Progress in Quantum Electronics最新文献

Underwater wireless optical communication (UWOC) is an emerging and feasible underwater communication technology and has developed rapidly in recent years. Building a high-performance and practical UWOC system requires comprehensive consideration and optimization design from the device to the system, as well as from the internal modulation to the external environment. This paper provides an overview of the recent developments in UWOC systems, covering aspects about the system transmitters and receivers, advanced modulation formats and underwater channels. Some key technologies to improve transmission capacity of UWOC are classified and summarized to provide guidance for system design. The main challenges and perspectives to achieve a reliable UWOC system are also mentioned. The summary and analysis of these advances and techniques will shed light on the future development of UWOC technology and assist in the construction of the internet of underwater things.

Rectifying antennas are often prensented as a potentiel technological breakthrough for energy harvesting. First theorized in the 1970’s, the downsizing of an antenna coupled with a rectifier has become technologically achievable with the progresses of fabrication techniques such as electron beam or photolithography. However, reaching infrared or visible region of the electromagnetic spectra still entails challenges on the integration of a rectifier operating in the terahertz range. New bottom up approaches are likely to bring a promising solution to this issue. To improve our understanding of the key points of rectifying antennas’ design for the infrared and visible light, and the challenges of device fabrication, this work reviews the progresses of this technology, going back from the first historical RF energy harvesting systems and covering the most innovative trends to this date.

We report on the first watt-level ultrafast laser inscribed Thulium waveguide (WG) lasers. Depressed-index buried channel WGs with a circular cladding (type III) are produced in monoclinic Tm³⁺:KLu(WO₄)₂ crystals. Laser operation is achieved under conventional (³H₆ → ³H₄) and in-band (³H₆ → ³F₄) pumping. In the former case, employing a Raman fiber laser emitting at 1679 ​nm as pump, the continuous-wave Tm channel WG laser generated 1.37 ​W ​at 1915–1923 ​nm with a record-high slope efficiency of 82.7% (with respect to the absorbed pump power), a threshold of only 17 ​mW and a spatially single-mode output with linear polarization. The WG propagation losses were 0.2 ​± ​0.3 ​dB/cm. Passive Q-switching of Tm channel WG lasers is achieved using Cr²⁺:ZnS and Cr²⁺:ZnSe saturable absorbers. With Cr²⁺:ZnS, record-short pulses of 2.6 ns/6.9 ​μJ ​at a repetition rate of 8.0 ​kHz were generated. The developed WGs are promising for compact GHz mode-locked lasers at ~2 ​μm.

In this paper we review the field of terahertz (THz) sources which make use of the nonlinear, stimulated polariton scattering (SPS) process. A historical perspective of the technology is offered, in addition to an investigation of modern SPS-based THz sources. Breakthroughs in these source technologies have coincided with rapid developments in laser technology over the past 10 years. We are now in an age where pulsed SPS-THz sources are generating peak powers in excess of 50 ​kW, and continuous wave SPS-THz sources can be produced using diode pump powers as low as 2.3 ​W. The versatility of this approach to THz generation has enabled the generation of coherent THz radiation across continuous wave (CW), nanosecond-, and picosecond-pulsed modalities, with sources spanning the frequency range 0.5–13 ​THz. Being based on robust and well-developed, crystalline solid-state laser technology, these sources hold great promise as an enabling technology for a plethora of THz applications.

Micro light-emitting diode (micro-LED) display, mainly based on inorganic GaN-based LED, is an emerging technique with high contrast, low power consumption, long lifetime and fast response time compared to liquid crystal display (LCD) and organic light-emitting diode (OLED) display. Therefore, many research institutes and companies have conducted in-depth research on micro-LED in the full-colour display, gradually realizing the commercialization of micro-LED. And the current research results of micro-LED indicate that it can be widely used in display, visible light communication (VLC), biomedicine and other fields. Although micro-LED has broad commercial prospects, it still faces great challenges, such as the effect of size reduction on performance, the realization of high-density integration on a single wafer for independent addressing of full-colour micro-LED display, the improvement of repair technique and yield et al. This paper reviews the key solutions to the technical difficulties of the full-colour micro-LED display. Specifically, this review analyzes and discusses a variety of advanced full-colour micro-LED display techniques with a focus on three aspects: growth technique, transfer printing technique and colour conversion technique. This review demonstrates the opportunities, progress and challenges of these techniques, aiming to guide the development of full-colour micro-LED display.

Ultrafast femtosecond mode-locked fiber laser plays an indispensable role in medical imaging, space ranging, ophthalmology, terahertz spectroscopy, material micromachining, and so on. It’s not only an important tool for people to explore the world, but also a pillar field of laser technology. This review present the generation of femtosecond pulses in ultrafast mode-locked fiber lasers using active, passive, hybrid mode-locking techniques, the emphasis is given to passively mode-locked fiber lasers. In terms of the optimization of femtosecond pulses, we introduce the external compression technique to obtain shorter pulse width, chirped pulse amplification technique to increase pulse energy and obtain high energy femtosecond pulses at the practical band. Furthermore, the coherent beam combination and divided pulse amplification technique to further boost pulse energy are summarized. At the end of this review, we present a detailed overview of the applications of femtosecond pulses including the generation of supercontinuum and tunable femtosecond pulses, and some practical applications. Several perspectives and research directions of femtosecond pulses are also addressed.

Blue LEDs and HEMTs based on III-Nitride have been flourishing commercially across the globe, thanks largely to breakthroughs in the material quality of the wide-bandgap compound semiconductor back in the 1990s. The realizations of white-light LEDs, blu-ray systems, and lately efficient compact chargers have drastically changed the way we live and have contributed tremendously to global energy saving efforts. The maturity and diversity of modern discrete GaN-based devices open up opportunities for an integrated GaN platform with extended functionalities and applications. In this review paper, we present an overview of the monolithic and heterogeneous integration of GaN devices and components. Various methods for the integration of electronic, optoelectronic, and optical components based on GaN are discussed.

This paper reviews the field of microwave photonics instantaneous frequency measurements (IFM). It aims to consolidate the literature, explains the key implementations and reviews the recent developments. Current photonic IFMs are capable of operating over a wide bandwidth with a good resolution. However, their implementations are often based on discrete components and exhibit limited dynamic range and moderate efficiency. Photonic integration and improvements of dynamic range and efficiency are thus necessary, and they are anticipated as the future research directions and developments.