This Review summarizes the developments in Cerenkov imaging and highlights how advances in nanotechnology and materials science have opened new avenues for basic and applied sciences using Cerenkov luminescence. The characteristic blue glow of Cerenkov luminescence (CL) arises from the interaction between a charged particle travelling faster than the phase velocity of light and a dielectric medium, such as water or tissue. As CL emanates from a variety of sources, such as cosmic events, particle accelerators, nuclear reactors and clinical radionuclides, it has been used in applications such as particle detection, dosimetry, and medical imaging and therapy. The combination of CL and nanoparticles for biomedicine has improved diagnosis and therapy, especially in oncological research. Although radioactive decay itself cannot be easily modulated, the associated CL can be through the use of nanoparticles, thus offering new applications in biomedical research. Advances in nanoparticles, metamaterials and photonic crystals have also yielded new behaviours of CL. Here, we review the physics behind Cerenkov luminescence and associated applications in biomedicine. We also show that by combining advances in nanotechnology and materials science with CL, new avenues for basic and applied sciences have opened.

/pdf/utilizing-the-power-of-cerenkov-light-with-nanotechnology-2fbljzfe5c.pdf

Utilizing the power of Cerenkov light with nanotechnology.

We review the research progress in reversed Cherenkov radiation in double-negative metamaterials (DNMs) starting from the first experimental verification of the DNMs reported in 2001, including theories, numerical computation and simulation and experiments. We also discuss the potential applications to particle detectors and highpower microwave or millimeter-wave devices, including the oscillators and amplifiers, and the formidable challenges needed to be resolved before the benefits of using such artificial materials can be harvested. Corresponding author: Z. Y. Duan (zhyduan@uestc.edu.cn).

/pdf/research-progress-in-reversed-cherenkov-radiation-in-double-2xw9x3bfql.pdf

Research Progress in Reversed Cherenkov Radiation in Double-Negative Metamaterials

Plasmonics and metamaterials have attracted considerable attention over the past decade, owing to the revolutionary impacts that they bring to both the fundamental physics and practical applications in multiple disciplines Although the two fields initially advanced along their individual trajectories in parallel, they started to interfere with each other when metamaterials reached the optical regime The dynamic interplay between plasmonics and metamaterials has generated a number of innovative concepts and approaches, which are impossible with either area alone This review presents the fundamentals, recent advances and future perspectives in the emerging field of plasmonic metamaterials, aiming to open up new exciting opportunities for nanoscience and nanotechnology

Plasmonic Metamaterials

Reversed Cherenkov radiation is the exotic electromagnetic radiation that is emitted in the opposite direction of moving charged particles in a left-handed material. Reversed Cherenkov radiation has not previously been observed, mainly due to the absence of both suitable all-metal left-handed materials for beam transport and suitable couplers for extracting the reversed Cherenkov radiation signal. In this paper, we develop an all-metal metamaterial, consisting of a square waveguide loaded with complementary electric split ring resonators. We demonstrate that this metamaterial exhibits a left-handed behaviour, and we directly observe the Cherenkov radiation emitted predominantly near the opposite direction to the movement of a single sheet electron beam bunch in the experiment. These observations confirm the reversed behaviour of Cherenkov radiation. The reversed Cherenkov radiation has many possible applications, such as novel vacuum electronic devices, particle detectors, accelerators and new types of plasmonic couplers.

Observation of the reversed Cherenkov radiation

In this paper, we present the design of a microwave generator using metamaterials (MTMs) in a negative index waveguide interacting with a high-power electron beam. The microwave structure is formed by inserting two MTM plates loaded with complementary split-ring-resonators (CSRRs) into a rectangular waveguide. Electromagnetic simulations using the high-frequency structure simulator code confirm the presence of a negative index TM-like mode suitable for use in a backward-wave oscillator (BWO). Particle-in-cell (PIC) simulations using the computer simulation technology (CST) Particle Studio code are performed to evaluate the efficiency of an S-Band MTM-based BWO (MTMBWO) excited by a 500 keV, 80-A electron beam. After about 250 ns, the MTMBWO reaches a saturated output power of 5.75 MW with an efficiency of 14% at a frequency near 2.6 GHz. The MTMBWO is also modeled by representing the MTM plates, which consist of CSRRs, as dielectric slabs whose effective permittivity is given by a Lorentzian model. The dielectric slab model is also simulated with the CST PIC code and shows good qualitative agreement with the simulations including the CSRR loaded plates. A cold test structure was fabricated from brass to test the theoretical predictions of the microwave transmission versus frequency of the negative index waveguide. Test results using a vector network analyzer showed very good agreement with the simulations for the excitation of the negative index TM-like mode near 2.6 GHz. The proposed structure appears to be promising for use in a MTMBWO high-power microwave generator.

Design of a Metamaterial-Based Backward-Wave Oscillator

We report on a design of a TM‐mode based metamaterial‐loaded waveguide. Network analyzer measurements demonstrated a left‐handed propagation region for the TM11 mode at around 10 GHz. A beamline experiment was performed with the metamaterial‐loaded waveguide. In this experiment, a 6 MeV electron beam passes through the waveguide and generates a wakefield, via the Cherenkov radiation mechanism. We detected a signal in the left‐handed frequency band at 10 GHz. This is an indirect demonstration of reverse Cherenkov radiation as discussed in several papers. Cherenkov radiation in artificially constructed materials (metamaterials, MTM) can provide unusual, engineered features that can be advantageous for particle detector design.

Observation of Wakefield Generation in Left-Handed Band of Metamaterial-Loaded Waveguide

Metamaterials are artificial periodic structures made of small elements and designed to obtain specific electromagnetic properties. As long as the periodicity and the size of the elements are much smaller than the wavelength of interest, an artificial structure can be described by a permittivity and permeability, just like natural materials. When the permittivity and permeability are simultaneously negative in some frequency range, the metamaterial is called double negative or left‐handed and has some unusual properties. Left‐handed metamaterials (LHM) have potential applications in active and passive devices at millimeter waves and at much higher frequencies. Waveguides loaded with metamaterials are of interest because the metamaterials can change the dispersion relation of the waveguide significantly. Slow backward waves can be produced in a LHM‐loaded waveguide without corrugations. The dispersion relation of a LHM‐loaded waveguide has several interesting frequency bands which are described. Left‐hande...

W. Gai

Papers

Observation of Wakefield Generation in Left-Handed Band of Metamaterial-Loaded Waveguide

Left‐Handed Structures for Accelerator Applications