High power amplification of tunable optically carried RF signals by a diode pumped Yb³⁺ doped LMA silicon fiber

High power optically carried RF signal amplification is demonstrated. The output from a narrow-linewidth NPRO laser with central wavelength of 1064 nm is split into two parts. The frequency of one part is shifted by 150 MHz with an acoustooptic modulator and combined with the unshifted one. The combined beam has power of 50 mW and contains two frequency components with a frequency difference of 150 MHz. The power of the dual-frequency signal is amplified to 10 W using a diode laser pumped Yb³⁺-doped silica LMA fiber. The frequency separation as well as the relative power ratio remains the same before and after the amplifications. The tuning range of the beat frequency is from 125 to 165 MHz. The highest beat signal to noise ratio is 59 dB at a frequency of 150 MHz. The frequency and the power of the beat signal are stable after the amplification.