超导理论与应用研究的最新进展

介绍了超导理论与应用研究近况，特别是2001年的最新进展。在高温超导体微观机理的重新认识方面，已有证据显示，在高温超导体中存在很强的电子－声子耦合作用；在新型超导材料探索方面，主要有二硼化镁（MgB2），有机聚合物（P3HT），碳60等。超导材料具有现实和潜在的良好应用前景，特别是在能源、电力、交通、微波通信、计算机、医学和各种检测器等领域。     

布拉格反射波导双光束边发射半导体激光器

报道1种在垂直远场方向上产生2个极窄的稳定对称光斑多量子阱边发射半导体激光器,在其有源区两侧设计布拉格反射波导结构.制备100μm条宽的边发射激光器,在垂直方向±33.4°附近实现2个稳定的7.2°对称的近圆形光斑,对器件镀膜后进行测试,在连续和脉冲工作条件下分别得到1.40,2.26 W的输出,器件的特征温度可达到91K.     

80 Gb/s高速PAM4调制850 nm垂直腔面发射激光器

展示了高速直接调制850 nm氧化物限制垂直腔面发射激光器（VCSEL）的结果。优化设计应变InGaAs/AlGaAs量子阱以实现高微分增益,通过表面刻蚀来调节光子寿命实现响应平坦化。研制的氧化物孔径约7μm的VCSEL具有平坦的频率响应,3 dB调制带宽为24 GHz,相对噪声强度值-155 dB/Hz,未采用任何预加重和均衡技术情况下PAM4调制数据传输速率达80 Gb/s。     

一种基于布拉格反射波导的表面等离子体激光光源（英文）

设计了一种基于布拉格反射波导的新型表面等离子体激光光源。这种光源结构简单,便于集成,可以在室温电泵浦的条件下工作,同时可以输出约毫瓦量级的表面等离子激光,相比于文献报道中纳米尺度的纳瓦级表面等离子体激光光源要高很多。该表面等离子体激光光源发射波长为808 nm,布拉格反射波导所提供的倾斜激光光线在我们设计的准Otto模型中可以直接耦合成为表面等离子体。     

Tapered Bragg reflection waveguide edge emitting lasers with near circular twin-beam emission

An edge emitting laser with two symmetrical near-circular spots located far field （FF） is demonstrated using tapered double-sided Bragg reflection waveguides （BRWs）. The BRWs consist of six pairs of top p-type and bottom n-type A10.Ga0.9 As/A10.3 Ga0.7As Bragg reflectors with a period thickness of 850 nm. The device has a 4° tapered angle configuration and exhibits two stable circular beams with a separation angle of 52°. Typical FF angles of 5.87° and 7.8° in the lateral and vertical directions, respectively, are achieved. The lateral FF angle in the ridged section is independent of the injection current （〉0.8 A） beeause of narrow ridge （-10 μm） confinement. By contrast, the FF angle in the tapered section shows an increase rate of 1.2 1.66°/A. The periodic modulation of the lasing wavelength is observed to be sensitive to self-heating effects.     

高速光子晶体面发射激光器研究进展

光子晶体面发射激光器（PCSEL）利用二维光子晶体光栅的布拉格共振实现面发射激光,具有其独特的优势,包括单模性能、在片测试、高功率、低发散角等。相比垂直腔面发射激光器（VCSEL）,PCSEL有将近两倍的有源区光限制因子,展现出高速运行的潜力。本文探讨了PCSEL的基本结构和工作原理,并详细分析了影响PCSEL激光器实现高速性能的关键因素。随后,文章系统地介绍了近年来研究者们为实现PCSEL高速性能所做的努力,重点聚焦于通过增强PCSEL的面内限制来缩小激光腔,并提供了相关的研究方向和指导。     

1.3μm GaAs基量子点垂直腔面发射激光器结构设计与分析

结合垂直腔面发射激光器（VCSEL）原理以及量子点增益特点，计算了不同结构VCSEL的腔内损耗和量子点的模式增益.分析了激光器阈值特性以及氧化限制层对光损耗的影响.设计了含 氧化限制层的13μm量子点VCSEL结构. 关键词： 量子点 垂直腔面发射激光器 增益     

High beam quality broad-area diode lasers by spectral beam combining with double filters

A modified spectral beam combining(SBC) approach based on double asymmetrical filters was proposed. By using this scheme, the high-order lateral modes at the edge of the far-field pattern can be suppressed in the external cavity, and the beam quality in the slow-axis direction was improved from 16.1 to 13.4 compared to the conventional SBC. In the meanwhile, the electrical-to-optical efficiency from the modified SBC was more than 40% with an output power of 34.1 W, which is similar to that of the conventional SBC.     

High efficiency beam combination of 4.6-μm quantum cascade lasers

The quantum cascade laser （QCL）, a potential laser source for mid-infrared applications, has all of the advantages of a semiconductor laser, such as small volume and light weight, and is driven by electric power. However, the optical power of a single QCL is limited by serious self-heating effects. Therefore, beam combination technology is essential to achieve higher laser powers. In this letter, we demonstrate a simple beam combination scheme using two QCLs to extend the output peak power of the lasers to 2.3 W. A high beam combination efficiency of 89% and beam quality factor of less than 5 are also achieved.     

Tapered Bragg reflection waveguide edge emitting lasers with near circular twin-beam emission简

Experiments on developing a frequency-stabilized 555.8-nm laser are presented. The 555.8-nm laser＇ is obtained by frequency doubling of a l lll.6-mn diode laser through single-passing a periodically poled lithium niobate （PPLN） waveguide. Tile 555.8-nm laser is then locked to a stable high-finesse Fabry Perot （FP） cavity by tile Pound Drever--Hall （PDH） technique. Tile finesse of the cavity is measured by tile heterodyne cavity ring-down spectroscopy technique. The linewidth of the 555.8-nm laser is investigated. Alter the laser is locked, the laser line width is reduced to about 3 kHz. This frequency-stabilized 555.8-nm laser is used in experiments on the laser cooling and trapping of ytterbium atoms to develop an ytterbium optical clock.