Graphene Q-Switched Cr:ZnSe Laser

Wang, Zhaowei; Chen, Xiufang; He, Jingliang; Xu, Xiangang; Zhang, Baitao; Yang, Kejian; Wang, Ruihua; Liu, Xun-Min

doi:10.1109/jqe.2015.2410288

Cited by 24 publications

(24 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[54] The N-methoxy amide directing group was crucial for the Rh(III)-catalyzed C(sp 2 )–H activation. The authors used iodosylbenzene to oxidize hydroquinones to generate quinones in situ .…”

Section: Rhodium Catalysismentioning

confidence: 99%

A Simple and Versatile Amide Directing Group for C−H Functionalizations

et al. 2016

View full text Add to dashboard Cite

Achieving selective C–H activation at a single and strategic site in the presence of multiple C–H bonds can provide a powerful and generally useful retrosynthetic disconnection. In this context, the directing group serves as a compass to guide the transition metal to C–H bonds using distance and geometry as powerful recognition parameters to distinguish between proximal and distal C–H bonds. However, the installation and removal of directing groups is a practical drawback. To improve the utility of this approach, one can seek solutions in three directions. First, simplifying the directing group; Second, use of common functional groups or protecting groups as directing groups; Third, attaching the directing group to substrates via a transient covalent bond to render directing groups catalytic. This review describes the rational development of an extremely simple and yet broadly applicable directing group for Pd(II), Rh(III) and Ru(II) catalysts, namely, the N-methoxy amide (CONHOMe). Through collective efforts in the community, a wide range of C–H activation transformations using this type of simple directing groups has been developed.

show abstract

Section: Rhodium Catalysismentioning

confidence: 99%

A Simple and Versatile Amide Directing Group for C−H Functionalizations

et al. 2016

View full text Add to dashboard Cite

show abstract

“…19 Eventually, we wish to derive an equation expressing R spon in terms of J. Let us analyze the carrier recombination process inside the quantum well by means of the traditional ABC model for simplicity 14 (although the traditional ABC model somewhat fails to explain the "efficiency droop" phenomenon of InGaN-based MQW LEDs), namely J/qd = An + Bn 2 + Cn 3 , where A and C represent Shockley-Read-Hall (SRH) and Auger coefficients; q the elementary charge; d the thickness of the MQW. Solving this ABC model directly for deriving a formula expressing n in terms of J, however, is quite complicated, prompting us to seek another approach instead.…”

Section: Theorymentioning

confidence: 99%

On a relationship among optical power, current density, and junction temperature for InGaN-based light-emitting diodes

et al. 2017

View full text Add to dashboard Cite

Theories of spontaneous emission rates and carrier recombination mechanisms for multiple-quantum-well InGaN-based blue light-emitting diodes (LEDs) have been carefully studied. A relationship among the optical power, the current density, and the temperature (heat-sink temperature or p-n junction temperature) is identified, and an optical-electrical-thermal model (OETM) is proposed. Thereafter, spectral measurements have been carried out to confirm the validity of this OETM. Results show that measured optical powers under various current densities and heat-sink temperatures agree satisfactorily with those determined by the OETM. Furthermore, the traditional forward-voltage method (FVM) has also been carried out for comparison. Junction temperatures determined by this OETM is in accordance with those measured by the FVM. Therefore, this model can serve as an alternative tool for fast estimating junction temperatures after relevant fitting coefficients having been determined.

show abstract

“…A vertically uniform carrier distribution among the QWs is a challenge in all GaN-based light-emitters 83,84 due to the large difference between the activation energy of donor and acceptor impurities 85 , the strong imbalance between electron and hole mobilities 86 , the large band offsets and, possibly even more critical, the spontaneous and piezoelectric polarization effects at heterointerfaces 87,88 . In order to maximize the radiative recombination in the QWs, one should minimize current crowding 89,90 as well as carrier leakage beyond the active region, which can involve both electrons [91][92][93] and holes 94 and could be enhanced by Auger 95,96 and excited subband recombination 97 . Electrons can be prevented from leaking into the p-GaN layers by inserting an energy barrier in the conduction band between QWs and p-layers, a socalled electron-blocking layer (EBL).…”

Section: Carrier Transport and Optical Gainmentioning

confidence: 99%

Progress and challenges in electrically pumped GaN-based VCSELs

et al. 2016

View full text Add to dashboard Cite

The Vertical-Cavity Surface-Emitting Laser (VCSEL) is an established optical source in short-distance optical communication links, computer mice and tailored infrared power heating systems. Its low power consumption, easy integration into two-dimensional arrays, and low-cost manufacturing also make this type of semiconductor laser suitable for application in areas such as high-resolution printing, medical applications, and general lighting. However, these applications require emission wavelengths in the blue-UV instead of the established infrared regime, which can be achieved by using GaN-based instead of GaAs-based materials. The development of GaN-based VCSELs is challenging, but during recent years several groups have managed to demonstrate electrically pumped GaN-based VCSELs with close to 1 mW of optical output power and threshold current densities between 3-16 kA/cm 2 . The performance is limited by challenges such as achieving high-reflectivity mirrors, vertical and lateral carrier confinement, efficient lateral current spreading, accurate cavity length control and lateral optical mode confinement. This paper summarizes different strategies to solve these issues in electrically pumped GaN-VCSELs together with state-of-the-art results. We will highlight our work on combined transverse current and optical mode confinement, where we show that many structures used for current confinement result in unintentionally optically anti-guided resonators. Such resonators can have a very high optical loss, which easily doubles the threshold gain for lasing. We will also present an alternative to the use of distributed Bragg reflectors as high-reflectivity mirrors, namely TiO2/air high contrast gratings (HCGs). Fabricated HCGs of this type show a high reflectivity (>95%) over a 25 nm wavelength span.

show abstract

Graphene Q-Switched Cr:ZnSe Laser

Cited by 24 publications

References 24 publications

A Simple and Versatile Amide Directing Group for C−H Functionalizations

A Simple and Versatile Amide Directing Group for C−H Functionalizations

On a relationship among optical power, current density, and junction temperature for InGaN-based light-emitting diodes

Progress and challenges in electrically pumped GaN-based VCSELs

Contact Info

Product

Resources

About