SOA are similar to lasers in their construction and functioning principle but with one fundamental difference. SOA amplifiers contain antireflex layer against creation of resonance and the signal accumulation within the medium.
During construction the most important thing is the choice of a semiconductor material with good quantum efficiency. Quantum efficiency is defined as a ratio between maximal amount of generated photons to the number of excited charges of the carrier [ 16 ].
Among applicable elements for the construction are the following: arsenic As , gallium Ga , aluminium Al , indium In , and phosphor P. Stimulated emission precedes stimulated absorption which happens when the absorbed energy is passed on to the electron in a higher valence band of the semiconductor because of the subsequent excitation of that electron to a higher energy level in conductivity band.
Excitation of the medium happens as a result of the current of electric energy in our case via electrode connected to the semiconductor. In case of a considerable electron population being on the higher energy level, a population inversion is made.
It is a base for the stimulated emission of more photons [ 16 — 18 ]. Photons radiated at stimulated emission are highly coherent and have the same direction and phase as the stimulating ray. The principle of the stimulated emission and population inversion can be seen in Figure 6.
Because of simple integration of the amplifier into the receiver, the SOA is often used as a preamplifier when the signal is amplified just before it reaches the receiver. In the same way APD Avalanche Photodiode adds additional noise to the signal; the preamplifiers degrade the SNR spacing thanks to the noise of the spontaneous emission.
Although the SOA can be used to amplify several channels simultaneously, their greater usage in WDM is hampered by their basic problem of relatively quick response. In the ideal case the signal from individual channels is amplified with constant gain [ 13 , 18 ].
Parameters like sensitivity, nonlinear effects, polarization, and high junction losses make these amplifiers harder to use than the in-line amplifiers. But the EDFA has proved to be more preferable to amplify the signal in the fully optical communication systems thanks to their better parameters.
They are often used as a cheaper option of the optical amplifiers in metropolitan optical networks. As DWDM standard is still being developed and there is compressing of individual channels, it is necessary to prevent FWM Four-Wave Mixing and select appropriate spacing between the channels.
Ahmed et al. When using Ivaniga et al. The results obtained in the article were used for setting of broadcast channels, and NRZ code was used for better error rate [ 20 ]. Pump current for SOA has been selected on the basis of achieved results [ 21 ]. BER ranged from to.
From the results published in this article SOA amplifier was designed in order to reach the best error rate for particular wavelengths [ 21 ]. The EDFA parameter settings and the length of erbium doped fibre have been designed on the basis of [ 22 ]. Obtained results helped to design individual components [ 22 ]. Olonkins et al. Anderson compared optical amplifiers in terms of location in the transmission path.
The comparison of optical amplifiers was based on the location of optical communication systems, in which EDFA and SOA were used as booster in our simulation. In the topology there are three junction lines. The red junction represents the optical signal, the blue one represents electrical signal, and the green junction illustrates the logical signal [ 26 — 28 ].
The whole optical communication system contains 4 transmission lines. Every optical transmitter contains 4 basic blocks. The logic signal enters the electrical generator. In Figure 7 it is shown as Channel 1 and Channel 2, respectively. It is noteworthy that its inversion has a tendency to reach the peak in the middle of EDFA where the pump is the least distressed. Figures 8 d and 8 e are the forward- and backward-band power solutions for the respective four-channel WDM system. SOA model provides many options for modelling of semiconductor amplifier.
In our case, we have used the parabolic model where has the value of 0. The gain includes the carrier-density dependence of the peak gain wavelength and the quadratic dependence on the wavelength.
This approach is very common one for dealing with an SOA spectral gain dependence. Download Now. Start networking and exchanging professional insights Register now or log in to join your professional community. Upvote 0 Views Followers 2. Write an Answer Register now or log in to answer. Dear Ehab, Thank you for asking me this question. I hope this answers your inquiry. In connection with the service of Pan Dacom Direkt, we can offer our customers tailor-made services at attractive prices.
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The transmission takes place in up to 16 channels with wavelengths between nm and nm. DWDM Dense Wavelength Division Multiplexing is an optical multiplexing technology with the enormous performance for more than 10 Tbps and allows the use of 96 wavelengths in the optical C-band only as well as long-haul amplification. This protects the investment in the existing CWDM networks. The time division multiplex transmits several signals or connections at different times and is ideal for the aggregation of lower data rates for the optimized use of xWDM systems.
Amplifier Booster to increase the output power at the beginning of the link. Inline-Amplifier to compensate the attenuation of the link. Light sources for optical communication in the 1. However, SOAs are required as pre-amplifiers to counter attenuation in the communication light when performing long-distance transmission. Optical Communication. Related Links Optical Communication. Optical Sensing for Industry. Optical Sensing for Medicine.
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