Full L-band 40-Gbit/s operation of compact InP-DQPSK modulator module with low constant driving voltage of 3.5 Vpp

Operation at 40 Gbit/s with a constant driving voltage (3.5 Vpp) for the entire L-band was demonstrated with a newly developed compact InP-based DQPSK module. A linear DC bias voltage control was employed to compensate for a wavelength dependence of the half-wavelength voltage.