High power tunable beat frequency signal by all fiber dual-frequency amplification

The output power of dual-frequency laser source is usually low that it cannot meet the requirements of measurement of long distance. The amplification of 125-165 MHz sweep beat frequency signal using an all-fiber master oscillator power-amplifier (MOPA) system is demonstrated. A non-planar ring oscillator laser (NPRO) with central wavelength of 1064 nm is designed as the single frequency laser seed. An acoustic modulator with central frequency of 150 MHz is used to produce 50 mW dual frequency signal with combination of master and diffraction beam by 1064 nm frequency shifting. The power of dual frequency laser is boosted up to 10 W. The beat signal can sweep from 125 MHz to 165 MHz. The relative magnitude of the two single-frequency signals is maintained in the amplification process and the maximal output power of beat signal can be realized by polarization controlling. The signal noise rate and bandwidth of beat signal are also experimented and analyzed.