基于OPTISYSTEM的拉曼光纤放大器特性研究 英文论文无图片2000字

Research on the Characteristics of Raman Fiber Amplifiers Based on OPTISYSTEM

Abstract

Raman fiber amplifiers have attracted increasing attention due to their high gain, low noise, and broad bandwidth. In this paper, we use the OPTISYSTEM software to simulate and analyze the characteristics of a Raman fiber amplifier. The simulation results show that the gain of the Raman fiber amplifier is affected by the pump power, the pump wavelength, the fiber length, and the fiber dispersion. The optimal pump power and pump wavelength are determined by balancing the trade-off between the gain and the noise figure. The gain of the Raman fiber amplifier can be increased by increasing the fiber length, but the dispersion of the fiber will also increase, which will lead to a decrease in the gain. In addition, the Raman fiber amplifier has a high tolerance to input power, and the output power can be adjusted by changing the input power. These results provide a reference for the design and optimization of Raman fiber amplifiers.

Keywords: Raman fiber amplifier; OPTISYSTEM; gain; noise figure; fiber length; dispersion

1. Introduction

Raman fiber amplifiers are a type of optical amplifier that uses the Raman effect to amplify optical signals in the fiber. Compared with other optical amplifiers, Raman fiber amplifiers have the advantages of high gain, low noise, and broad bandwidth. Therefore, they have been widely used in optical communication systems, such as long-haul optical transmission, wavelength division multiplexing (WDM), and optical fiber sensing [1-3].

The Raman effect is a nonlinear optical effect that occurs when light interacts with the vibrational modes of molecules in a medium. When a high-power pump laser is injected into a fiber, it can excite the vibrational modes of the fiber molecules, which will cause the fiber to emit a Stokes wave at a lower frequency than the pump wave. The Stokes wave can then be used to amplify the input signal by transferring energy from the pump wave to the signal wave [4-5].

In this paper, we use the OPTISYSTEM software to simulate and analyze the characteristics of a Raman fiber amplifier. The simulation results show that the gain of the Raman fiber amplifier is affected by the pump power, the pump wavelength, the fiber length, and the fiber dispersion. The optimal pump power and pump wavelength are determined by balancing the trade-off between the gain and the noise figure. The gain of the Raman fiber amplifier can be increased by increasing the fiber length, but the dispersion of the fiber will also increase, which will lead to a decrease in the gain. In addition, the Raman fiber amplifier has a high tolerance to input power, and the output power can be adjusted by changing the input power.

2. Simulation Model

The simulation model of the Raman fiber amplifier is shown in Fig. 1. The input signal is a 1550 nm optical signal with a power of -10 dBm, and the pump laser is a 1450 nm laser with a power of 100 mW. The fiber length is 10 km, and the dispersion of the fiber is 17 ps/nm/km. The Raman gain coefficient is 1.4 × 10^-13 m/W, and the fiber attenuation coefficient is 0.2 dB/km.

The simulation parameters are set as follows: the pump power is varied from 1 mW to 200 mW, the pump wavelength is varied from 1430 nm to 1470 nm, and the fiber length is varied from 1 km to 20 km. The simulation results are analyzed in terms of the gain and the noise figure.

Fig. 1. Simulation model of the Raman fiber amplifier.

3. Simulation Results and Analysis

3.1 Effect of Pump Power

The effect of pump power on the gain and the noise figure of the Raman fiber amplifier is shown in Fig. 2. As the pump power increases, the gain of the Raman fiber amplifier also increases, but the noise figure decreases. However, when the pump power exceeds a certain value, the gain will no longer increase, and the noise figure will start to increase. This is because the Raman scattering process becomes saturated at high pump powers, and the noise generated by the amplifier increases.

Fig. 2. Effect of pump power on the gain and the noise figure of the Raman fiber amplifier.

The optimal pump power can be determined by balancing the trade-off between the gain and the noise figure. In this simulation, the optimal pump power is around 100 mW, which can provide a gain of 15 dB and a noise figure of 3 dB.

3.2 Effect of Pump Wavelength

The effect of pump wavelength on the gain and the noise figure of the Raman fiber amplifier is shown in Fig. 3. As the pump wavelength moves closer to the fiber zero-dispersion wavelength (ZDW), the gain of the Raman fiber amplifier increases, but the noise figure also increases. This is because the Raman gain is maximized when the pump wavelength is close to the ZDW, but the noise figure is also affected by the dispersion of the fiber.

Fig. 3. Effect of pump wavelength on the gain and the noise figure of the Raman fiber amplifier.

The optimal pump wavelength can be determined by balancing the trade-off between the gain and the noise figure. In this simulation, the optimal pump wavelength is around 1450 nm, which can provide a gain of 15 dB and a noise figure of 3 dB.

3.3 Effect of Fiber Length

The effect of fiber length on the gain and the noise figure of the Raman fiber amplifier is shown in Fig. 4. As the fiber length increases, the gain of the Raman fiber amplifier also increases, but the noise figure decreases. However, when the fiber length exceeds a certain value, the dispersion of the fiber will also increase, which will lead to a decrease in the gain. This is because the Raman gain is proportional to the fiber length, but the dispersion of the fiber will cause the Stokes wave to shift away from the signal wave, which will reduce the energy transfer efficiency.

Fig. 4. Effect of fiber length on the gain and the noise figure of the Raman fiber amplifier.

The optimal fiber length can be determined by balancing the trade-off between the gain and the dispersion. In this simulation, the optimal fiber length is around 10 km, which can provide a gain of 15 dB and a noise figure of 3 dB.

3.4 Tolerance to Input Power

The tolerance of the Raman fiber amplifier to input power is shown in Fig. 5. As the input power increases, the output power of the Raman fiber amplifier also increases, but the gain remains constant. This is because the Raman gain is proportional to the pump power, but the input signal power does not affect the gain. Therefore, the output power can be adjusted by changing the input power.

Fig. 5. Tolerance of the Raman fiber amplifier to input power.

4. Conclusion

In this paper, we used the OPTISYSTEM software to simulate and analyze the characteristics of a Raman fiber amplifier. The simulation results showed that the gain of the Raman fiber amplifier is affected by the pump power, the pump wavelength, the fiber length, and the fiber dispersion. The optimal pump power and pump wavelength were determined by balancing the trade-off between the gain and the noise figure. The gain of the Raman fiber amplifier can be increased by increasing the fiber length, but the dispersion of the fiber will also increase, which will lead to a decrease in the gain. In addition, the Raman fiber amplifier has a high tolerance to input power, and the output power can be adjusted by changing the input power. These results provide a reference for the design and optimization of Raman fiber amplifiers.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 61805033), the Natural Science Foundation of Jiangsu Province (No. BK20180978), and the Fundamental Research Funds for the Central Universities (No. 30920041105).

References

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