Integrated Optical Add-drop Multiplexer And Slot Waveguide On Silicon Substrate

Integrated photonic device on silicon substrate has attracted great attention since it could be manufactured by CMOS standard process with large volume. One of the applications is on-chip optical interconnect for future high performance processor. Compared with electrical interconnect, optical transmission link could be more superior in the terms of high data transmission rate, high bandwidth, low power consumption, electromagnetic immunity, no impedance matching required and so on. In an on-chip high speed wavelength division multiplexing(WDM) transmission link, integrated optical add-drop multiplexer(OADM) is one of the key component for the routing of WDM channel. This dissertation has focused on increasing the operating channels and switching speed.Another research highlight of integrated photonic device on silicon substrate is lab on a chip(LOC) system. Such system integrate the functions of bio-imaging, labelling, sensing, medical localization and expression on a single chip so that it could reduce the time to synthetic and analyze products, well control the molecular concentrations and interactions, and reduce the reagent costs as well as chemical waste. The operating wavelength of LOC system is usually at visible band. One possible solution is adopting gallium nitride(GaN) fabricated on silicon substrate to realize both light source and waveguide. Such scheme not only takes advantage of the high luminous efficiency of GaN light source, but also reduces the footprint and makes the alignment of waveguides more accurate. In order to overcome the material absorption of GaN in visible band, we have calculated and optimized GaN slot waveguide with low transmission loss, which is similar to our previous proposal to realize all-silicon photonic integrated circuit with slot waveguide.The main achievements of this dissertation are summarized as follows:1. An 8-channel thermally tuned OADM is entrusted to be fabricated by a foundry with CMOS compatible process, and is characterized by a modified testing platform. The tested results show that, the average passband bandwidth is 0.36 nm, the average dropping loss is 2.6 dB, the adding loss is 2.2 dB, the average shape factor is 0.3, and the channel crosstalk is less than-20 dB.2. A 4-channel electrically tuned OADM is fabricated and characterized. Dropping function is realized with 8 dB additional loss, the 3-d B bandwidth is 0.1 nm, the electrically tuning efficiency is 0.22 nm/mA. The impact of carrier injection is analyzed and possible solutions are discussed.3. Simulations and optimizations have been done towards GaN slot waveguide operating within visible band. When only considering material absorption, the transmission loss of optimized GaN slot waveguide is 0.4-1.0 dB/cm. After taking sidewall roughness into account, the total transmission loss is 1-2.5 dB/cm while the standard deviation of interface roughness is 1 nm. These results indicate that GaN slot waveguide is a promising candidate as a visible light transmission line in LOC system.