Dual-frequency distributed feedback fibre laser for microwave signals generation

Presented is a new dual-frequency laser based on an erbium-doped distributed feedback fibre laser operating on two orthogonally polarised eigenstates around 1.55 µm, exhibiting a frequency offset in the microwave domain. The beatnote in the free running regime between these two optical waves allows the generation of an RF signal around 1 GHz with a RIN lower than −115 dB/Hz over the frequency range 50 kHz to 10 MHz and a phase noise of −67 dBc/Hz at 10 kHz of the RF carrier. Up to 600 MHz tunability of the beatnote is obtained by mechanical stress applied to the cavity.