Study of advanced resonant photonic gratings in the mid-infrared spectrum for the chemical sensing applications
Abstract
This dissertation focuses on developing advanced Mid-IR optical devices for chip-scale chemical sensing. Various Mid-IR techniques based on Beer-Lambert’s law offer valuable insights into molecular interactions but suffer from bulkiness and
high cost. Towards the compact and cost-effective sensing purpose, many efforts have been made in light sources (e.g., QCLs), photodetectors (e.g., PbSe, MCT detectors), and gas sampling chambers via on-chip photonic waveguides. Despite
the progress achieved through these new technologies, there is still plenty of room for enhancing the performance and cost-effectiveness of miniaturized Mid-IR gas sensing systems.
Thus, this dissertation explores new photonic engineering pathways to address existing challenges through on-chip integration and downsizing in three core mid-IR gas sensing components, including the light source, detector, and interaction path. In this dissertation, a simple yet versatile and powerful resonant grating platform has been utilized as the foundation to develop innovative engineering methods. Herein, due to the nontrivial properties of High Contrast Gratings
(HCGs), such as broadband reflectivity, and high Q factor resonance, I focus mostly on these types of grating resonators.
Through a new design, HCGs are used to enhance absorption in uncooled PbSe-based photodetectors. Moreover, for shrinking the interaction path, a high
Q factor HCG resonator was designed, showing 600 times light absorption
enhancement in a micro-size path length. Furthermore, integrating active HCGs
with Parity-Time (PT) symmetry concept offers near-zero bandwidth photonic
resonant emission with application in Mid-IR light sources. Besides the
exploration of new photonic design methods, another important aspect of this
work has been focused on the development of a suitable mid-IR material platform to allow the implementation of the aforementioned photonic design methods.
Specifically, a modified chemical deposition method is used to synthesize
Oriented-Attached (OA) PbSe nanocrystals (NCs) on amorphous substrates
with strong quantum confinement and broad size-tunability. This optimized and
cost-effective growth technique demonstrates promising illumination in the
Mid-IR range, contributing to the potential of OA PbSe NCs synthesized by this
novel method as a material for fabricating Mid-IR photonic components. At the
end of this dissertation, an experimental exploration of a low-cost and large-area
patterning nanofabrication method is also presented as an extended effort from
the core photonic design and novel material synthesis works towards the
overarching goal to develop smaller, cost-effective, and efficient on-chip mid-IR
optical devices for chemical sensing applications.
Collections
- OU - Dissertations [9390]
The following license files are associated with this item: