A Measurement Technology of Phase Frequency Noise Characteristic of Weak Laser Signal

Abstract

The invention discloses a phase-frequency noise characteristic measurement technique for a weak laser signal, the phase-frequency noise characteristic measurement technique for the weak laser signal comprises a to-be-measured weak laser light source, an erbium-doped fiber amplifier, a coupler, a 120-degree phase difference interferometer and an industrial personal computer; the to-be-measured weaklaser light source amplifies a weak signal of the light source through the erbium-doped fiber amplifier, the amplified signal of the light source is split into two light sources by the coupler, the first light source is used for testing the phase-frequency noise characteristic of the to-be-measured weak laser light source, the second light source is used for feeding back the amplified signal of the light source to a power detection unit, and the laser power incident on the 120-degree phase difference interferometer is kept on the same level; and the first light source is incident on the 120-degree phase difference interferometer, the 120-degree phase difference interferometer is used for demodulating differential phase information of the signal of the first light source, and the differential phase information is transmitted to the industrial personal computer to be analyzed. The phase-frequency noise characteristic of the weak signal is tested, and the phase-frequency noise characteristic measurement technique is favorable for studying the influence of the weak signal on the whole system performance.

Description

technical field [0001] The invention belongs to the technical field of lasers, and in particular relates to a technique for measuring phase-frequency noise characteristics of weak laser signals. Background technique [0002] When the laser is transmitted along a long-distance optical fiber link, in order to avoid the influence of the stimulated Brillouin effect, it is usually necessary to ensure that the transmitted light is below the stimulated Brillouin threshold, so the signal light at the receiving end is generally weak. In order to better study the characteristics of the signal light and deeply study the influence of the signal light on the subsequent system, we need to accurately characterize and measure its phase-frequency noise characteristics. [0003] In 2013, Yang Fei et al. from the Shanghai Institute of Optics and Mechanics proposed a single-frequency laser phase-frequency noise test technology based on a 120-degree phase-difference interferometer (existing tech...

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Problems solved by technology

However, limited by the loss of the entire interference system and the signal-to-noise ratio of the system, this method requires an incident power of about 10 dBm, so the weak laser signal cannot be directly measured by the proposed system

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