Mid-infrared metasurfaces for third-harmonic generation

Abstract

This dissertation delves into the field of mid-infrared (MIR) photonics, focusing on the development of nonlinear polaritonic metasurfaces for third-harmonic generation (THG). The mid-infrared range, spanning 3 to 15 micrometers, is crucial for a variety of applications, including chemical sensing, environmental monitoring, and medical diagnostics. The core of this research lies in exploiting the unique optical properties in the MIR region through advanced photonic devices. Recent advancements in metasurface technology, which utilize two- dimensional structures at subwavelength scales, have revolutionized the manipulation of light in ways previously unattainable with traditional optical components. These metasurfaces enable unprecedented control over light's polarization, phase, and amplitude, leading to applications in flat optics, beam forming, and optical holography. An advanced study of the metasurface explores active and nonlinear metasurfaces, particularly those capable of efficient frequency conversion and dynamic beam control. The dissertation introduces nonlinear polaritonic metasurfaces, combining multi-quantum-well (MQW) structures with plasmonic nanoresonators, to achieve enhanced nonlinear responses in the MIR region. These metasurfaces exhibit significantly higher nonlinear susceptibilities compared to conventional materials, opening new possibilities for frequency conversion and optical modulation. Two main platforms are presented: passive and active nonlinear polaritonic metasurfaces. The passive platform incorporates engineered MQW structures for enhanced third-order nonlinear susceptibility, effectively converting this response to an in-plane effective element of the metasurface. The active platform explores electrically tunable and mechanically stretchable metasurfaces, employing the Quantum-Confined Stark Effect and integration with PDMS layers. These platforms enable efficient THG generation, dynamic intensity modulation, and beam manipulation. Additionally, the dissertation briefly introduces the development of a standoff chemical detector using a quantum cascade laser. This system integrates optical modules and detection algorithms for analyzing liquid chemical absorption spectra, demonstrating the practical applications of mid-infrared chemical detection and identification. Overall, these studies contribute significantly to the field of mid-infrared photonics, particularly in the development and application of nonlinear polaritonic metasurfaces, paving the way for advanced photonic devices with wide-ranging applications.