Ideal phase-locked-loop (PLL) operation of a 10GHz erbium-doped fibre laser using regenerative modelocking as an optical voltage controlled oscillator

Ideal phase-locked-loop (PLL) operation of a 10GHz erbium-doped fibre laser has been achieved for the first time by using a voltage controlled regenerative modelocking technique. The repetition rate of the regeneratively modelocked fibre laser in a free running condition can be continuously varied by changing the voltage supplied to the PZT to change the fibre cavity length. PLL operation is achieved by feeding back a phase sensitive error signal to the PZT. This signal is obtained by mixing a laser clock signal with a synthesiser signal. The external signal tracking range is 40kHz.