First experimental demonstration of phase locking of amplified optical fiber arrays by RF phase modulation

The first demonstration of phase locking of 2 and 5 element fiber amplifier arrays using RF phase modulation is presented. Each leg of the fiber amplifier array is modulated with a separate RF frequency, thus tagging the phase shift for each leg by a separate RF frequency. The reference beam is spatially overlapped with all the RF modulated beams fiber leg beams onto a single detector. The phase shift between the optical wave in the reference leg and in the RF modulated legs are measured separately in the electronic domain and the phase error signal is feedback to the LiNbO₃ phase modulator for that leg to minimize the phase error for that leg relative to the reference leg.