A Silicon Platform With MEMS Active Alignment Function and Its Potential Application in Si-Photonics Packaging

A silicon (Si) platform, which consists of passive alignment structures (V-grooves), active microelectromechanical systems (MEMS) alignment components, mechanical locking mechanisms, and predeposited gold–tin soldering pads is developed to address the submicron accuracy assembly requirement of the discrete laser diode (LD) to a small core in-chip Si waveguide (WG). A 2-D in situ active alignment of a ball lens in LD-ball lens–Si-WG coupling system is presented here. The 1550-nm DFB LD and the passive Si-photonics chip are attached onto the platform, using flip–chip bonding process. The 2-D alignment of the ball lens is then achieved through the in-plane motion of the suspension arms and the specially designed V-groove. The position of the ball lens is subsequently fixed by the locking mechanism mechanically. MEMS electrothermal V-beam actuators, which can provide large force with a large displacement under a low driving voltage, i.e., >50 $\mu$m at 25 V are employed in this platform. The effectiveness and stability of the arm locking function have been tested with a shift of <0.1 $\mu$m after vibration testing (10g , 2 kHz). The integrated aligning and locking functions of the MEMS platform are also demonstrated through the LD-ball lens–Si-WG coupling system. These results show the potential of this MEMS platform in hybrid integrated Si photonics and applications that consist of LD-ball lens–Si-WG coupling system, e.g., the transmitter and transceiver.