Two-dimensional (2D) materials have revolutionized the field of optoelectronics by offering exceptional properties such as atomically thin structures, high carrier mobility, tunable bandgaps, and strong light–matter interactions. These attributes make them ideal candidates for next-generation photodetectors operating across a broad spectral range—from ultraviolet to mid-infrared. This review comprehensively examines the recent progress in 2D material-based photodetectors, highlighting key material classes including graphene, transition metal dichalcogenides (TMDCs), black phosphorus (BP), MXenes, chalcogenides, and carbides. We explore their photodetection mechanisms—such as photovoltaic, photoconductive, photothermoelectric, bolometric, and plasmon-enhanced effects—and discuss their impact on critical performance metrics like responsivity, detectivity, and response time. Emphasis is placed on material integration strategies, heterostructure engineering, and plasmonic enhancements that have enabled improved sensitivity and spectral tunability. The review also addresses the remaining challenges related to environmental stability, scalability, and device architecture. Finally, we outline future directions for the development of high-performance, broadband, and flexible 2D photodetectors for diverse applications in sensing, imaging, and communication technologies.

Gas sensing is essential for detecting and measuring gas concentrations across various environments, with applications in environmental monitoring, industrial safety, and healthcare. The integration of two-dimensional (2D) materials, organic materials, and metal oxides has significantly advanced gas sensor technology, enhancing its sensitivity, selectivity, and response times at room temperature. This review examines the progress in optically activated gas sensors, with emphasis on 2D materials, metal oxides, and organic materials, due to limited studies on their use in optically activated gas sensors, in contrast to other traditional gas-sensing technologies. We detail the unique properties of these materials and their impact on improving the figures of merit (FoMs) of gas sensors. Transition metal dichalcogenides (TMDCs), with their high surface-to-volume ratio and tunable band gap, show exceptional performance in gas detection, especially when activated by UV light. Graphene-based sensors also demonstrate high sensitivity and low detection limits, making them suitable for various applications. Although organic materials and hybrid structures, such as metal–organic frameworks (MoFs) and conducting polymers, face challenges related to stability and sensitivity at room temperature, they hold potential for future advancements. Optically activated gas sensors incorporating metal oxides benefit from photoactive nanomaterials and UV irradiation, further enhancing their performance. This review highlights the potential of the advanced materials in developing the next generation of gas sensors, addressing current research gaps and paving the way for future innovations.

Radiative heat transfer plays a pivotal role in many applications across various length scales, with its behavior significantly altering as systems change from the far‐field to the near‐field regime. In the far‐field, radiative heat transfer is governed by traditional laws such as Planck's and Stefan–Boltzmann's laws, which assume that the gap between objects involved in radiative exchange is larger than the thermal wavelength (λ_th), limiting the energy transfer to propagating electromagnetic waves. However, in the near‐field, where distances are smaller than the λ_th, evanescent wave coupling enables heat transfer rates that exceed the blackbody limit by several orders of magnitude. This near‐field enhancement opens new avenues for nanoscale thermal management, energy harvesting, and radiative cooling applications. This review synthesizes the key developments in radiative heat transfer theories, experimental advancements, and practical applications, spanning from early traditional studies to modern innovations leveraging fluctuational electrodynamics. Material‐specific mechanisms, such as surface phonon polaritons, and their role in enhancing radiative heat transfer are also explored while integrating machine learning techniques to optimize near‐field systems. By highlighting these mechanisms and exploring emerging research directions, this work aims to inspire new researchers to enter this dynamic field and provide a roadmap for advancing next‐generation technologies in energy efficiency and nanoscale thermal management.

Rydberg atoms are neutral atoms excited to high principal quantum number states, which endows them with exaggerated properties such as large electric dipole moments, long lifetimes, and extreme sensitivity to external electromagnetic fields. These characteristics form the foundation of Rydberg atom-based sensors, an emerging class of quantum devices capable of optically detecting electric fields across frequencies from DC to the terahertz regime. Rydberg-based electrometry operates through both Autler–Townes (AT) splitting of resonant Rydberg transitions and Stark-shift measurements for high-frequency or far-detuned fields, enabling broadband field sensing from DC to the THz regime. Using ladder-type electromagnetically induced transparency (EIT) and AT splitting, these sensors enable non-invasive, SI-traceable measurements of field amplitude, frequency, phase, and polarization. Recent developments have demonstrated broadband electric field probes, voltage calibration standards, and compact RF receivers based on thermal vapor cells and integrated photonic architectures. Furthermore, innovations in multi-photon EIT, superheterodyne readout, and multi wave mixing have expanded the dynamic range and bandwidth of Rydberg-based electrometry. Despite challenges related to environmental perturbations, linewidth broadening, and laser stabilization, ongoing advances in atomic control, hybrid photonic integration, and EIT-based readout promise scalable, chip-compatible sensors. This review summarizes the physical principles, experimental progress, and emerging applications of Rydberg atom-based sensing, emphasizing their potential for next generation quantum metrology, wireless communication, and precision field mapping.

This study presents a theoretical framework for a radiative thermal memristor (RTM), utilizing Tungsten-doped vanadium dioxide (WVO) as the phase-change material (PCM) and silicon carbide (SiC) in the far-field regime. The behavior of the RTM is depicted through a Lissajous curve, illustrating the relationship between net flux (Q) and a periodically modulated temperature difference $\Delta$T(t). It is established that temperature variations in the memristance (M) of the RTM form a closed loop, governed by PCM hysteresis. The analysis explores the impact of thermal conductivity contrast (r) and periodic thermal input amplitude ($\theta$) on the Q–$\Delta$T curve and the M–$\Delta$T curve and negative differential thermal resistance (NDTR), revealing notable effects on the curve shapes and the emergence of NDTR. An increasing r leads to changes in the Lissajous curve’s shape and enhances the NDTR influence, while variations in both r and ($\theta$) significantly affect the Q values and Lissajous curve amplitudes. In the M–$\Delta$T curve, the height is linked to thermal conductivity contrast (r), with increasing r resulting in higher curve heights.

Two-dimensional (2D) materials have emerged as promising candidates for next-generation photodetectors due to their atomically thin nature, strong light–matter interactions, mechanical flexibility, and tunable optoelectronic properties. This review presents recent advances in 2D material-based photodetectors, focusing on high-performance devices constructed from Graphene, Transition Metal Dichalcogenide (TMDC), Black phosphorus (BP), MXenes, bismuth and antimony chalcogenides, and tin chalcogenides. Key performance metrics such as responsivity, response speed, detectivity, and mechanical stability are discussed across different spectral regions. The performance, key characteristics, and recent achievements of each of the 2D photodetectors are described in detail. Despite these achievements, challenges such as scalability, stability, and interface engineering remain. This review concludes with insights into current limitations and outlines future directions for the design and development of flexible, high-efficiency, and broadband 2D photodetectors.