1.27 kW, 2.2 GHz pseudo-random binary sequence phase modulated fiber amplifier with Brillouin gain-spectrum overlap.

We present a 2.2 GHz modulated, 1.27 kW output power, monolithic fiber amplifier based on pseudo-random binary sequence (PRBS) phase modulation. The spectral line spacing of maximizing the threshold enhancement factor (plateau of trend) was found by theoretical simulation. The spectral line spacing was adjusted to 12.7 MHz by a pattern length of n = 9, which is close to the plateau of trend in the proposed architecture. A 2.2 GHz low-pass radio frequency filter was used to control the FWHM of the seed. A four-stage Yb-doped fiber amplifier chain was established to boost a distributed Bragg reflector (DBR) laser and a distributed feedback (DFB) diode laser to 1.2 kW and 1.27 kW with a backward reflectively of <1‰, which shows a good suppression of SBS effect.