Integrated Photonics for Intense Light-matter Interaction and Applications in Aerospace

Abstract

Integrated photonics is poised to disrupt the way information is parsed and transmitted, as a seamless pairing of optical and opto-electronic elements alongside electrical integrated circuits on semiconductor chips provides light-speed signaling, compactness, and low power consumption – all while maintaining compatibility with mature silicon CMOS manufacturing techniques. In this dissertation, I (1) develop component-level design techniques for realizing high-performance integrated photonics and (2) advance novel photonics applications for state-of-the-art photonic integrated circuits, namely for aerospace missions. (1) Novel design strategies are developed to realize subwavelength engineered photonic crystals (PhCs) with (a) anti-slot and (b) slotted unit cell designs using deep ultraviolet lithography in a monolithic silicon photonics foundry. The anti-slot and slot have minimum features near 70 (silicon width) and 50 (void gap) nm, respectively, which are the smallest features achieved in a commercial photonics platform to date. These PhC structures achieve up to fourfold enhancement in on-chip optical energy confinement compared to wavelength scale designs and may be used (a) in communications to reduce the VπL figure of merit in Mach-Zehnder modulators by up to a factor of five compared to traditional waveguide designs or (b) in sensing and quantum information platforms to enhance the sensitivity of light-matter interaction with an analyte or emitter. (2) Radiation reliability physics and performance susceptibilities are examined for integrated photonic devices, including (a’) Ge-Si photodiodes and (b’) anti-slot PhCs operating in harsh conditions – particularly the radiation-rich environment in space. (a’) I report robustness of optical characteristics (e.g. quantum efficiency, photodiode bandwidth) to total ionizing dose and displacement damage, with only modest increases in dark currents (on the order of 3–4 dB) and photodiode ideality factor. These changes are critical to characterize for implementation in photonic integrated circuits (PICs) with strict attenuation budget requirements, but do not preclude use for space missions. (b’) Despite the intense light-matter interaction engineered into anti-slot PhCs with subwavelength features, no sensitivity is observed in spectral features under proton irradiation, suggesting that systems employing advanced geometrical designs are tolerant to radiation in space. Finally, I develop PIC packaging and characterization techniques, which are broadly applicable for evaluating integrated photonics devices and systems in a repeatable, robust fashion while also enabling experiment portability beyond specialized laser labs and into a wide range of test environments.