Narrow band electroabsorption modulator modules for a 60-GHz radio-over-fiber link

We developed a narrow band electroabsorption modulator (EAM) module for RF/optic conversion at 60 GHz. From the laser trimmed RF feeding submount, we obtained a transmission bandwidth at S-11 = -10 dB that was as large as 2.2 GHz, and we found a resonance peak at 60 GHz. The EAM module showed an enhanced E/O response around 60 GHz. Sixteen quadrature-amplitude-modulation data were transmitted with a signal-to-noise ratio (SNR) of 27.9 dB in a back-to-back case and 25.8 dB through a 20-km fiber spool. The linearity of a 60-GHz radio-over-fiber (RoF) link including the EAM module was investigated. The lowest 3rd order intermodulation distortion was -53.17 dBc at -1.6 V with an RF input power of -16 dBm. The spurious free-dynamic range of the 60 GHz RoF link had a maximum value of 112.10 edB.Hz(2/3) at -1.6 V. With an optical input 4 dBm, the 60 GHz RoF link with EAM modules had the highest link gain and the best linearity at a bias voltage of -1.6 V.