., Тажибаев, И. Б., &
Тошпулатов, Ш. М. (2021). Телевизион
тасвир сигналлари спектрини зичлаш
(сиқиш) усуллари таҳлили. Scientific
progress, 2(6), 235-244.
2.
Raimimonova, O. S., & Iskandarov, U. U.
(2020). Overview of the experimental
reasarche of open optical system for
monitoring of deviations of the buildings
with concrete products. Scientific Bulletin
of Namangan State University, 2(6), 374-
378.
3.
Rayimjonova, O. S., Yuldashev, K. T.,
Ergashev, U. S., & Jurayeva, G. F. (2020). LR
Dalibekov Photo Converter for Research of
Characteristics Laser IR Radiation.
International
Journal
of
Advanced
Research in Science, Engineering and
Technology, 7(2), 12788-12791.
4.
Raimimonova, O. S., & Nurdinova, R. A. R.
Dalibekov, Sh. M. Ergashev (2021).
Increasing the possibility of using
thermoanemometric type heat exchangers
in the control of man-madt objects.
International
Journal
of
Advanced
Research in Science, Engineering and
Technology, 8(3), 16783-89.
5.
Shipulin, Y. G., Raimzhonova, O. S.,
Ergashev, O. M., & Usmanov, Z. K. (2021).
Method
for
Ensuring
Continuous
Functioning of Multichannel Systems for
Control and Recording of Water
Composition in Seismic Wells.
6.
Kadirov, O. K. Yu. G., Shipulin, AA
Kakhkharov.(2019). The Multipurpose
converter for control of Parameters of
Volume 02 Issue 12-2022
144
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
140-144
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
Gaseous Environments. International
Journal of Advanced Research in Science,
Engineering and Technology, 6(5), 9155-
60.
7.
Yuldashev, K. T. (2020). Research
photoelectric
and
photographic
characteristics of the converter of the
image of the ionization type. Scientific
Bulletin of Namangan State University,
2(10), 16-22.
8.
Yuldashev, K. T., & Akhmedov, S. S. (2021).
Physical properties at the contact
semiconductor-Gas discharge plasma in a
thin gas discharge cell. Asian Journal of
Multidimensional Research, 10(9), 569-
573.
9.
Юсупов, Ш. А. (2009). Диагностическая
значимость
ультразвуковой
сонографии при аппендикулярных
перитонитах у детей. Сибирский
медицинский журнал (Иркутск), 86(3),
138-141.
10.
Yuldashev, H. T., & Mirzaev, S. Z. (2021).
Investigation of background radiation and
the possibility of its limitation in a
semiconductor
ionization
system.
ACADEMICIA:
An
International
Multidisciplinary Research Journal, 11(4),
1364-1369.
11.
Yuldashev, K. T., Akhmedov, S. S., &
Ibrohimov, J. M. (2020). Damping cell from
gallium arsenide with plasma contacts in
an extreme gas discharge cell. Journal of
Tashkent Institute of Railway Engineers,
16(1), 36-41.
12.
Fayzullaev, N. I., Akmalaev, K. A., Karjavov,
A., Akbarov, H. I., & Qobilov, E. (2020).
Vapor phase catalytic hydratation of
acetylene. ACADEMICIA: An International
Multidisciplinary Research Journal, 10(7),
88-98.
