摘要：The energy levels, wave functions and the second-order nonlinear susceptibilities are calculated in GaAs/Al0.2Ga0.8As/Al0.5Ga0.5As asymmetric quantum well （AQW） by using an asymmetric model based on the parabolic and non-parabolic band. The influence of non-parabolicity can not be neglected when analyzing the phenomena in narrow quantum wells and in higher lying subband edges in wider wells. The numerical results show that under double resonance （DR） conditions, the second- order difference frequency generation （DFG） and optical rectification （OR） generation susceptibilities in the AQW reach 2.5019 μm/V and 13.208 μm/V, respectively, which are much larger than those of the bulk GaAs. Besides, we calculate the absorption coefficient of AQW and find out the two pump wavelengths correspond to the maximum absorption, so appropriate pump beams must be selected to generate terahertz （THz） radiation by DFG.

摘要：In this paper,we present the design of a new photonic crystal fiber(PCF)gas sensor for evanescent-field sensing in terahertz(THz)wave *** sensor can be used to identify the gas,and its size is very large,so that it is beneficial to fill it with the test *** on simulation,we demonstrate that the gas sensor using PCFs with four noncircular large holes in the cladding has high sensitivity and low loss,the confinement loss is less than 0.007 dB/m,and the bending loss is very *** new PCF gas sensor can detect kinds of gases,for example,if test gas is water vapor,it has obvious absorption peaks in THz band,and the sensitivities of gas sensor are 64%and 73%at 1.097 THz and 0.752 THz,*** to the ultra-low loss and high sensitivity of the model,the novel steering-wheel structured fiber is very suitable for evanescent-field sensing and the detection of chemical and biological products.

摘要：MCrAlY(M=Ni,Co,NiCo)alloys have been widely used as a bond layer for thermal barrier coatings(TBCs).However;oxides form discontinuously on MCrAlY surface in the marine environment since Cr_(2)O_(3)can react with NaCl and H_(2)O at temperatures above 500℃.Replacing Cr with other alloying elements(such as Si)might prevent severe salt-spray corrosion *** save time and efforts in materials design of the Ni-Si-Al-Y system;we obtained the thermodynamic descriptions of the ternary compounds by coupling the CALPHAD(CALculation of PHAse Diagrams)approach and first-principles *** and eighteen ternary compounds were evaluated and calculated in the Al-Si-Y and Ni-Si-Y systems;*** diagrams of the two systems were depicted after a series of experimental Al/Ni-Si-RE(RE denotes rare earth elements,including La,Ce,Pr,Nd,Sm,Gd,Dy,Ho,and Er)systems being *** is found that the RE elements with the same reference states tend to form ternary compounds with the same crystal *** model-based descriptions are the basis for the research and development of novel NiSiAlY alloys in resisting high-temperature corrosion.

摘要：The design of an ultra-compact SOI-based 1×2 3 dB multimode interference(MMI) coupler is *** symmetric multimode interference structure and deeply-etched parabolically tapered multimode waveguide are used in the *** length of the device is reduced by about 87% compared with general multimode interference straight *** on effective index method(EIM) and two dimensional beam propagation method(2D-BPM),the structure parameters are optimized and the fabrication tolerances are *** results indicate that the performance of the coupler is deeply affected by the coupler's width,etching depth and photolithography alignment error in perpendicular direction.

摘要：The NiSiAlY material is a promising candidate to replace NiCrAlY,which can withstand the harsh saltspray conditions in marine *** efficiently design novel NiSiAlY alloys,this work establishes a thermodynamic dataset of the Al-Ni-Si-Y quaternary system using the CALPHAD(CALculation of PHAse Diagrams)*** employ this database to calculate and predict the phase constitutions and solidification behaviors of different NiSiAlY alloys concerning the content variations of Al and *** have further proposed the selection of the NiSiAlY alloys for serving in marine salt-spray environment with three constraints:(i)outstanding mechanical property;(ii)good high-temperature anti-oxidation;(iii)excellent corrosion *** results in a compositional range of the NiSiAlY alloys with 1 wt%<w(Si)<5 wt%,11 wt%<w(Al)<20 wt%and w(Y)=1 wt%,which corresponds the L1_(2)+bcc B2+Ni_(5)Y ternary phase region at temperatures ranging from~500 to~1000℃.Our predictions are validated by key experiments,suggesting that the model-based description of the Al-Ni-Si-Y system can serve as a guidance to design the novel NiSiAlY alloys in resisting harsh salt-spray environment.

摘要：A multi-channel free space optical interconnection component, fiber optic rotary joint, was designed using a Dove prism. When the Dove prism is rotated an angle of at around the longitudinal axis, the image rotates an angle of 2 at. The optical interconnection component consists of the signal transmission system, Dove prim and driving mechanism. The planetary gears are used to achieve the speed ratio of 2：l between the total optical interconnection component and the Dove prism. The Clenses are employed to couple different optical signals in the signal transmission system. The coupling loss between the receiving fiber of stationary part and the transmitting fiber of rotary part is measured.

摘要：We propose a novel non-contact rotational sensor based on a fiber Bragg grating(FBG) packaged in a core of a magnetic head, which converts the introduced strain from the circular magnetic railings ruler into the rotational information. A mathematical model is built for processing the data obtained by an interrogator, and the accuracy and resolution of the measurements are analyzed by altering the radius and period of the circular magnetic railings ruler, as well as the dimension of the sensor. The experimental results show that it is in good accordance with the theoretical analysis on rotational angle, and the fitting results indicate that the results obtained from the rotational sensor match very well with the real rotational velocity with a linearity of 0.998 and a standard error of about 0.01.

摘要：A C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler is proposed. The mode-evolution structure is designed in a bi-level taper through which the TM;mode can evolve into the TE;mode. Then the TE;mode is coupled to the TE;mode at the cross port using the asymmetric directional coupler. The input TE;mode propagates along the waveguide without mode conversion and output at the through port. From the experimental results, the extinction ratio is lower than 30 dB and the excess loss is less than 1 dB for input TE;mode at the whole C-band. For input TM;mode, the ER and the EL are, respectively,lower than-10 and 1.5 dB.

摘要：The orbitofrontal cortex(OFC)is involved in diverse brain functions via its extensive projections to multiple target *** is a growing understanding of the overall outputs of the OFC at the population level,but reports of the projection patterns of individual OFC neurons across different cortical layers remain ***,by combining neuronal sparse and bright labeling with a whole-brain florescence imaging system(fMOST),we obtained an uninterrupted three-dimensional whole-brain dataset and achieved the full morphological reconstruction of 25 OFC pyramidal *** compared the wholebrain projection targets of these individual OFC neurons in different cortical layers as well as in the same cortical *** found cortical layer-dependent projections characterized by divergent patterns for information *** study not only provides a structural basis for understanding the principles of laminar organizations in the OFC,but also provides clues for future functional and behavioral studies on OFC pyramidal neurons.

摘要：A 25-channel 200 GHz arrayed waveguide grating （AWG） based on Si nanowire wavegnides is designed, simulated and fab- ricated. Transfer function method is used in the simulation and error analysis of AWG with width fluctuations. The 25-channel 200 GHz AWG exhibits central channel insertion loss of 6.7 dB, crosstalk of-13 dB, and central wavelength of 1 560.55 nm. The error analysis can explain the experimental results of 25-channel 200 GHz AWG well. By using deep ul- traviolet lithography （DUV） and inductively coupled plasma etching （ICP） technologies, the devices are fabricated on sili- con-on-insulator （SOI） substrate.