Progress in Quantum Electronics最新文献

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.

The development of the HgCdTe alloy as the most important intrinsic semiconductor for infrared (IR) technology is well established and recognized. In spite of the achievements in material and device quality, the drawbacks still exist due to bulk and surface instability, lower yields and higher costs particularly in fabrication of long wavelength infrared arrays. The difficulties with this material encouraged to research on other compounds to improve device performance.

Since the first paper published by Sakaki and Esaki in 1978 it is well known that InAs and GaSb constitute a nearly lattice-matched material system offering great flexibility in the design of IR optoelectronic devices. After four decades, the III-V type-II superlattice (T2SL) detector technology is under strong development as a possible alternative to HgCdTe. The novel ideas coming in design of detectors have enhanced the position of T2SLs in IR materials detector technology. It appears that T2SLs are especially helpful in the design of unipolar barriers.

In this paper fundamental physical properties of two material systems, HgCdTe and T2SLs, are compared together with their influence on detector performance: dark current density, RA product, quantum efficiency, and noise equivalent different temperature. In comparison with HgCdTe, fundamental properties of T2SLs are inferior. On the other hand, T2SL and barrier detectors have several advantages to include lower tunnelling and surface leakage currents, and suppressed Auger recombination mechanism. Up to date, the promise of superior performance of these detectors has not been realized yet. In the paper we present that the performance of T2SL detectors (dark current, current responsivity, and noise equivalent difference temperature) is lower than bulk HgCdTe photodiodes.

Due to stronger, less ionic chemical bonding of III-V semiconductors, these materials are attractive due to manufacturability and stability. It is also predicted that the interband T2SL quantum cascade devices will outperform the performance of the high operating temperature HgCdTe detectors.

Recent advances in the development of quantum dots (QDs) have offered new possibilities for the exploration of sensors, bio imaging, batteries, electrochemical water splitting and optoelectronic applications because of their intriguing optical, electrical, catalytic and electrochemical properties. Among QDs, atomically thin two-dimensional quantum dots (2D QDs) derived from graphene sheets, transition metal dichalcogenide (TMD) layers and phosphorene have been of considerable interest for the past few years. There have been several intensive studies of carbon QDs, but TMD QDs and heterostructures based on 2D QDs are rapidly advancing. Herein, the synthesis and properties of 2D QDs, particularly carbon and TMD QDs, are reviewed for the recent progress in their application toward electrochemical water splitting, photocatalytic wastewater treatment, supercapacitors, batteries and photodetectors. Moreover, the assembly of such 2D QDs to achieve industrial-scale production and boost their performance in widespread applications is emphasized.