Synthetic-single-sideband-signal-based linear direct detection method and system for optical signals

Abstract

The invention discloses a synthetic-single-sideband-signal-based linear direct detection method and system for optical signals. The system is composed of a local oscillator laser, a coupler, a photodetector, a radio frequency amplifier, an electrical filter, an analog-to-digital converter (ADC), and a digital signal processor (DSP). The local oscillator laser is arranged at the edge of one side ofan incident optical signal spectrum; wave synthesis with an incident light signal is carried out by the coupler to form a single sideband signal that is inputted into the photodetector. An analog signal outputted by the photodetector is amplified and filtered; the ADC converts the processed signal into a digital signal; the DSP uses the input digital signal as the real part and Hilbert transformas ant imaginary part to carry out adding to obtain a complex signal representing the synthesized single sideband optical signal light field; and then an incident light signal light field is recoveredbased on a frequency offset compensation algorithm. According to the invention, digital coherent detection of the incident light signal light field is realized by using one photodetector and one ADC.The system has advantages of simple structure, low cost and low power consumption.

Description

technical field [0001] The invention belongs to the fields of optical fiber communication, free space optical communication, optical signal detection and digital signal processing, and more specifically relates to a linear direct detection method and system based on synthetic single sideband signals. Background technique [0002] At present, optical communication systems mainly use intensity modulation and direct detection technology. The optical receiver based on the direct detection technology uses a single photodiode to convert the optical signal into an electrical signal. The intensity information of the signal light is detected. Since the intensity modulation does not make full use of all the modulatable dimensions of the light field, the transmission efficiency is low, and it is difficult to meet the growing needs of high-speed and large-capacity communication systems. Coherent detection can detect the intensity, frequency, phase and polarization of signal light in v...

AI Technical Summary

Problems solved by technology

However, the current linearization technology based on the minimum phase signal still has some shortcomings. For example, there is a spectrum broadening effect in the logarithmic operation of the DSP when reconstructing the light field information, which makes the ADC insufficient to restore the full field information at the conventional 2 times the sampling rate. (At least 3 times the sampling rate is required), if the iterative algorithm is introduced to reduce the sampling rate to 2 times the conventional one, it will bring an additional huge amount of calculation, which puts forward extremely high requirements for the speed of DSP data processing

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