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Sensitivity of on-line wavelength during retrieval of atmospheric CO2 vertical profile

Ailin Liang, Xin Ma, Ge Han, Gong Wei, and Chengzhi Xiang

Doc ID: 236724 Received 25 Mar 2015; Accepted 15 May 2015; Posted 15 May 2015  View: PDF

Abstract: Accurately measuring the differential molecular absorption cross section is the key to obtain high precision concentration of atmospheric trace gases in differential absorption lidar (DIAL) system. However, the CO2 absorption line is meticulous at 1.6 µm, which easily translates and broadens because of the change of temperature and pressure. Hence, measuring the vertical profile of atmospheric temperature and pressure to calculate the vertical profile ofCO2weight parameter is necessary. In general, measuring atmospheric temperature and pressure has a certain amount of uncertainty. Therefore, this study proposes a concept of balanced on-line wavelength, where the differential molecular absorption cross section is larger and the CO2 weight parameter is insensitive to the uncertainty of atmospheric temperature and pressure. In this study, we analyzed the influence of uncertainty on CO2 weight parameter at every preselected wavelength, as well as determined an appropriate wavelength near one of the absorption peaks. Result shows that 1572.023 nm should be one of the appropriate balanced on-line wavelengths. The measurement errors of the mixing ratio of CO2 molecule in this wavelength are only 0.23% and 0.26%, which are caused by 1 K temperature error and 1 hPa pressure error, respectively. This achievement of balanced on-line wavelength will not only depress the requirement of laser’s frequency stabilization, but also the demand of measurement precision of atmospheric temperature and pressure profile. Furthermore, this study can achieve the exact measurement of the vertical profile of atmospheric CO2 based on independent differential absorption laser.

Laser-induced Controllable Chirped-Pitch Circular Surface-Relief Diffraction Gratings on Azo-Glass

Ribal Georges Sabat and James Leibold

Doc ID: 235622 Received 04 Mar 2015; Accepted 14 May 2015; Posted 15 May 2015  View: PDF

Abstract: Chirped-pitch nano-scale circular surface-relief diffraction gratings were photo-inscribed on thin films of a Disperse Red 1 functionalized material using a holographic technique. A truncated conical mirror splits and redirects a converging or diverging laser beam resulting in an interference pattern of concentric circles with a chirped-pitch that can be controlled by varying the wave front curvature. The resulting circular gratings have a diameter of 12 mm and have the advantage of being produced in a fast, single-step procedure with no requirement for a master grating, photo-mask or milling equipment.

E-Shaped Wideband Plasmonic Nantennas with Linear and Dual-Linear Polarizations

Mohamed Bakr, Ezzeldin Soliman, and Mohamed El Sherif

Doc ID: 224352 Received 03 Oct 2014; Accepted 13 May 2015; Posted 14 May 2015  View: PDF

Abstract: In this paper we present a novel nano-antenna (nantenna) design for energy harvesting. The nantenna has an “E” shape and is placed on a SiO2 substrate. Its operation is based on the excitation of Surface Plasmon Polaritons (SPPs) through the gold arms of the E-shape. By varying the lengths and widths of the arms, two overlapping working bandwidths can be achieved. This results in a wideband behavior characterized by a Full Width Half Maximum (FWHM) of about 2.2 µm centered around 3.6 µm. Two orthogonal E-nantennas are placed perpendicular to each other to realize a dual-polarized nantenna. This nantenna can receive the two incident polarizations at two separate gap locations with very high isolation. The proposed structure can be used in several energy harvesting applications, such as scavenging the infrared heat from the Earth and other hot objects, in addition to optical communications.

A crosstalk-free integral imaging 3D display based on a pyramid pinhole array

Qiong-Hua Wang, Huan Deng, Fei Wu, Cheng-Gao Luo, and Yao Liu

Doc ID: 236405 Received 23 Mar 2015; Accepted 13 May 2015; Posted 14 May 2015  View: PDF

Abstract: We propose a crosstalk-free integral imaging 3D display based on a pyramid pinhole array. The pyramid pinhole array is used to provide a point light source array. Since the generated point light source array is behind a transmission-type display panel which displays elemental image array, the pseudoscopic problem can be resolved. By setting the appropriate parameters of pyramid pinhole array, the crosstalk can be eliminated. We experimentally verify the reconstruction of the orthoscopic and crosstalk-free 3D images using the proposed 3D display.

Propagation of high power fiber laser with high order mode content

Rumao Tao, Long Huang, Pu Zhou, Lei Si, and Zejin Liu

Doc ID: 235522 Received 03 Mar 2015; Accepted 11 May 2015; Posted 13 May 2015  View: PDF

Abstract: Propagation characteristics of high power fiber laser with high order mode (HOM) content are studied numerically for the first time. The effect of HOM on the propagation property is evaluated by the power in the bucket (PIB) metric. It is shown that PIB is mainly dependent on HOM content rather than the relative phase between fundamental mode and HOM. The PIB in free space is more than 80% when the power in the HOM is controlled to be less than 50% at 5km. The relative phase impacts the peak position and concentration of the far-field intensity distribution. If adaptive optics system is used to correct the peak intensity deviation, the results indicate that there exists an optimization of PIB as relative phase increases. Such effect is weakened when propagating in turbulence. Compared to the laser beams without HOM, laser beams with HOM content are less influenced by the turbulence and can reduce average intensity fluctuation. The results may be useful in design of high power fiber laser system.

Canonical Logic Units using Bidirectional Four-Wave Mixing in Highly Nonlinear Fiber

Xinliang Zhang, Dong wenchan, Hou Jie, yasmeen salman, and Shelan Tawfeeq

Doc ID: 235596 Received 20 Mar 2015; Accepted 10 May 2015; Posted 12 May 2015  View: PDF

Abstract: All-optical canonical logic units (CLUs) at 40 Gb/s using bidirectional four-wave mixing (FWM) in a highly nonlinear fiber (HNLF) are proposed and experimentally demonstrated. Clear temporal waveforms and correct pattern streams are successfully observed in the experiment. This scheme can reduce the amount of nonlinear devices and enlarge the computing capacity compared with general ones.

Arbitrary and reconfigurable optical vortex generation: a high-efficiency technique using director-varying liquid crystal fork gratings

Wei Hu, Bingyan Wei, Wei Ji, Peng Chen, Shijun Ge, Fei Xu, Vladimir Chigrinov, and Yanqing Lu

Doc ID: 236269 Received 23 Mar 2015; Accepted 07 May 2015; Posted 08 May 2015  View: PDF

Abstract: A high efficient technique for optical vortex (OV) generation is proposed and demonstrated. The technique is based on liquid crystal fork gratings with space-variant azimuthal orientations, which are locally controlled via polarization-sensitive alignment layers. Thanks to the optical rewritability of the alignment agent and the dynamic image generation of the digital micro-mirror device, fork gratings can be instantly and arbitrarily reconfigured. Corresponding optical vortices carrying arbitrary azimuthal and radial indices are demonstrated with a conversion efficiency of 98.5%, exhibiting features of polarization control and electrical switching. The technique may pave a bright road towards OV generation, manipulation and detection.

Ghost imaging for an axially moving target with an unknown constant speed

Xiaohui Li, chenjin Deng, Mingliang Chen, Wenlin Gong, and Shensheng Han

Doc ID: 236857 Received 25 Mar 2015; Accepted 29 Apr 2015; Posted 05 May 2015  View: PDF

Abstract: The influence of the target’s axial motion to ghost imaging (GI) is investigated. Both the analytical and experimental results show that the axial relative motion between the target and the source of GI system will lead to the degradation of transverse resolution. To overcome the motion blur, we propose a deblurring method based on speckle-resizing and speed retrieval, and validate experimentally its effectiveness for an axially moving target with an unknown constant speed. The results demonstrated here will be very useful to forward-looking ghost imaging remote sensing.

73 nJ、109 fs Yb-doped fiber laser at 19 MHz repetition rate in amplifier similariton regime

Yizhou Liu, Yifan Cui, Jian Zhang, Aimin Wang, and Zhigang Zhang

Doc ID: 232649 Received 20 Jan 2015; Accepted 02 Apr 2015; Posted 15 Apr 2015  View: PDF

Abstract: We report femtosecond pulse generation in an amplifier similariton oscillator and a pre-chirped fiber amplifier system. The final output power is 1.4 W fundamental repetition rate is 19.1 MHz after a single state fiber amplifier. The pulse width is 109fs.

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