Tunable microwave photonic phase shifter based on slow and fast light effects in a tilted fiber Bragg grating.

A continuously tunable microwave phase shifter based on slow and fast light effects in a tilted fiber Bragg grating (TFBG) written in an erbium/ytterbium (Er/Yb) co-doped fiber is proposed and experimentally demonstrated. By optically pumping the TFBG, the magnitude and phase responses of the cladding mode resonances are changed, which is used to introduce a tunable phase shift to the optical carrier of a single-sideband modulated signal. The beating between the phase-shifted optical carrier and the sideband will generate a microwave signal with the phase shift from the optical carrier directly translated to the generated microwave signal. A tunable phase shifter with a tunable phase shift of 280° at a microwave frequency tunable from 24 to 36 GHz is experimentally demonstrated.