Linearization of an intensity-modulated analog photonic link using an FBG and a dispersive fiber

An optical linearization technique for an intensity-modulated analog photonic link is proposed and demonstrated. Conventional double-sideband intensity modulation is applied to modulate the radio frequency (RF) signal onto the optical carrier; then a fiber Bragg grating (FBG) is used to suppress part of the optical carrier and a single mode fiber (SMF) is followed to introduce some dispersion. By properly adjusting the dispersion-induced phase shift, the third-order intermodulation distortion can be suppressed. The proposed scheme is simple and low cost. The FBG can be also used to optimize the power ratio of the optical carrier and sidebands, thus improving the link gain, while the SMF can act as a transmission medium to deliver the RF signal. Experimental results show that an improvement of 12.6 dB in the spurious-free dynamic range and 3.8 dB in the link gain is achieved after linearization. The frequency tunability of the linearization technique is also evaluated by the transmission of RF signals with different center frequencies and bandwidths.