Bidirectional homologous coherent microwave optical fiber stable-phase transmission method

Abstract

The invention discloses a bidirectional homologous coherent microwave optical fiber stable-phase transmission method. A bidirectional homologous coherent microwave optical fiber stable-phase transmission system using the method comprises front-end equipment and rear-end equipment; the front-end equipment and the rear-end equipment are connected through a double-core optical fiber and are used forrespectively transmitting uplink and downlink optical signals; a stationary phase reference source is arranged in the front-end equipment and generates a stationary phase reference electric signal, the stationary phase reference electric signal is modulated into a stationary phase reference optical signal, the stationary phase reference optical signal is transmitted to the rear-end equipment through a double-core optical fiber between the front-end equipment and the rear-end equipment, and returns the stationary phase reference optical signal into uplink and downlink phase shift information optical signals through an original path of the double-core optical fiber; and the uplink and downlink phase-shift information optical signals are demodulated into uplink and downlink phase-shift information electric signals, a phase difference generated by phase comparison between the uplink and downlink phase-shift information electric signals and a stationary phase reference electric signal are converted into uplink and downlink phase-shift control signals, and stationary phase control is performed on the uplink and downlink optical signals transmitted in the double-core optical fiber, thereby realizing stationary phase transmission of the bidirectional homologous coherent microwave optical fiber.

Description

technical field [0001] The invention relates to the technical field of microwave optical transmission, in particular to a bidirectional homologous coherent microwave optical fiber phase-stable transmission method. Background technique [0002] In the current microwave optical transmission system, after the signal is transmitted through the optical fiber, especially the long-distance optical fiber transmission, the propagation of the microwave optical signal in the optical fiber is affected by the external temperature. The phase of the microwave signal after the back-end photoelectric modulation changes greatly, especially when the optical fiber is affected. The external temperature changes, and its phase changes greatly, which cannot meet the long-distance phase stability requirements of microwave signals, thus restricting the application of microwave photonic technology in transmission systems such as radar. In order to avoid this problem of phase change caused by the influ...

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Problems solved by technology

[0002] In the current microwave optical transmission system, after the signal is transmitted through the optical fiber, especially the long-distance optical fiber transmission, the propagation of the microwave optical signal in the optical fiber is affected by the external temperature. The phase of the microwave signal after the back-end photoelectric modulation changes greatly, especially when the optical fiber is affected. The external temperature changes, and its phase changes greatly, which cannot meet the long-distance phase stability requirements of microwave signals, thus restricting the application of microwave photonic technology in radar and other transmission systems

In order to avoid this problem of phase change caused by the influence of external factors on the optical fiber, the current technology is improved from two aspects. The first is to use the method of phase-stabilized optical fiber, starting from the optical fiber itself, to increase the temperature drift coefficient of the optical fiber. However, this technology has poor effect on microwave phase stabilization. Compared with ordinary optical fiber, it can improve the phase change of microwave signal after optical fiber transmission, but it cannot make the phase absolutely stable, and it can only play a role in the phase change caused by external temperature changes. , for the influence of other factors such as vibration, the improvement effect is limited, and it cannot completely solve the phase change caused by the influence of external temperature on the optical fiber, and cannot satisfy the phase-stable transmission of microwave signals

The second is to use an electric phase shifter to quantitatively compensate the phase change of the optical fiber affected by the outside world. However, this phase shifting method cannot be quickly tracked because the phase shift degree of the optical fiber affected by the temperature is uncertain. Perform phase compensation, but can only compensate for a specific degree, cannot achieve multi-period continuous phase compensation, and at the same time cannot achieve tracking compensation for the phase change of the optical fiber affected by temperature

The third is that the currently used phase-stable feedback methods are all based on one-way transmission. If the transmission directions are different, different reference sources need to be placed in different positions. First, the uplink and downlink phase-stable transmission signals cannot be coherent. The size of the uplink and downlink optical transceivers is relatively large, and the design cost is also high. At the same time, the system is difficult to design and cannot be used in engineering applications.

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