**4. Propagation and amplification of SOA and FRA**

The result of SOA is depicted in **Figure 12**. The BER can be discussed by applying a model and simulation using a computer. A propagation model and data source mode are simply considered; the BER can be calculated analytically as well. If the device for BER analysis is not available, OTDR can be applied to detect the wave losses through the OptiSystem software for detecting the BER. A schematic flowchart of **Figure 10** is depicted to this analysis. BER is found in SOA where 1350 nm wavelength with 1 mW input power is better than the others since it has higher energy than 1470 nm and 1560 nm, so that BER oscillation depends on energy. However, after about 150 km, BER value increases. It is not surprising when the distance is long then the error will come; this is due to attenuation of geometry length where it can operate either low- or high-energy sources corresponding to wavelength source. Even at 120 km, the highest BER is achieved for 1350 nm (highest energy). This is the weaknesses of SOA characteristics. Although these data are unknown source of loss factors, improving BER may be measured by choosing strong signal, a slow and robust modulation pattern, or line coding signal such as repetitive forward error correction program (**Figure 13**).

wavelength of 1350 nm, the dispersion is more than the wavelength of 1560 nm, but Q-factor oscillation is low. Unlike SOA, FRA has good performance for both BER and Q-factor. The result of FRA for BER and Q-factor is depicted in **Figures 14** and **15**. BER is less fluctuated and more stable for higher energy of *E = hf*, where f is frequency source, *h* is Planck constant, and *E* is energy. From 60 to 140 km, BER is nearly constant for various wavelength sources; hence this BER is better than SOA. Q-factor is faster for a stable condition at higher energy at 80 km

Optical Amplifiers for Next-Generation Telecommunication

http://dx.doi.org/10.5772/intechopen.79941

93

**Figure 16** is an eye pattern diagram with no amplifier. It is generally seen that the amplitude and bit error rate differ greatly at the lower distances at (a) than (b). The weakness of the unfocused amplitude is due to the power and geometry of the far wave from the wave source.

In **Figure 17**, both wavelengths at 160 km distance have a low Q-factor especially at lowwave energy. SOA function is very effective at a distance less than 100 km, but at the peak of 160 km, the wave amplitude is not focused anymore. Amplitude is affected by distance even

The red line facing below is BER, and the red line facing the top is Q-factor.

and continues after 160 km.

**Figure 13.** Q-factor of SOA.

if SOA is used.

**Figure 14.** BER for FRA profile.

As well as BER of SOA, Q-factor of SOA goes down as the distance is increased. But, Q-factor for 1350 nm (highest energy) is even less decayed than the others. Although the decay trends are stable beginning from 80 km similar to a constant Q-factor, at 140 km, the energy source is not good enough to maintain the oscillation source; hence the decay goes down near linear including 1350 nm and keeps maintaining to reduce it slowly. This performance shows that at

**Figure 12.** BER for SOA.

**Figure 13.** Q-factor of SOA.

wavelength of 1350 nm, the dispersion is more than the wavelength of 1560 nm, but Q-factor oscillation is low. Unlike SOA, FRA has good performance for both BER and Q-factor. The result of FRA for BER and Q-factor is depicted in **Figures 14** and **15**. BER is less fluctuated and more stable for higher energy of *E = hf*, where f is frequency source, *h* is Planck constant, and *E* is energy. From 60 to 140 km, BER is nearly constant for various wavelength sources; hence this BER is better than SOA. Q-factor is faster for a stable condition at higher energy at 80 km and continues after 160 km.

**Figure 16** is an eye pattern diagram with no amplifier. It is generally seen that the amplitude and bit error rate differ greatly at the lower distances at (a) than (b). The weakness of the unfocused amplitude is due to the power and geometry of the far wave from the wave source. The red line facing below is BER, and the red line facing the top is Q-factor.

In **Figure 17**, both wavelengths at 160 km distance have a low Q-factor especially at lowwave energy. SOA function is very effective at a distance less than 100 km, but at the peak of 160 km, the wave amplitude is not focused anymore. Amplitude is affected by distance even if SOA is used.

**Figure 14.** BER for FRA profile.

**Figure 12.** BER for SOA.

play an important role are the bit error rate (BER) and Q-factor. According to the rules of the International Telecommunication Union (ITU-T G.691; ITU-T G.692; ITU-T G.693), the BER requirements for optical communication systems must be better than 10−12, meaning that the minimum value of BER system should be smaller than 10−<sup>12</sup>. Q-factor is a quality factor that will determine the quality of a link. In a fiber-optic communication system, the minimum size of a good Q-factor is 6. The power consumption of the amplifier will be measured using the optical power meter contained in the circuit. We will then see the influence of the wavelength

The result of SOA is depicted in **Figure 12**. The BER can be discussed by applying a model and simulation using a computer. A propagation model and data source mode are simply considered; the BER can be calculated analytically as well. If the device for BER analysis is not available, OTDR can be applied to detect the wave losses through the OptiSystem software for detecting the BER. A schematic flowchart of **Figure 10** is depicted to this analysis. BER is found in SOA where 1350 nm wavelength with 1 mW input power is better than the others since it has higher energy than 1470 nm and 1560 nm, so that BER oscillation depends on energy. However, after about 150 km, BER value increases. It is not surprising when the distance is long then the error will come; this is due to attenuation of geometry length where it can operate either low- or high-energy sources corresponding to wavelength source. Even at 120 km, the highest BER is achieved for 1350 nm (highest energy). This is the weaknesses of SOA characteristics. Although these data are unknown source of loss factors, improving BER may be measured by choosing strong signal, a slow and robust modulation pattern, or line

coding signal such as repetitive forward error correction program (**Figure 13**).

As well as BER of SOA, Q-factor of SOA goes down as the distance is increased. But, Q-factor for 1350 nm (highest energy) is even less decayed than the others. Although the decay trends are stable beginning from 80 km similar to a constant Q-factor, at 140 km, the energy source is not good enough to maintain the oscillation source; hence the decay goes down near linear including 1350 nm and keeps maintaining to reduce it slowly. This performance shows that at

on the maximum transmission distance of the system.

92 Telecommunication Networks - Trends and Developments

**4. Propagation and amplification of SOA and FRA**

**Figure 15.** Q-factor of FRA profile for various energy.

**Figure 18** is somewhat different than SOA. FRA has a more effective BER and Q-factor. At a distance of less than 90 km, the very sharp eye pattern at 1350 nm wavelength is almost equal to the 1560 nm wavelength. The value of FRA at a distance of 170 km is still more effective than on SOA values both at 1350 nm and at 1560 nm. However at 1560 nm, BER is more sharp as Q-factor as well. BER and Q-factor at 1560 are higher so that the amplifier function is weak especially at great distances.

or −116.74 dB at a distance of 95 km and 3.51 × 10−<sup>9</sup>

a distance of 85 km and 1.66 × 10−<sup>9</sup>

80 km for the 1560 nm wavelength.

be used if it has a number below that value.

80 km and 3.56 × 10−<sup>9</sup>

BER value for an optical source with a wavelength of 1470 nm is 1.64 × 10−13 or −127.85 dB at

**Figure 17.** (a) SOA (BER and Q-factor) 1350 nm, 80 km. (b) SOA (BER, Q-factor) 1560 nm, 160 km.

for an optical source with a wavelength of 1560 nm is 1.26 × 10−12 or −119 dB at a distance of

4.1 that the maximum transmission distance of the fiber-optic communication system without the amplifier is 95 km for the 1350 nm wavelength, 85 km for the 1470 nm wavelength, and

In addition to the BER value, Q-factor is one of the parameters used as a reference in determining the quality of the optical circuit. Under the rules of ITU (International Telecommunication Union) in ITU-T G.691; ITU-T G.692; ITU-T G.693, it is agreed that the minimum Q-factor value that must be possessed by an optical communication system is 6. This shows that a circuit can be categorized well if the circuit has a Q-factor above 6. In contrast, the circuit cannot

Based on the simulation that has been executed, it obtains that the value of Q-factor at the source wavelength of 1350 nm is 6.59 at a distance of 95 km and 5.79 at a distance of 100 km. At the source wavelength of 1470 nm, the obtained value is 7.28 at a distance of 85 km and 5.91 at a distance of 90 km, while at the wavelength of 1560 nm, the found value is 6.32 at a

**Figure 18.** (a) Raman (BER and Q-factor) 1350 nm, 90 km. (b) Raman (BER and Q-factor) 1350 nm, 170 km.

or −84.55 dB at a distance of 100 km. The

Optical Amplifiers for Next-Generation Telecommunication

http://dx.doi.org/10.5772/intechopen.79941

95

or −87.80 dB at a distance of 90 km, whereas the BER value

or −84.49 dB at a distance of 85 km. So it can be concluded from Figure
