Progress in Quantum Electronics最新文献

The optical microresonators reviewed in this paper are called bottle microresonators because their profile often resembles an elongated spheroid or a microscopic bottle. These resonators are commonly fabricated from an optical fiber by variation of its radius. Generally, variation of the bottle microresonator (BMR) radius along the fiber axis can be quite complex presenting, e.g., a series of coupled BMRs positioned along the fiber. Similar to optical spherical and toroidal microresonators, BMRs support whispering gallery modes (WGMs) which are localized inside the resonator due to the effect of total internal reflection. The elongation of BMRs along the fiber axis enables their several important properties and applications not possible to realize with other optical microresonators. The paper starts with the review of the BMR theory, which includes their spectral properties, slow WGM propagation along BMRs, theory of Surface Nanoscale Axial Photonics (SNAP) BMRs, theory of resonant transmission of light through BMR microresonators coupled to transverse waveguides (microfibers), theory of nonstationary WGMs in BMRs, and theory of nonlinear BMRs. Next, the fabrication methods of BMRs including melting of optical fibers, fiber annealing in SNAP technology, rolling of semiconductor bilayers, solidifying of a UV-curable adhesive, and others are reviewed. Finally, the applications of BMRs which either have been demonstrated or feasible in the nearest future are considered. These applications include miniature BMR delay lines, BMR lasers, nonlinear BMRs, optomechanical BMRs, BMR for quantum processing, and BMR sensors.

The applications of light absorbers concern photodetectors, optical filters, solar applications or flexible electronics. In this review, we will detail the application of such light absorbers and we will develop the main demonstrations of the use of metallic nanoparticles embedded within a host matrix to fabricate coatings aiming at harvesting light. We will explain how chemically synthetized silver nanoparticles of various shapes (spheres, cubes, …) and sizes allow controlling the optical properties of heterogeneous thin film layers. By coupling the optical characterizations with computer modeling, we will describe how the nanoparticles behave both individually and collectively. To control reflected and absorbed light by thin film layers containing nanoparticles several points have to be addressed: the relation between the shape of the nanoparticle and the absorptance of the layer, the interaction of light between nanoparticles and the collective behavior of aggregates.

In this review, we describe dielectric properties of biological tissues and liquids in the context of terahertz (THz) biophotonics. We discuss a model of the THz dielectric permittivity of water and water-containing media, which yields analysis of the relaxation and damped resonant molecules modes. We briefly describe modern techniques of THz spectroscopy and imaging employed in biophotonics with a strong emphasize on a THz time-domain spectroscopy. Furthermore, we consider the methods of sub-wavelength resolution THz imaging and the problem of THz wave delivery to hard to access tissues and internal organs. We consider the THz dielectric properties of biological solutions and liquids. Although strong absorption by water molecules prevents THz-waves from penetration of hydrated tissues and probing biological molecules in aqueous solutions, we discuss approaches for overcoming these drawbacks – novel techniques of freezing and temporal dehydration by application of hyperosmotic agents which have a potential for cancer detection. We review recent applications of THz technology in diagnosis of malignancies and aiding histology paying particular attention to the origin of contrast observed between healthy and pathological tissues. We consider recent applications of THz reflectometry in sensing the thinning dynamics of human pre-corneal tear film. Modern modalities of THz imaging, which relies on the concepts of multi-spectral and multi-temporal domains and employing the principles of color vision, phase analysis and tomography are discussed. Novel methods of THz spectra analysis based on machine learning, pattern recognition, chemical imaging and the revealing of the spatial distribution of various substances in a tissue, are analyzed. Advanced thermal model describing biological object irradiated by THz waves and phantoms mimicking the optical properties of tissues at THz frequencies are presented. Finally, application of the high-resolution THz spectroscopy in analytic chemistry, biology and medicine are described.

Group-III nitrides and their alloys feature direct bandgaps covering a broad range of the electromagnetic spectrum, making them a promising material system for various applications, such as solid state lighting, chemical/biological sensing, water splitting, medical diagnostics, and communications. In recent years, the growth of strain and defect-free group-III nitride vertical nanowires has exploded as an area of research. These nanowires, grown on various unconventional substrates, such as silicon and different metals, demonstrate potential advantages over their planar counterparts, including wavelength tunability to the near infrared and reduced efficiency droop. The low-profile and low power consumption of such nanowires also make them viable candidates for emerging applications, such as the Internet of things and artificial intelligence. Herein, we present a comprehensive review on the recent achievements made in the field of III-nitride nanowires. We compare and discuss the growth conditions and mechanisms involved in fabricating these structures via metalorganic chemical vapor deposition and molecular beam epitaxy. How the unique optical, electrical, and thermal properties of these nanowires are correlated with their growth conditions on various unconventional substrates is discussed, along with their respective applications, including light-emitting diodes, lasers, photodetectors, and photoelectrodes. Finally, we detail the remaining obstacles and challenges to fully exploit the potential of III-nitride nanowires for such practical applications.

Since the first observation of stimulated emission from colloidal quantum dots (CQDs) in year 2000, tremendous progress has been made in developing solution-processed lasers from colloidal semiconductor nanostructures in terms of both understanding the fundamental physics and improving the device performance. In this review paper, we will start with a brief introduction about the fabrication of CQDs and the corresponding electronic structures. The emphasis will be put on the discussion about the optical gain and lasing from colloidal nanostructures including the gain mechanism, the main hurdles against optical gain and lasing as well as strategies to optimize the lasing performance. Afterwards, the recent advances in CQD lasers, exemplified by the achievement of continuous wave lasing, will be presented. Finally, the challenges and a perspective of the future development of lasers based on the colloidal semiconductor nanostructures will be presented.

Intriguing intrinsic properties of light quanta and related topics are reviewed by emphasizing the self-consistency of light-matter interactions and open nano-systems dynamics. It is pointed out that there still remain fundamental and challenging issues related to quantization of a finite nano-system interacting with a massive (i.e., localized) photon field,as well as with a hierarchical or structured phonon field. By using theoretical frameworks developed for an infinite system, some of quantum nature of a finite nano-system are revealed, and it is theoretically shown that dynamic phonon environments and the interplay of coherent and incoherent phonons play an important role in quantum coherent dynamics of electron-hole pairs interacting with massive photon fields.

Ideal integrated light emitters for optical interconnects should be compact in size, high in modulation bandwidth, efficient in energy consumption and tunable in frequency. Nanolasers are excellent candidates for such an application. In this article, we review and offer further in-depth analyses in three key aspects of recent nanolaser research, including second order intensity correlation, g²(τ), characterizations, direct modulation and electromagnetic isolation in a dual nanolaser system. For coherence characterization, we review a technique exploiting not only the photon bunching peak, but also the g²(τ) pulse width to determine the spontaneous emission (SE), amplified SE and lasing regimes of a nanolaser with a high SE factor, β. We show that this technique is applicable for lasers with β′s ranging from 10⁻⁵ to unity. Additionally, we demonstrate the first direct current modulation of an electrically pumped metallo-dielectric nanolaser (MDNL) at 30 MHz. Considering the viability of nanolasers for dense integration, we then review the electromagnetic coupling between two closely spaced MDNLs and identify two practical methods to eliminate such coupling. Lastly, we review the state-of-the-art development in and offer future perspectives on three other important areas of nanolaser research ― integration with silicon photonics, wide-range frequency tuning and dual nanolaser dynamics.

Combustion is one of the most dominant energy conversion processes used in all areas of human life, but global concerns over exhaust gas pollution and greenhouse gas emission have stimulated further development of the process. Lean combustion and exhaust gas recirculation are approaches to improve the efficiency and to reduce pollutant emissions; however, such measures impede reliable ignition when applied to conventional ignition systems. Therefore, alternative ignition systems are a focus of scientific research. Amongst others, laser induced ignition seems an attractive method to improve the combustion process.

In comparison with conventional ignition by electric spark plugs, laser ignition offers a number of potential benefits. Those most often discussed are: no quenching of the combustion flame kernel; the ability to deliver (laser) energy to any location of interest in the combustion chamber; the possibility of delivering the beam simultaneously to different positions, and the temporal control of ignition. If these advantages can be exploited in practice, the engine efficiency may be improved and reliable operation at lean air-fuel mixtures can be achieved, making feasible savings in fuel consumption and reduction in emission of exhaust gasses. Therefore, laser ignition can enable important new approaches to address global concerns about the environmental impact of continued use of reciprocating engines in vehicles and power plants, with the aim of diminishing pollutant levels in the atmosphere. The technology can also support increased use of electrification in powered transport, through its application to ignition of hybrid (electric-gas) engines, and the efficient combustion of advanced fuels.

In this work, we review the progress made over the last years in laser ignition research, in particular that aimed towards realizing laser sources (or laser spark plugs) with dimensions and properties suitable for operating directly on an engine. The main envisaged solutions for positioning of the laser spark plug, i.e. placing it apart from or directly on the engine, are introduced. The path taken from the first solution proposed, to build a compact laser suitable for ignition, to the practical realization of a laser spark plug is described. Results obtained by ignition of automobile test engines, with laser devices that resemble classical spark plugs, are specifically discussed. It is emphasized that technological advances have brought this method of laser ignition close to the application and installation in automobiles powered by gasoline engines. Achievements made in the laser ignition of natural gas engines are outlined, as well as the utilization of laser ignition in other applications. Scientific and technical advances have allowed realization of laser devices with multiple (up to four) beam outputs, but many other important aspects (such as integration, thermal endurance or vibration strength) are still to be solved. Rec