| The development of 3D photonic integrated circuits (PICs) is critical for the optoelectronic IC industry to match the advances of the electronic IC industry. Traditional 2D PICs are limited by substrate size and the number of electrical and optical connections that can be made to the chip. This is a problem for the increasingly dense, complicated circuits developed today. By making the leap to multi-layer interconnects, more compact devices and further creativity in circuit design can be obtained. Also, because different types of devices (lasers, detectors, switches, etc.) are often best made with different materials, methods of integrating different materials onto a single chip must be addressed. 3D routing of signals will be very advantageous for significantly more compact and powerful PICs.; Through wafer bonding, vertically coupled semiconductor waveguide devices provide a means to obtain many of the above desired characteristics. Various novel filtering, add-drop multiplexing, and beam splitting devices of InP/InGaAsP for signals around 1550 nm have been realized.; A three-layer double-bonded waveguide vertical coupler 1:8 beam splitter is demonstrated. The strongly coupled waveguides allow a 580-micron device length, more than one hundred times shorter than that of the equivalent horizontal coupler. A vertically coupled crossed-waveguide four-channel optical add-drop multiplexer (OADM) has been realized. It is one of the first optical vertically coupled devices with no horizontally coupled counterpart. OADMs of truncated gaussian layout have been fabricated based an investigation of optimal OADM waveguide layout shapes to reduce sidelobe levels and filter bandwidths. These devices illustrate the use of multiple vertical layer optical interconnects for 3D routing of optical signals. The design, processing, and measurement results of these devices are also presented in this dissertation. Wafer bonding is a powerful tool that may provide the future for complex multi-level, multiple material, densely integrated PICs. |
