Integrated photonic devices for electromagnetic wave sensing, optical true time delay, and trace gas sensing

Investigations on how informative signals interact with optical light wave propagating in integrated photonic devices have been emerging research topics for various sensing and high-speed communication applications. These have become attractive research fields since integrated photonic devices offer unparalleled advantages such as high sensitivity, high-density integration, low power consumption, and great electromagnetic interference immunity. Among all available material platforms for integrated photonic devices, silicon is one of the ideal materials since silicon has excellent optical waveguides properties such as high transparency and high refractive index in optical communication wavelengths. These properties enable low loss and compact on-chip silicon photonic devices. Also, silicon photonic devices benefit from mature silicon-based semiconductor nanofabrication facilities; therefore, they can be fabricated with low cost. On the other hand, silicon photonic devices built on typical silicon dioxide-based silicon-on-insulator wafers can’t be operated beyond the wavelength of 3.5 μm due to high intrinsic mid-infrared absorption of silicon dioxide. Indium phosphide becomes an alternative candidate due to low optical loss. In addition, indium phosphide-based quantum cascade lasers provide narrowband tunable continuous-wave room-temperature emission in the entire mid-infrared spectral range from 3-11 μm which makes monolithically integrated devices possible. Wide varieties of photonics devices on both silicon and indium phosphide platforms have been demonstrated so far such as high-speed modulators, low loss waveguides, couplers, optical phased arrays, and sensors. In this dissertation, silicon integrated photonic devices for electromagnetic wave sensing and optical true time delay lines, as well as indium phosphide-based integrated photonic devices for trace gas sensing, are presented. This dissertation shows that integrated photonic devices are promising for high-performance sensing and novel communication applications.