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无衍射贝塞尔光束的实现方法 总被引:3,自引:0,他引:3
无衍射光束是一种新兴的光束,它具有很好的应用前景,本文给出了无射贝塞尔光束的理论背景、实现方法及相应实验结果,比较了这些方法的优缺点,提出了无衍射光束的应用范围。 相似文献
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贝塞尔光束的特性及参量的影响 总被引:2,自引:2,他引:0
本文利用数值计算研究了Bessel光束的传播特性及参量对其的影响,发现Bessel光束的最大无 射距离与光矢量横向分量系数kr成 反比,而与光阑半径R成正比。最后,得到了一个计算最大无衍射距离的经验公式。 相似文献
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This letter reports a new current versus voltage model for light-emitting devices with a quantum well where electrons and holes are injected and recombine. The current is entirely caused by the recombination of electrons and holes. Historically, the equation used for light-emitting diodes (LEDs) and laser diodes (LDs) has been the renowned Sah-Noyce-Shockley (SNS) diode equation. In this equation at typical forward bias condition, most of the current is caused by the diffusion of carriers over the depletion region. It is clear that this condition is different from what actually happen in LEDs and LDs. We thus looked into the fundamental of carrier transport and developed a new model for devices with a quantum well. Based on the new model, calculated I-V curves agree well with measurement results of GaN/sapphire LEDs with GaInN quantum wells. In calculation, junction temperature Tj rather than case temperature Tc is used to achieve better agreement. 相似文献
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Bessel光束的传输模型 总被引:2,自引:1,他引:1
研究了参量对Bessel光束性质的影响并发现了参量Kr与无衍射距离之间的关系,进一步建立了Bessel光束的传输模型并用数值误差计算进行了证明。 相似文献
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Semiconductor provides a physics-rich environment to host various quantum light sources applicable for quantum information processing. These light sources are capable of deterministic generation of non-classical photon streams that demonstrate antibunching photon statistics, strong indistinguishability, and high-fidelity entanglement. Some of them have even successfully transitioned from proof-ofconcept to engineering efforts with steadily improving performance[ 1]. Here, we briefly summarize recent efforts and progress in the race towards ideal quantum light sources based on semiconductor materials. The focus of this report will be on group III–V semiconductor quantum dots, defects in wide band-gap materials, emitters in two-dimensional van der Waals layered hosts, and carbon nanotubes, as these systems are well-positioned to benefit from recent breakthroughs in nanofabrication and materials growth techniques. 相似文献
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A true Bessel beam is a family of diffraction-free beams. Thus the most interesting and attractive characteristic of such
beam is non-diffracting propagation. In optics, the comparisons of maximum propagation distance had been done between Bessel
and Gaussian beams by Durnin and Sprangle, respectively. However, the results obtained by them are conflict due to the difference
between their criteria. Because Bessel beams have many potential applications in millimeter wave bands, therefore, it is necessary
and significant that the comparison is carried out at these bands. A new contrast criterion at millimeter wavelengths is proposed
in our paper. Under this criterion, the numerical results are presented and a new conclusion is drawn. 相似文献
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Petr G. Eliseev Piotr Perlin Julien Furioli Philippe Sartori Jian Mu Marek Osiński 《Journal of Electronic Materials》1997,26(3):311-319
We investigate electrical and optical characteristics of Nichia NLPB-500 double-heterostructure blue light-emitting diodes
(LEDs), measured over a wide temperature range from 10 to 300K. Current-voltage characteristics have complex character and
suggest involvement of at least two different tunneling mechanisms. The peak energy of the optical emission follows the applied
bias for voltages between 2.3–2.6 V and can be tuned in large spectral range from 2.3 up to 2.8 eV (yellow to blue). This
behavior can be understood invoking the photon-assisted tunneling model which was previously successfully applied to highly
doped GaAs LEDs. Even at the lowest temperatures, light emission still continues while the increase in the series resistance
does not exceed a few tens of kΩ, which indicates absence of complete carrier freeze-out.
On leave from P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow, Russia
On leave from High Pressure Research Center, Warsaw, Poland 相似文献
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基于我们的工作,本文分析了无衍射光束的物理意义,贝塞耳光束的传输变换和聚焦特性。然后,对与无衍射光束有关的一些易于混淆的概念提出了我们的看法。最后,对主要结果加以总结。 相似文献
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In this paper we present results of the analysis of the thermoreflectance (TR) measurements performed on the high-power laser diodes and laser bar emitting at 808 nm. TR is a modulation technique relying on periodic facet temperature modulation induced by pulsed current supply of the laser. The periodic temperature change of the laser induces variation of the refractive index and consequently modulates probe beam reflectivity. Spatially resolved TR spectroscopy is applied to measure line-scans and maps of temperature distribution at the laser mirrors and emitter facets in laser bar. However, to get the absolute values of temperatures, TR needs calibration. Different calibration methods, such as μ-Raman spectroscopy and in situ determination of TR coefficient (CTR), will be discussed. The knowledge of temperature distribution at laser facets gives insight into thermal processes occurring at devices’ facets and consequently leads to the increased reliability and substantially longer lifetimes of such structures. 相似文献
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The progression of carrier confinement from quantum wells to quantum dots has received considerable interests because of the potential to improve the semiconductor laser performance at the underlying physics level and to explore quantum optical phenomena in semiconductors. Associated with the transition from quantum wells to quantum dots is a switch from a solid-state-like quasi-continuous density of states to an atom-like system with discrete states. As discussed in this paper, the transition changes the role of the carrier interaction processes that directly influence optical properties. Our goals in this review are two-fold. One is to identify and describe the physics that allows new applications and determines intrinsic limitations for applications in light emitters. We will analyze the use of quantum dots in conventional laser devices and in microcavity emitters, where cavity quantum electrodynamics can alter spontaneous emission and generate nonclassical light for applications in quantum information technologies. A second goal is to promote a new connection between physics and technology. This paper demonstrates how a first-principles theory may be applied to guide important technological decisions by predicting the performances of various active materials under a broad set of experimental conditions. 相似文献
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GaN-based blue light-emitting diodes (LEDs) on various patterned sapphire substrates (PSSs) are investigated in detail. Hemispherical and triangular pyramidal PSSs have been applied to improve the performance of LEDs compared with conventional LEDs grown on planar sapphire substrate. The structural, electrical, and optical properties of these LEDs are investigated. The leakage current is related to the crystalline quality of epitaxial GaN films, and it is improved by using the PSS technique. The light output power and emission efficiency of the LED grown on triangular pyramidal PSS with optimized fill factor show the best performance in all the samples, which indicates that the pattern structure and fill factor of the PSS are related to the capability of light extraction. 相似文献
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A review of applications of double-discharge circuits based on generators with inductive energy storage (IES) and semiconductor opening switches (SOS) for efficient excitation of different gas lasers is presented. Using a pre-pulse-sustainer circuit technique based on inductive energy storage and semiconductor opening switch generators allows the formation of a pre-pulse with high amplitude and short rise-time and provides a sharp increase of discharge current which significantly improves discharge stability and life-time of the volume discharge in gas mixtures containing halogens. A pre-pulse with high pumping power forms a high-density discharge plasma and an inversion population in gas mixtures under study within ∼10 ns and provides both early onset of lasing and conditions for efficient excitation of an active medium from the storage capacitor. As a result, pulse duration, output energy and efficiency of the lasers under study were improved. 相似文献