Optical transmitter module with hybrid integration of DFB laser diode and proton-exchanged LiNbO3 modulator chip

In this work, a hybrid integrated optical transmitter module was designed and fabricated. A proton-exchanged Mach-Zehnder lithium niobate (LiNbO3) modulator chip was chosen to enhance the output extinction ratio. A fiber was used to adjust the rotation of the polarization direction caused by the optical isolator. The whole optical path structure, including the laser chip, lens, fiber, and modulator chip, was simulated to achieve high optical output efficiency. After a series of process improvements, a module with an output extinction ratio of 34 dB and a bandwidth of 20.5 GHz (from 2 GHz) was obtained. The optical output efficiency of the whole module reached approximately 21%. The link performance of the module was also measured.