Bend-optimized optical fiber with S+C+L bands for FTTH applications

A multi-clad waveguide, which provide more bandwidth for WDM with S+C+L bands, is illustrated in this study. The bending loss is optimized for the FTTH applications. The fiber is manufactured by PCVD process; the test results are identical with the theoretic calculation. This fiber has nearly flat dispersion from 1460 nm to 1625 nm. The MFD at 1310 nm and 1550 nm are 8.2 and 9.4 μm, respectively. Bending loss is less than 0.1 dB/Turn at a bending radius of 7.5 mm. With low-water-peak manufacture technologies, the fiber is suitable for FTTH applications.     

Octave-spanning supercontinuum generation of vortices in an As2S3 ring photonic crystal fiber

We propose As(2)S(3) ring photonic crystal fiber (PCF) for supercontinuum generation of optical vortex modes. Due to the large material index contrast between As(2)S(3) and air holes in the designed ring PCF, there is a two-orders-of-magnitude improvement of the difference between the effective refractive indices of different vortex modes compared with regular ring fiber. The design freedom of PCFs enables a low dispersion (<60 ps/nm/km variation in total) over a 522 nm optical bandwidth. Moreover, the vortex mode has a large nonlinear coefficient of 11.7/W/m at 1550 nm with a small confinement loss of <0.03 dB/m up to 2000 nm. An octave-spanning supercontinuum spectrum of the vortex mode is generated from 1196 to 2418 nm at -20 dB by launching a 120 fs pulse with a 60 W peak power at 1710 nm into a 1 cm long As(2)S(3) ring PCF.     

Fatigue properties of a S45C steel subjected to ultrasonic nanocrystal surface modification

An ultrasonic nanocrystal surface modification (UNSM) technique, at 3 different vibration strike numbers (34,000 times/mm², 45,000 times/mm², 68,000 times/mm²) was used to modify the surface structure and properties of S45C. These three process conditions respectively produced 2 μm, 12 μm and 30 μm nanocrystal layers. UNSM technique improves the following mechanical properties: microhardness, surface roughness, and compressive residual stress. Also, fatigue life increased with the vibration strike number. UNSM C3 (with the vibration strike number of 68,000 times/mm²) has improved the fatigue strength by as much as 33% for S45C. Optical microscope pictures show that cracks usually initiate from intergranular microcracks on the surface and then extend along the tip traces of UNSM which are considered as process defects. A simple math model (tearing adhesive plaster model) has been made to analyze the initiation and growth of cracks. Though most of the cracks initiate at the surface of specimens, surface nanocrystal layers can help to retard crack initiation. In S45C, the efficiency of crack resistance is more than 48%.the vibration strike number     

宽调谐高效率的BBO光参量振荡器

本文报道用354.7nm泵浦的单共振BBO脉冲光参量振荡器在413～661nm和2513～765nm波段内获得了可调谐的振荡输出,最高总能量转换效率达52％;文中还讨论了输出特性。     

Supercontinuum generation in square photonic crystal fiber with nearly zero ultra-flattened chromatic dispersion and fabrication tolerance analysis

This paper presents a simple index-guiding square photonic crystal fiber (SPCF) where the core is surrounded by air holes with two different diameters. The proposed design is simulated through an efficient full-vector modal solver based on the finite difference method with anisotropic perfectly matched layers absorbing boundary condition. The nearly zero ultra-flattened dispersion SPCF with low confinement loss, small effective area as well as broadband supercontinuum (SC) spectra is targeted. Numerical results show that the designed SPCF has been achieved at a nearly zero ultra-flattened dispersion of 0 ± 0.25 ps/(nm·km) in a wavelength range of 1.38 μm to 1.89 μm (510 nm band) which covers E, S, C, L and U communication bands, a low confinement loss of less than 10⁻⁷ dB/m in a wavelength range of 1.3 μm to 2.0 μm and a wide SC spectrum (FWHM = 450 nm) by using picosecond pulses at a center wavelength of 1.55 μm. We then analyze the sensitivity of chromatic dispersion to small variations from the optimum value of specific structural parameters. The proposed index-guiding SPCF can be applicable in supercontinuum generation (SCG) covering such diverse fields as spectroscopy applications and telecommunication dense wavelength division multiplexing (DWDM) sources.     

Ultra-wideband spectral analysis using S2 technology

This paper outlines the efforts to develop an ultra-wideband spectrum analyzer that takes advantage of the broad spectral response and fine spectral resolution (∼25 kHz) of spatial-spectral (S2) materials. The S2 material can process the full spectrum of broadband microwave transmissions, with adjustable time apertures (down to 100 μs) and fast update rates (up to 1 kHz). A cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm is used as the core for the spectrum analyzer. Efforts to develop novel component technologies that enhance the performance of the system and meet the application requirements are discussed, including an end-to-end device model for parameter optimization. We discuss the characterization of new ultra-wide bandwidth S2 materials. Detection and post-processing module development including the implementation of a novel spectral recovery algorithm using field programmable gate array technology (FPGA) is also discussed.     

双狭缝透射光栅软X光时空分辨谱仪

 利用双狭缝、透射光栅配亚仟X光条纹相机做了具有一维空间、时间和能谱分辨的三维软X光测量仪器(双狭缝透射光栅软X光时空分辨谱仪), 并成功地获得了金盘靶的N带X光(中心波长1.7nm)时空分辨图象 。该仪器空间分辨可达23μm, 时间分辨可达003ns, 能谱分辨(当源大小为100～300μm时对波长1.7nm的X光)可达0.4～ 0.7nm, 只需稍加改动, 即可用于其它波段的X光测量。     

Picosecond laser cutting and drilling of thin flex glass

We investigate the feasibility of cutting and drilling thin flex glass (TFG) substrates using a picosecond laser operating at wavelengths of 1030 nm, 515 nm and 343 nm. 50 μm and 100 μm thick AF32^®Eco Thin Glass (Schott AG) sheets are used. The laser processing parameters such as the wavelength, pulse energy, pulse repetition frequency, scan speed and the number of laser passes which are necessary to perform through a cut or to drill a borehole in the TFG substrate are studied in detail. Our results show that the highest effective cutting speeds (220 mm/s for a 50 μm thick TFG substrate and 74 mm/s for a 100 μm thick TFG substrate) are obtained with the 1030 nm wavelength, whereas the 343 nm wavelength provides the best quality cuts. The 515 nm wavelength, meanwhile, can be used to provide relatively good laser cut quality with heat affected zones (HAZ) of <25 μm for 50 μm TFG and <40 μm for 100 μm TFG with cutting speeds of 100 mm/s and 28.5 mm/s, respectively. The 343 nm and 515 nm wavelengths can also be used for drilling micro-holes (with inlet diameters of ⩽75 µm) in the 100 μm TFG substrate with speeds of up to 2 holes per second (using 343 nm) and 8 holes per second (using 515 nm). Optical microscope and SEM images of the cuts and micro-holes are presented.     

基于有限元软件分析碳纳米管的最佳阵列密度

利用有限元软件ANSYS,对碳纳米管的最佳阵列密度进行了分析。针对碳纳米管阵列静电场分布的特点,建立了碳纳米管的模型,确定了模型的边界条件。为了便于对计算结果进行对照,在分析时采用的参数是:阵列周期T=2000nm,单根碳纳米管长度L=1μm,顶端半径r=2nm。通过计算得到了单根碳纳米管的场增强因子为321。在长度L和顶端半径r不变的情况下,使用了参数化设计语言,计算了在不同周期(200～4000μm)下碳纳米管场增强因子随周期变化的情况,进一步利用Fowler Nordheim函数得到最佳阵列周期(1600μm)。结果证明,利用有限元软件,其分析过程不仅正确性,而且实用,并且为此类问题的解决提供了一个通用的方法。     

Resolution Improvement in Optical Coherence Tomography with Segmented Spectrum Management

We demonstrate resolution improvement in an optical coherence tomography (OCT) system with multiple scans of segmented spectral bands and software signal processing. With an effective spectral full-width at half-maximum (FWHM) of 45 nm, centered at 950 nm, we compress the interference fringe FWHM from 31 μm down to 7 μm, which is smaller than the theoretical limit of 8.9 μm if a Gaussian spectral shape is assumed, through the combined effect of dispersion compensation and spectral shaping. With the amplitude adjustments of the OCT images of the segmented spectral bands, side-lobes can be significantly suppressed with a slight increase of the fringe envelope FWHM. With other amplitude adjustments, the envelope FWHM can be reduced to 5.6 μm at the expense of significant side-lobes.     

Synthesis of plate-like Li<Subscript>3</Subscript>PS<Subscript>4</Subscript> solid electrolyte via liquid-phase shaking for all-solid-state lithium batteries

The precursor of plate-like Li₃PS₄ solid electrolyte (75Li₂S?25P₂S₅, SE (LS)), about 3 μm in length, 500 nm in width, and 100–200 nm in thickness, was successfully prepared from Li₂S and P₂S₅ using ethyl propionate (EP) as a synthetic medium via liquid-phase shaking. Upon evacuating at 170 °C, the precursor decomposed to SE (LS), which exhibited ionic conductivity of about 2.0 × 10^?4 Scm^?1 at room temperature. SEM observation revealed that the SE (LS) thus obtained had plate-like morphology with dimension of 3 μm in length, 500 nm in width, and 100–200 nm in thickness. Owing to the nanosized SE (LS), an all-solid-state half-cell using composite anode consisting of 90 wt% LiNi_1/3Mn_1/3Co_1/3O₂ (NMC) and 10 wt% SE (LS) delivered a high capacity up to 130 mAhg^?1(NMC) at the first discharge.     

高效率低阈值Nd:S-FAP晶体激光特性

测量了新型晶体Nd:S-FAP[Nd:Sr₅(PO₄)₃F]的吸收光谱特性,它具有宽的有效吸收带,在575.0nm和805.4nm处有二个强的吸收峰.用可调谐染料激光器测量了575.0nm处的吸收系数为19.7cm^-1,用波长为575.0nm的的染料激光作泵浦源,实现了1.059μm的全偏振光输出,最低闽值为2.5mJ,斜效率为49%.用KTP倍频获得的绿光的波长为0.5295μm,峰值半宽度为1.0nm.     

梳状型高线性度一维位敏检测器

介绍了一种梳状型一维位敏检测器(PSD)的结构,对其工作原理进行了分析.比较测试了这种梳状结构(1mm×12mm)PSD与普通块状型结构(1mm×3mm)PSD的线性度,实验表明:梳状结构的PSD具有极高的线性度(均方根非线性为0.17%F.S)和较小的边缘失真.对影响一维PSD线性度的因素进行了分析,并对结果进行了讨论.     

Demonstration of a no-moving-parts axial scanning confocal microscope using liquid crystal optics

For the first time, to the best of authors’ knowledge, a no-moving-parts axial scanning confocal microscope (ASCM) system is designed and demonstrated using a combination of a large diameter liquid crystal (LC) lens and a classical microscope objective lens. By electrically controlling the 5 mm diameter LC lens, the 633 nm wavelength focal spot is moved continuously over a 48 μm range with a measured 3-dB axial resolution of 3.1 μm using a 0.65 numerical aperture (NA) micro-objective lens. The ASCM is successfully used to image an Indium Phosphide (InP) twin square optical waveguide sample with a 10.2 μm waveguide pitch and 2.3 μm height and width. Using fine analog electrical control of the LC lens, a super-fine sub-wavelength axial resolution of 270 nm is demonstrated. The proposed ASCM can be useful in various precision three-dimensional (3D) imaging and profiling applications.     

利用HITRAN资料研究黑碳和沙尘气溶胶粒子的光学特性

在IDL程序语言中实现Mie理论的数值算法,利用HITRAN资料提供的气溶胶粒子复折射指数,计算分析了沙尘、黑炭2种气溶胶粒子在不同半径（1μm,2.5μm和10μm）时,对波长为400nm和860nm光的散射效率以及散射相函数矩阵元素。结果表明：黑炭与沙尘有明显的光学性质差别,沙尘粒子不仅散射效率大于黑碳,而且后向散射比黑碳粒子强。 2种粒子对400 nm和860 nm太阳光的偏振也不同,可以利用此特性鉴别这2种气溶胶。     

产生蓝色相干辐射和实现Nd:YAG 1.0642μm倍频90°非临界相位匹配的Nb:KTiPO4

本文报道了用熔盐顶部籽晶法生长Nb浓度(0～13)mol%的Nb:KTP晶体的倍频的Ⅱ型相位匹配的截止波长和Nd:YAG 1.0642μm及Nd:YA1O3 1.0795μm激光在这些晶体中倍频的最佳相位匹配角的测量结果.从中可看出,由于Nb5+的引入使KTP晶体倍频的Ⅱ相位匹配的截止波长有效蓝移,目前已使截止波长蓝移至937nm且有效产生468.5nm的倍频蓝光.同时Nb5+的引入使Nd:YAG 1.0642μm激光和Nd:YA1O3倍频的最佳相位匹配方向产生很大的变化,目前已使Nb:KTP晶体倍频的最佳相位匹配方向为θ＝88.32°、Φ＝0°,非常接近于90°非临界相位匹配方向.     

Velocity map imaging study of OCS photodissociation followed by S(1S) autoionization at 157 nm

Atomic sulphur ions (S+) were observed directly by crossing a carbonyl sulphide (OCS) molecular beam with a F2 laser. In this study both S+ ion and electron images were measured using the velocity map imaging technique. The results imply that S+ is produced from the well-known photodissociation of OCS at 157 nm leading to the dominant S(1S) + CO(1Σ+) channel, and then the excited S(1S) atom is directly ionized by another 157 nm photon. Correlated vibrationally resolved angular distributions and internal energy distribution of the CO coproducts are reported here and compared with previous studies. This experiment yields strong and sharp S+ images which may be useful for calibrating any imaging or laser ionization apparatus when using a 157 nm laser. A number of technical aspects such as corrections for partial slicing and imperfect laser polarization are described. Abstraction of product angular distributions using both polarized and unpolarized photolysis lasers is also demonstrated using velocity map imaging.     

掺Er3+光纤环腔激光器的初步研究

本文报道采用环形腔使用偏振灵敏性光纤隔离器(P-SensitiveISO)构成的掺Er³⁺光纤激光器的激光输出特性研究结果.用976nm激光作为泵浦激光获得了0.42mW最大功率、中心波长1.5287μm的激光输出,阈值泵浦功率17mW.在改变腔内光纤偏振控制器(PC)的状态时,输出激光光谱分裂为二个分立的峰值,波长分别为1.5317μm和1.5502μm.     

单模硫系光纤色散特性分析

本文对目前红外光纤研究的热点-硫系光纤独特的色散特性进行理论分析.研究主要针对As2S3光纤的材料特性进行.理论计算和分析显示:As₂S₃光纤的材料色散高达-100ps/km.nm以上,比硅基材料光纤高1～2个数量级,可以与硅基光纤光栅相媲美.特殊的色散特性,预示了硫系光纤及其器件广阔的应用前景.     

Hybrid photonic crystal 1.31/1.55 μm wavelength division multiplexer based on coupled line defect channels

The objective of this paper is to investigate the implementation of a hybrid photonic crystal (PhC) 1.31/1.55 μm wavelength division multiplexer (WDM) and wavelength channel interleaver with channel spacing of roughly 0.8 nm between the operating wavelengths of 1.54-1.56 μm. It is based on 1-D photonic crystal (PhC) structure connected with an output 2-D PhC structure. The power transfer efficiency of the hybrid PhC WDM at 1.31 μm and 1.55 μm were computed by eigen-mode expansion (EME) method to be about 88% at both the wavelengths. The extinction ratios obtained for the 1.31 μm and 1.55 μm wavelengths are − 25.8 dB and − 22.9 dB respectively.