METHOD OF MEASURING OPTICAL SIGNAL-TO-NOISE RATIO WITH FOUR-WAVE MIXING IN FIBER-OPTICAL TRANSMISSION SYSTEMS WITH FREQUENCY SEPARATION OF SIGNALS

摘要

FIELD: optics; communication equipment.SUBSTANCE: invention relates to an optical communication technique and can be used in fiber-optic transmission systems with frequency-separated channels. For this, a four-channel signal is proposed for the measurement. Frequency spacing between channels is uneven: 3Δf, 4Δf, 5Δf, where Δf is the frequency interval between the channels for the M-channel system. Amplification factor of the optical amplifiers is adjusted in such a way that the fiber maintains an optical power level corresponding to the transmission of the M-channel optical signal. Receiving side measures the power level in one of the four "active" channels and the noise power level in one of the "passive" channels, into which the combinational frequencies of the four-wave mixing fall. Optical signal-to-noise ratio for the four-channel signal is calculated using the obtained value, the ratio of the optical signal to noise for the transmission system with the M-channels is calculated.EFFECT: technical result consists in solving the technical problem of predicting the noise of four-wave mixing in a channel by means of transmission over an optical fiber.1 cl, 3 dwg