We proposed a novel structure that improved the linear characteristics of electroabsorption modulator (EAM) with composite quantum-wells as an absorption core layer. We fabricated three types of EAM's whose active cores were 8 nm thick, 12 nm thick and a composite core with 8 nm thick and 12 nm thick quantum-well (QW), respectively. The transfer functions of EAM's were investigated and their third-order inter-modulation distortion (IMD3) was obtained by calculation. The spurious free dynamic range (SFDR) was measured and compared with three types of QW. The linearity of the device with composite quantum-well showed a large enhancement in SFDR by 9.3 dBHz2/3 in TE mode and 7.0 dBHz2/3 in TM mode compared with the conventional EAM.

Using an electro-absorption duplexer (EAD) we presented a transceiver (TRx) module for dual function of both electrical-to-optical (E/O) and optical-to-electrical (E/O) conversion at 60 GHz band. The EAD chip was fabricated by monolithically integrating both a waveguide photodiode (PD) and an electro-absorption modulator (EAM) in association with traveling wave electrodes. We also investigated the issues of RF packaging in which the optoelectronic and electronic amplifier devices were co-packaged in a single housing. The RF impedance matching was accomplished in assistance with a microstrip bandpass filter.