Progress in Quantum Electronics最新文献

The ability to manipulate light at the level of single photons, its elementary excitation quanta, has recently made it possible to produce a rich variety of tailor-made quantum states and arbitrary quantum operations, of high interest for fundamental science and applications. Here we present a concise review of the progress made over the last few decades in the engineering of quantum light states. Although far from exhaustive, this review aims at providing a sufficiently wide and updated introduction that may serve as the entry point to such a fascinating and rapidly evolving field.

Quantum non-Gaussian states of photons and phonons are conclusive and direct witnesses of higher-than-quadratic nonlinearities in optical and mechanical processes. Moreover, they are proven resources for quantum sensing, communication and error correction with diverse continuous-variable systems. This review introduces theoretical analyses of nonclassical and quantum non-Gaussian states of photons and phonons. It recapitulates approaches used to derive operational criteria for photons tolerant to optical losses, their application in experiments and their nowadays extension to quantum non-Gaussian photon coincidences. It extends to a recent comparison of quantum non-Gaussianity, including robustness to thermal noise, and sensing capability for high-quality phononic Fock states of single trapped cooled ions. The review can stimulate further development in the criteria of quantum non-Gaussian states and experimental effort to prepare and detect such useful features, navigating the community to advanced quantum physics and technology.

The research on optical wireless communication (OWC) has been going on for more than two decades. Particularly, visible light communication (VLC), as a means of OWC combining communication with illumination, has been regarded as a promising indoor high-speed wireless approach for short-distance access. Recently, lightwave, millimeter-wave (mmWave), terahertz (THz) and other spectrum mediums are considered as potential candidates for beyond fifth-generation/sixth-generation (B5G/6G) mobile communication networks. On the basis of previous studies, this review focuses on revealing how the research of next-generation OWC technology should be carried out to meet the requirements of B5G/6G for practical deployment. The research, development and engineering transformation of the OWC systems are a paragon of interdisciplinary. It involves a wide discussion on how to build a high-speed, multi-user, full-duplex, white-light OWC system based on existing technologies by showing the innovations and trade-offs at various levels with material, device, air-interface technology, system and network architecture. The compatibility of OWC is emphasized and some advanced heterogeneous OWC systems are presented, which involves the combination or integration of various functions such as sensing, near-infrared (NIR) beam-steering, positioning and coexistence with radio frequency (RF) communication. Finally, several potential directions are pointed out for the actual engineering deployment in the B5G/6G era.

Semiconductor lasers are ubiquitous in modern science and technology for they are compact, fast, and efficient. They require relatively low power and thus are well suited for applications in the information technology. However, in conventional semiconductor lasers, the power required to reach the lasing threshold has a fundamental lower bound determined by the carrier density required to reach population inversion, or the transparency condition. This limitation can be overcome in a new type of laser, a polariton laser, which operates under a different mechanism. Coherent light emission from a polariton laser results from a polariton condensate, which is a coherent, thermodynamically favored many-body state, formed at a much lower carrier density than the population inversion density. Furthermore, since polaritons are matter-light hybrid modes formed via strong coupling between excitons and cavity photons, polariton lasers can be controlled via both the photon and exciton components, allowing greater flexibility in tuning and controlling the mode properties. These prospects have propelled intense research effort on polariton lasers in the past few decades. In this article, we will first review the essential properties of polaritons and polariton lasers, followed by recent developments on polariton lasers with unconventional properties and functionalities, and on new material platforms where room temperature polariton lasers have been demonstrated. We will conclude with a brief discussion on prospects of practical applications of polariton lasers.

Owing to their novel physical properties, semiconductors have penetrated almost every corner of the contemporary industrial system. Nowadays, semiconductor materials and their microelectronic and optoelectronic devices are widely used in civil and military fields. Recently, ultrawide-bandgap (UWBG) semiconductors with bandgaps considerably wider than 3.4 ​eV of GaN, such as aluminium gallium nitride (AlGaN), gallium oxide (Ga₂O₃), and diamond, have attracted increasing attention due to their advantages, including high breakdown field, high stability, and high radiation resistance. In this review, recent research pertaining to UWBG semiconductors in optoelectronics and microelectronics is introduced. Moreover, the challenges and opportunities of UWBG semiconductors are deliberated. It is expected that this review will provide inspiration and insights for further related research.

Chiral organic–inorganic hybrid metal halides (HMHs), as an emerging class of chiral semiconductor materials, have attracted unparalleled interest from multi-purpose perspectives, as a result of their easily accessible solution-grown methods, plentiful chemical structure and composition, as well as unique and exciting optoelectronic properties. Recently, substantial progress has been made in the synthesis of chiral HMHs, spectroscopic characterization and fabrication of optoelectronic devices. Although several reviews about the chiroptical properties and applications of chiral HMHs have been published, the comprehensive summary of the basic structural frameworks, fundamental physics and strategies for the modulation of optical activity, which are vital for the design of chiral HMHs and development of relevant optoelectronic applications, are still insufficient. In this review, we summarize the research progress from fundamentals to applications for the single crystals and thin films of chiral HMHs that are conducive to the development of practical optoelectronic devices. First, diverse structural frameworks and synthetic methods of chiral HMHs are systematically summarized. Afterward, fundamental physics and strategies for the modulation of optical activity as well as their related optoelectronic applications are comprehensively reviewed. Finally, we put forward the current challenges in this rapidly evolving field and present an outlook on future prospects to further develop chiral HMHs for various applications.

The measurement of optical ultrafast laser pulses is done indirectly because the required bandwidth to measure these pulses exceeds the bandwidth of current electronics. As a result, this measurement problem is often posed as a 1-D phase retrieval problem, which is fraught with ambiguities. The phase retrieval method known as ptychography solves this problem by making it possible to measure ultrafast pulses in either the time domain or the frequency domain. One well known algorithm is the principal components generalized projections algorithm (PCGPA) for extracting pulses from Frequency-Resolved Optical Gating (FROG) measurements. Here, we discuss the development of the PCPGA and introduce new developments including an operator formalism that allows for the convenient addition of external constraints and the development of more robust algorithms. A close cousin, the ptychographic iterative engine will also be covered and compared to the PCGPA. Additional developments using other algorithmic strategies will also be discussed along with new developments combining optics and high-speed electronics to achieve megahertz measurement rates.

The concept of tunneling injection was introduced in the 1990's to improve the dynamical properties of semiconductor lasers by avoiding the problem of hot carrier injection which increase the gain nonlinearity and hence limit the modulation capabilities. Indeed, tunneling injection led to record modulation speeds in quantum well lasers. Employing tunneling injection in quantum dot lasers is significantly more complicated. Tunneling injection is based on an energy band alignment between a carrier reservoir and the active region where laser oscillation takes place. However, the inherent inhomogeneity of self-assembled quantum dots prevents an unequivocal band alignment and can cause the tunneling injection process to actually deteriorate the laser performance compared to nominally identical quantum dot lasers that have no tunneling section. Understanding the complex process of tunneling injection in quantum dot lasers requires a comprehensive study where different aspects are analyzed theoretically and experimentally. In this paper we describe the technology of such lasers in the InP material system followed by a microscopic analysis of the detailed electrical characterization which is correlated to the electro-optic properties yields information about the exact carrier transport mechanism at bias levels of almost zero to well above threshold. A tunneling injection quantum dot optical amplifier was used for multi wavelength pump probe characterization from which it is clear why tunneling injection often deteriorates laser performance and determines how to design a structure which can take advantage of tunneling injection. Finally, we present a direct comparison between the modulation response of a tunneling injection quantum dot laser and a twin structure that has no tunneling injection section.

The broad study sheds light on the fundamental tunneling injection process that can guide the design of an optimum laser where tunneling injection will be taken full advantage of and will improve the dynamical properties.

We present a review on the photoionization bands that can be found in the far ultraviolet part of the spectrum using all sapphire cells in absorption experiments with hot alkali vapor. We describe cesium and rubidium dimers which have very pronounced photoionization bands together with bialkali mixtures like KCs and RbCs. We explain the origin of these peculiar bands as special molecular transitions between the ground state of the neutral molecule and exited states of the ionized molecule as a direct ionization process. We also described the diffuse bands as transition from the same ground state molecule to doubly excited molecular state, as an indirect ionization process. Finally, we believe that these two pathways may interfere resulting in a complex structure revealing the observed diffuse bands.