Analyses of signal-to-noise ratio in optical-fiber heterodyne-type laser Doppler anemometer

In this work, we present a new mathematical model of signal formation in the optical-fiber heterodyne-type LDA. This model accounts for different noise sources in the LDA including those associated with the optical-fiber guides used in the LDA. This model allows one to access the signal-to-noise ratio (SNR) of the optical-fiber LDA as a function of the optical fiber parameters and characteristics of the laser source and photo-detector. We obtained the SNR under some typical combinations of LDA parameters. These included the laser power, photo-detector response, fiber attenuation, etc. Our analyses revealed the relative importance of different optical fiber parameters (optical absorption, Rayleigh and Brillouin scattering, etc) that together with the laser and photo-detector characteristics contribute to the SNR of the optical-fiber heterodyne-type LDA.