Tolerance analysis for incident angle of volume phase holographic grating used in optical channel performance monitor

Transmission Volume Phase Holographic Grating (VPHG) is adopted as spectral element in the real-time Optical Channel Performance Monitor (OCPM), which is in dire need in the Dense Wavelength -division-multiplexing(DATDM) system. And the tolerance of incident angle, which can be fully determined by two angles: 6 and (p, is finally inferred in this paper. Commonly, the default setting is that the incident plane is perpendicular to the fringes when the incident angle is mentioned. Now the situation out of the vertical is discussed. By combining the theoretic analysis of VPHG with its use in OCPM and changing 6 and (0 precisely in the computation and experiment, the two physical quantities which can fully specify the performance of VPHG the diffraction efficiency and the resolution, are analyzed. The results show that the diffraction efficiency varies greatly with the change of 6 or (p. But from the view of the whole C-band, only the peak diffraction efficiency drifts to another wavelength. As for the resolution, it deteriorates more rapidly than diffraction efficiency with the change of (p, while more slowly with the change of theta. Only if \phi\less than or equal to+/-1degrees and alpha(B) -0.5 less than or equal to theta less than or equal to alpha(B) + 0.5, the performance of the VPHG would be good enough to be used in OCPM system.

16-channel 0.35 mu m CMOS/VCSEL optoelectronic devices

We report some investigations on vertical cavity surface emitting laser (VCSEL) arrays and VCSEL based optoelectronic smart photonic multiple chip modules (MCM), consisting of 1 x 16 vertical cavity surface emitting laser array and 16-channel lasers driver 0.35 mum CMOS circuit. The hybrid integrated multiple chip modules based on VCSEL operate at more than 2GHz in -3dB frequency bandwidth.

16-channel VCSEL based multiple chip modules

　

Two-dimensional numerical simulation of the channel electron in an In0.52Al0.48As/In0.53Ga0.48As HEMT

A two-dimensional quantum model based on the solution of Schrodinger and Poisson equations is first presented for In0.52Al0.48As/In0.53Ga0.47As/InP HEMT. According to the model, the two-dimensional distributions of electron density and transverse electric field in the channel of InAlAs/InGaAs HEMT are discussed.

Origin of flat-band voltage sharp roll-off in metal gate/high-k/ultrathin- SiO2/Si p-channel metal-oxide-semiconductor stacks

The origin of the flat band voltage roll-off (V-FB roll-off) in metal gate/high-k/ultrathin-SiO2/Si metal-oxide-semiconductor stacks is analyzed and a model describing the role of the dipoles at the SiO2/Si interface on the V-FB sharp roll-off is proposed. The V-FB sharp roll-off appears when the thickness of the SiO2 interlayer diminishes to below the oxygen diffusion depth. The results derived using our model agree well with experimental data and provide insights to the mechanism of the V-FB sharp roll-off.

Entrance-channel dependence of isospin effects on double n/p ratio in HIC

Within the hadronic transport model IBUU04, we investigate the effect of density-dependent symmetry energy on double neutron/proton (n/p) ratio of free nucleons in heavy ion collisions by taking four isotopic Sn+Sn reaction systems. Especially the entrance-channel asymmetry and impact-parameter dependence of the effect of symmetry energy are discussed. It is found that in both central and semi-central collisions the sensitivity of the double n/p ratio to the density-dependent symmetry energy is more pronounced in neutron-richer systems. Our results also indicate clearly that the effect of symmetry energy is stronger in central collisions than that in semi-central collisions.

Effect of entrance-channel asymmetry on the isospin dependence of nucleon emission in heavy ion collisions

Using the isospin- and momentum-dependent hadronic transport model 1BUU04, we have investigated the influence of the entrance-channel isospin asymmetry on the sensitivity of the pre-equilibrium neutron/proton ratio to symmetry energy in central heavy-ion collisions induced by high-energy radioactive beams. Our analysis and discussion are based on the dynamical simulations of the three isotopic reaction Systems Sn-132+Sn-124, Sn-124+Sn-112 and Sn-112+(112)Su which are of the same total proton number but, different isospin asymmetry. We find that, the kinetic-energy distributions of the pre-equilibrium neutron/proton ratio are quite sensitive to the density-dependence of symmetry energy at incident beam energy E/A = 400 MeV, and the sensitivity increases as the isospin asymmetry of the reaction system increases.

Entrance channel dependence of the correlation function of IMFs in Ar-36+Sn-112,Sn-124 at 35MeV/u

The reduced velocity correlation functions of the Intermediate Mass Fragments (IMFs) were measured in the reactions of Ar-36+ Sn-112,Sn-124 at 35MeV/u. The anti-correlation at small reduced velocities is more pronounced in Ar-36+ Sn-124 system than that in Ar-36+ Sn-112 system. The difference of the correlation functions between the two reactions is mainly contributed by the particle pairs with high momenta. A three-body Coulomb repulsive trajectory code (MENEKA) is employed to calculate the emission time scale of IMFs for-the both systems. The time scale is 150fm/c in the Ar-36+ Sn-112 system and 120fm/c in the Ar-36+ Sn-124 system, respectively. A calculation based on an Isospin dependence Quantum Molecular Dynamics code (IQMD) reveals that the emission time spectrum of IMFs is shifted slightly leftwards in Ar-36+ Sn-124 compared with that in the Ar-16+ Sn-112 system, indicating a shorter emission time scale. Correspondingly, the central density of the hot nuclei decreases faster in Ar-36+ Sn-124 than in Ar-36+ Sn-112

Entrance channel effects on the role of isospin-dependent momentum interaction in isospin fractionation in heavy ion collisions

An isospin degree of freedom is inserted into the momentum dependent interaction in the quantum molecular dynamics model to obtain an isospin dependent momentum interaction given in a form practically usable in isospin dependent quantum molecular dynamics model. We investigate the entrance channel effects for the role of isospin momentum dependent interaction on the isospin fractionation ratio and its dynamical mechanism in the intermediate energy heavy ion collisions. It is found that the isospin dependent momentum interaction induces a significant reduction of isospin fractionation ratio under all entrance channel conditions. However the strong dependence of isospin fractionation ratio on the symmetry potential is preserved after considering the isospin degree of freedom in the momentum dependent interaction.

新型多道高精度的时间-电压转换电路系统的设计；A Design of New Multi-channel High Precision Time-to-amplitude Convert (TAC) Circuit

在发展髙性能多路小型化前端电路方面,阐述了一种用于测试时间的系统电路的设计与实现。其突出特点是转换速度快,电路结构简单,输入信号范围大、精度高、功耗低,电路采用改进的TAC方法,用于处理快速的时间信号,利用高速DMOS开关,并优化控制逻辑时序,极大提高了测试精度。

Development of multi-channel gated integrator and PXI-DAQ system for nuclear detector arrays

A multi-channel gated integrator and PXI based data acquisition system have been developed for nuclear detector arrays with hundreds of detector units. The multi-channel gated integrator can be controlled by a programmable Cl controller. The PXI-DAQ system consists of NI PXI-1033 chassis with several PXI-DAQ cards. The system software has a user-friendly GUI which is written in C language using LabWindows/CVI under Windows XP operating system. The performance of the PXI-DAQ system is very reliable and capable of handling event rate up to 40 kHz. (C) 2010 Elsevier B.V. All rights reserved.