High-speed optical MSK modulation system and method

Abstract

The invention belongs to the technical field of optical fiber communication and optical network transmission and particularly relates to a system and method for modulating high-speed optical MSK (minimum shift keying) signals. The system mainly comprises four identical Mach-Zehnder modulators which are divided into an upper channel and a lower channel, used for biasing in different ways and further used for modulating according to the proper pre-coding scheme. The invention is capable of generating envelope-constant optical MSK signals under the condition of sine-wave drive, increasing the resistance of the generated optical MSK signals to the non-linear effect of optical fibers, reducing the sensitivity of a receiver in the optical fiber communication system and improving the transmission performance.

Description

technical field [0001] The invention belongs to the technical field of optical fiber communication and optical network transmission, and in particular relates to a high-speed optical minimum shift keying (MSK) signal modulation system and modulation method. Background technique [0002] Nowadays, the application of services such as high-speed Internet access, mobile phone voice data services, multimedia broadcasting systems, and large-capacity data networks for grid computing and remote storage is a great challenge to the bandwidth of communication systems. The optical communication system can support the capacity of Tb / s in the transmission distance of thousands of kilometers, making it the technical basis of the large-capacity transmission system. [0003] Optical fiber communication has become the preferred choice for backbone transmission due to its huge bandwidth resources and good communication quality, and the application of wavelength division multiplexing (WDM) tech...

AI Technical Summary

Problems solved by technology

In practical applications, if the modulation speed is increased to more than 40Gb / s, the rate of the required triangular wave driving signal is higher. However, it is difficult to generate a high-speed ideal triangular wave signal, and it is difficult to extract the clock signal, which makes it difficult to demodulate the generated MSK signal.

When the triangular wave signal is divided into two channels to drive MZM, one of them needs to be delayed by one bit. If the delay control is not accurate enough, it will have a great impact on the generated optical MSK signal.

[0012] Although the phase of the optical MSK signal generated by using a sine wave at the same rate instead of a triangular wave is continuous, the phase change within a bit is But the envelope of the optical MSK signal is not constant, it is constantly changing

This inevitably leads to weakening of its resistance to nonlinear effects. At the same time, the inconsistency of the envelope causes a protrusion in the middle part of the eye diagram of the demodulated signal generated when demodulating with delay interference, which reduces the eye opening ( EOP)

Similar to the prior art 1, when the sinusoidal signal is divided into two channels to drive the MZM, one of them needs to be delayed by one bit. If the delay control is not accurate enough, it will have a great impact on the generated optical MSK signal

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