Beam steering characteristics in high-power quantum-cascade lasers emitting at∼4.6µm

A beam steering effect of high-power quantum cascade(QC) lasers emitting at 4.6 μm was investigated. The continuous wave(CW) output power of an uncoated, 6-mm-long, 7.5-μm-wide buried-heterostructure QC laser at 25℃ was as high as 854.2 m W. The maximum beam steering angle was offset by ±14.2° from the facet normal(0°) in pulsed mode. The phenomenon was judged explicitly by combining the diffraction limit theory and Fourier transform of the spectra. It was also verified by finite element method software simulation and the calculation of two-dimensional(2 D)effective-index model. The observed steering is consistent with a theory for coherence between the two lowest order lateral modes. Therefore, we have established an intrinsic linkage between the spectral instabilities and the beam steering by using the Fourier transform of the spectra, and further presented an extremely valid method to judge the beam steering. The content of this method includes both three equidistant peak positions in the Fourier transform of the spectra and the beam quality located between once the diffraction limit(DL) and twice the DL.     

Broad gain,continuous-wave operation of InP-based quantum cascade laser at λ~11.8 μm

We demonstrate a broad gain, continuous-wave (CW) operation InP-based quantum cascade laser (QCL) emitting at 11.8 μm with a modified dual-upper-state (DAU) and diagonal transition active region design. A 3 mm cavity length, 16.5 μm average ridge wide QCL with high-reflection (HR) coatings demonstrates a maximum peak power of 1.07 W at 283 K and CW output power of 60 mW at 293 K. The device also shows a broad and dual-frequency lasing spectrum in pulsed mode and a maximum average power of 258.6 mW at 283 K. Moreover, the full width at half maximum (FWHM) of the electroluminescent spectrum measured at subthreshold current is 2.37 μm, which indicates a broad gain spectrum of the materials. The tuning range of 1.38 μm is obtained by a grating-coupled external cavity (EC) Littrow configuration, which is beneficial for gas detection.     

人工智能导游系统的实现

人工智能是国家发展的重要战略方向之一,智慧导游是人工智能的在导游服务方面的应用,已成为当前人们旅游生活的一种需求。文章设计了智慧导游系统的结构布局,功能需求,并对系统的信息触发位置的设计进行了深入研究。通过部署到智能手机端,实现了导游的智慧化功能,经过测试,能够满足游客的旅游需求。对于进一步探讨旅游的人工智能化有一定的借鉴意义。     

CuAlSe2光伏吸收层薄膜的制备

用同族元素Al和Fe取代CulnGaSe2薄膜中的In和Ga元素.采用粉末冶金工艺制备CuAlSe2和CuAlSe2∶Fe光伏吸收层薄膜.依次对薄膜样品进行了表面形貌、化学成分、薄膜厚度、晶体结构和光学特性测试分析.结果表明,退火温度为450℃、500℃、550℃时薄膜的生长特性较好,薄膜较为致密,结晶度较高.薄膜主要为黄铜矿结构,并沿(112)晶相择优生长.CuAlSe2薄膜和CuAlSe2∶Fe薄膜样品的光学吸收系数达到105 cm-1,且随着掺Fe比例增加而增加.未掺杂的薄膜的光学带隙约为1.6 eV,掺Fe薄膜的禁带宽度接近1.8 eV.