Benchmarking five numerical simulation techniques for computing resonance wavelengths and quality factors in photonic crystal membrane line defect cavities

We present numerical studies of two photonic crystal membrane microcavities, a short line-defect cavity with relatively low quality ($Q$) factor and a longer cavity with high $Q$. We use five state-of-the-art numerical simulation techniques to compute the cavity $Q$ factor and the resonance wavelength $\lambda$ for the fundamental cavity mode in both structures. For each method, the relevant computational parameters are systematically varied to estimate the computational uncertainty. We show that some methods are more suitable than others for treating these challenging geometries.Comment: Revised and final version for publication. 28 pages, 10 figures, 7 table

Spectral Dependence of Deep Subwavelength Metallic Apertures in the Mid-wave Infrared

For two decades, extraordinary optical transmission (EOT) has amplified exploration into subwavelength systems. Researchers have previously suggested exploiting the spectrally selective electromagnetic field confinement of subwavelength cavities for multispectral detectors. Utilizing the finite-difference frequency domain (FDFD) method, we examine electromagnetic field confinement in both 2-dimensional and 3-dimensional scenarios from 2.5 to 6 microns (i.e., mid-wave infrared or MWIR). We explore the trade space of deep subwavelength cavities and its impact on resonant enhancement of the electromagnetic field. The studies provide fundamental understanding of the coupling mechanisms allowing for prediction of resonant spectral behavior based on cavity geometry and material properties. In addition to work on spectral response due to geometric parameters for subwavelength cavities, we investigate the spectral response with the inclusion of an absorber on the output in the mid-wave infrared. The placement of an absorbing layer causes a dramatic increase on the effective index within the subwavelength cavity while causing the cavity to become energetically leaky. We have found this broadens the spectral response of the cavity. To mitigate this undesired effect for spectral filter applications, we investigate modulation of the absorber-cavity field coupling by addition of an isolation layer; we show this layer decreases the spatial overlap of the cavity mode with the lossy absorber. In addition, we examine the effect of these layers on the quantum efficiency of the system. We also explore changing the material environment both within and surrounding the cavity to increase quality factors of designed cavities. We examine and quantify such systems by the trade-off that occurs between the quality factor and quantum efficiency. This trade-off occurs due to the spatial extent of fields in the propagating direction. The lateral spatial extent of the cavity is also examined by changing the lateral subwavelength spacing of a periodic array of cavities. The cavities are found to be sensitive to fields extending ~10x larger than the physical extent of the cavity. This phenomenon is indicative of the funneling effect. In addition, fabrication techniques were examined and found to be successful in creating the subwavelength features necessary for creation of such systems. The spectral response of fabricated devices was found to be in excellent agreement with simulation. This dissertation sets the groundwork for development of a novel multispectral detector in the MWIR by examining the spectral relationship of subwavelength cavities coupled to an absorber

Numerical methods for computing Casimir interactions

We review several different approaches for computing Casimir forces and related fluctuation-induced interactions between bodies of arbitrary shapes and materials. The relationships between this problem and well known computational techniques from classical electromagnetism are emphasized. We also review the basic principles of standard computational methods, categorizing them according to three criteria---choice of problem, basis, and solution technique---that can be used to classify proposals for the Casimir problem as well. In this way, mature classical methods can be exploited to model Casimir physics, with a few important modifications.Comment: 46 pages, 142 references, 5 figures. To appear in upcoming Lecture Notes in Physics book on Casimir Physic

3-D Metamaterials: Trends on Applied Designs, Computational Methods and Fabrication Techniques

This work was funded in part by the Predoctoral Grant FPU18/01965 and in part by the financial support of BBVA Foundation through a project belonging to the 2021 Leonardo Grants for Researchers and Cultural Creators, BBVA Foundation. The BBVA Foundation accepts no responsibility for the opinions, statements, and contents included in the project and/or the results thereof, which are entirely the responsibility of the authors.Metamaterials are artificially engineered devices that go beyond the properties of conventional materials in nature. Metamaterials allow for the creation of negative refractive indexes; light trapping with epsilon-near-zero compounds; bandgap selection; superconductivity phenomena; non-Hermitian responses; and more generally, manipulation of the propagation of electromagnetic and acoustic waves. In the past, low computational resources and the lack of proper manufacturing techniques have limited attention towards 1-D and 2-D metamaterials. However, the true potential of metamaterials is ultimately reached in 3-D configurations, when the degrees of freedom associated with the propagating direction are fully exploited in design. This is expected to lead to a new era in the field of metamaterials, from which future high-speed and low-latency communication networks can benefit. Here, a comprehensive overview of the past, present, and future trends related to 3-D metamaterial devices is presented, focusing on efficient computational methods, innovative designs, and functional manufacturing techniques.Predoctoral Grant FPU18/01965BBVA Foundatio