Articles
Optics and Laser Technology (00303992)181
Given the pivotal role and extensive applications of optical data routing and processing units in optical information technology, we propose a novel mechanism for switching the optical behavior of plasmonic nanoresonators within photonic integrated circuits. The key concept here is to utilize the Pockels effect not to induce a uniform change in the refractive index profile, but rather to establish an exponential refractive index profile across the nanodisk. This behavior resembles what happens in a mirage phenomenon: the light wave is unable to complete its full path around the nanodisk and is instead reflected back. The proposed plasmonic design bypasses low-transmitted signals and converts them into sharp-band reflected signals in response to a designed bias voltage. Moreover, to the best of our knowledge, our design is the first to achieve the EIT phenomenon and slow light effect using a single resonator, a significant simplification over conventional methods that typically necessitate the use of multiple resonators. This is achieved by creating interference between upward and mirage-induced downward waves, resulting in a transparency window and significant dispersion. © 2024 Elsevier Ltd
Applied Optics (21553165)63(21)pp. 5738-5745
In our study, we investigate the resonance modes of plasmonic nanodisks through numerical simulations and theoretical analysis. These tiny structures exhibit fascinating behavior, but relying solely on mode localization is not sufficient to classify their supported modes as plasmonic or dielectric. Our goal is to address this challenge by introducing a robust method for identifying each mode’s true nature. Moreover, through analysis of the field distribution, we introduce, to our knowledge, a novel metric designed for application in inverse problems within the realm of machine learning. This metric serves as a robust tool for optimizing the performance of photonic devices. © 2024 Optica Publishing Group.
Applied Optics (21553165)63(30)pp. 8007-8015
The management of orbital angular momentum (OAM) in frequency conversion processes is essential for numerous applications such as quantum and classical optical communications. This paper presents a wavefront modulation approach for the fundamental beam in second harmonic generation (SHG) to efficiently control the OAM spectrum. We employ an inverse design method to derive the necessary wavefront shape of the fundamental beam for achieving a desired SHG OAM spectrum. Specifically, we introduce an efficient inverse design technique based on physics-guided neural networks (PGNNs) that incorporates the coupled equations governing SHG, aimed at tailoring the OAM spectrum of SHG. Utilizing the proposed PGNN, we design the phase pattern for a spatial light modulator (SLM) to shape the wavefront of the fundamental beam. Furthermore, we present a novel loss function, to our knowledge, that effectively links the OAM of the SHG spectrum and efficiency to the SLM phase pattern and crystal temperature, independent of empirical weight coefficients. The proposed PGNN facilitates the purification of the SHG OAM spectrum, even when the fundamental beam comprises mixed Laguerre–Gaussian (LG) modes. Additionally, we demonstrate the generation of desired SHG spectra using the proposed PGNN framework. This study introduces what we believe to be a groundbreaking inverse design method for developing photonic devices with customized functionalities, addressing challenges associated with traditional data-driven deep learning techniques. © 2024 Optica Publishing Group.
Journal of Optics (United Kingdom) (20408986)26(8)
In recent years, extracting information from superposed vortex beams has been a topic of intense study. In this paper, complex coefficients of various superpositions are measured in both simulation and experiment by proposing and implementing four different sampling methods. Superposed vortex beams are experimentally generated using a digital micromirror device, and recorded on a 2 f optical imaging setup. To extract both amplitude and phase values of modal coefficients, a single intensity frame of the beam is sampled in the form of concentric circles, sectors, random circles, and random squares. Considering just specified parts of the intensity instead of the whole to sample the pattern increases the speed of the modal coefficient extraction. Besides, a linear set of coherent equations is solved, and achievements are compared together. As a consequence, measuring both the amplitude and phase values of coefficients simultaneously can pave the way to enable high-capacity optical communication which is carried out in this research with better than 99% and 96% accuracy, respectively. © 2024 IOP Publishing Ltd.
