Linearization of radio-over-fiber systems using directly modulated and electro-absorption modulator integrated lasers

A low-cost linearization technique is proposed to improve RF signal power and suppress third order intermodulation distortion (IMD3) in radio-over-fiber (RoF) transmission systems. A directly modulated laser (DML) and an electro-absorption modulator integrated laser (EML) in C-band are both used for optical subcarrier modulation. The IMD3s induced by the two optical subcarrier modulations are suppressed by each other through adjusting the bias voltage of the electro-absorption modulator in the EML. In our initial experiments, the spurious free dynamic range (SFDR) is improved by more than 3.5 dB and output power at 1 dB compression point is improved by 4.3 dB.