Low-noise optical amplifier

The utility model relates to the field of optical communication, and discloses a low-noise optical amplifier, which comprises an optical fiber amplifier and an optical filter, wherein the optical filter is a turnable optical filter of which filtering frequency can be turned, and the filtering pass band of the optical filter is identical to that of an optical signal channel to be amplified. By additionally arranging the turnable optical filter (TOF) with turnable wavelength and bandwidth on input stage, intermediate stage or output state of the optical fiber amplifier, the low-noise optical amplifier is obtained, which effectively filters the ASE noise while amplifying the signal optical power, improves the system optical signal to noise ratio and amplifier pump conversion efficiency, and is beneficial to amplification and transmission of small signals and improvement of detection sensitivity; and the multiplexing turnable optical filter can ensure the consistency of tuning wavelength accurately, is simple to