Method of high-precision automatic balance of coherent detection system

Abstract

The invention provides a method of high-precision automatic balance of a coherent detection system. In a coherent detection system, signal light and local oscillation light output two paths after mixing and a detector detects light signals to acquire electric signals and then differential mode signals are obtained through subtracting; because of the time delay difference and the light power difference of the two light paths generated after mixing, the common mode rejection ratio is reduced. According to the invention, a balancing light path module is added to delay and attenuate light signals,the time delay difference of two light paths is fixed, and the time delay can be controlled by accurately controlling the length of the two light paths; the light power of the two light paths have certain difference and the light power of the two light paths is adjusted in such a manner that a data processing module performs real-time data processing on differential mode signals and feeds corresponding information back to the balancing light path module, so that the objective of high-precision balance can be achieved. The method can effectively realize high-precision balance of two light paths of a coherent detection system, guarantee long-time stable work of the system and increase the common mode rejection ratio of the system.

Description

technical field [0001] The invention relates to the field of photoelectric detection, in particular to coherent detection, which realizes the high-precision balancing technology of two optical paths of a coherent detection system, in particular to a high-precision balancing method of a coherent detection system. Background technique [0002] At present, photoelectric detection technology is divided into direct detection technology and coherent detection technology. The optoelectronic system of the direct detection technique responds directly to the intensity of the optical radiation without involving the coherent nature of the optical radiation. Coherent detection responds to the coherent field of optical radiation and can detect information such as the amplitude, frequency, and phase of the optical wave. The common-mode rejection ratio is a very important technical indicator in the coherent detection system. It refers to the ratio of the voltage amplification factor of the...

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Problems solved by technology

Ideally, the common-mode signal of the coherent detection system should be 0, but the actual device cannot be completely symmetrical, so it will generate a common-mode signal and reduce the system sensitivity

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