Silicon, silica, and germanium photonic integration for electronic and photonic convergence

Abstract

Silicon (Si) photonic wire waveguides provide a compact photonic platform on which passive, dynamic, and active photonic devices can be integrated. This paper describe the demonstrations of several kinds of integrated photonic circuits. The platform consists of Si wire, silicon-rich Si dioxide (SiO x ) and Si oxinitride (SiON) waveguides for passive devices and a Si rib waveguide with a p-i-n structure and a germanium (Ge) device formed on Si slab for active devices. One of the key technologies for the photonic integration platform is low temperature fabrication because a back-end process with high temperature may damage active and electronic devices. To overcome this problem, we have developed electron cyclotron resonance chemical vapor deposition as a low-temperature deposition technique. Another key technology is polarization manipulation for reducing polarization dependence. A polarization diversity circuit is fabricated by applying Si wire and SiON integration. The polarization-dependent loss of the diversity circuit is less than 1 dB. Moreover we have developed several kinds of integrated circuit including passive, dynamic and active devices. Ge photodiodes are monolithically integrated with an SiO x -arrayed waveguide grating (AWG). We have confirmed that the operation speed of the integrated Ge photodiode is over 22 Gbps for all 16 channels. Variable optical attenuators (VOAs) fabricated on the Si p-i-n rib waveguides and an AWG based on the SiO x waveguide are integrated successfully. The total size of 16-ch-AWG-VOAs is 15 8 mm 2 . The device has already been made polarization independent. Furthermore electronic circuits are successfully mounted on the integrated photonic device by using flip-chip bonding.