Laser Frequency Noise Measurement by Forming an Interference Signal with Subcarrier Frequency

The paper presents a method for measuring laser frequency noise spectrum with the use of unbalanced fiber-optic interferometer and auxiliary phase modulation, forming a subcarrier signal at the interferometer output. The main features of the proposed method are analyzed. The paper also presents the results of experimental validation of the proposed method by measuring laser frequency noise of a high-coherent optical fiber laser.