Control of the carrier-envelope phases of a synchronously pumped femtosecond optical parametric oscillator and its applications

The intrinsic synchronization, multi-color outputs and related carrier-envelope phases （CEP） among pulses bring advantages to synchronously pumped femtosecond optical parametric oscillators and the pumping sources for broadband frequency comb generation and ultrashort waveform coherent syn-thesis. In this paper, we discuss our latest research results in this field, which cover the following as-pects： the phase relationship and energy conservation law in an OPO and related experimental verifi-cation; control of the pumping Ti-sapphire femtosecond laser＇s CEP by self-referencing technology, and its repetition-rate locking by piezoelectric transducer （PZT）; CEP locking of the pulses from the OPO by beating the non-phase-matched visible outputs against pump supercontinuum to obtain a driving signal for a fast PZT on the OPO end mirror; the generation of a broadband frequency comb spanning from 400 nm to 2.4 μm with 1.2 kHz bandwidth; and the realization of coherent interference between phase controlled pump pulses and signal second harmonic pulses.     

Quantum coherent control of ultrashort laser pulses

The effective photonic control is one of the key issues in photo-physics. Significant advancement in photonic crystals, quantum optics, ultrafast optics as well as micro-nano-optics gives rise to new op-portunities to manipulate the emission and propagation in optical fields, leading to a number of new and interesting discoveries, e.g., ultrashort light pulse storage and efficient energy conversion. This paper reviews the latest research progress in storage, release and energy conversion for ultrashort laser pulses in periodical arrays of absorbing medium. Techniques to fabricate such devices are also presented.     

Signal and reference wave dually encrypted digital holographic system

We propose a secure digital holographic system with signal and reference waves dually encrypted. Two random phase masks are used to encrypt the images in the input and the Fourier planes. The reference beam is phase encoded by another random phase mask. The encrypted image and the key are recorded by a CCD camera. The data can be processed or transferred directly by computer. We theoretically and experimentally demonstrate encryption and decryption of multiple images and the results show a high quality and good fault tolerance.     

Optical nonlinearity and ultrafast dynamics of ion exchanged silver nanoparticles embedded in soda-lime silicate glass

Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subse-quently annealing method. Z-scan technique, femtosecond time-resolved optical Kerr effect （OKE） technique and femtosecond pump-probe experiment were used to investigate the effects of laser wavelength and laser pulse duration as well as annealing temperature on the third-order optical nonlinearity and ultrafast dynamics of the composites. It was found that the third-order susceptibility of Ag nanoparticles composite glass measured by 400 nm pulse source is larger than that measured by 800 nm pulse source due to an enhancement effect of local field near surface plasmon resonance of Ag nanoparticles in silicate glass. The third-order optical nonlinearity measured by ns laser source is about two orders of magnitude larger than that measured from fs pulse. The annealing temperature has an important effect on the third-order optical nonlinearity and ultrafast dynamics of the composites. Third-order nonlinear susceptibility up to 10^-l0 esu and fast relaxation process up to 0.2 ps have been obtained in Ag nanoparticles doped glass.     

谱域光学相干层析成像系统的实验研究

为改善光学相干层析成像(OCT)技术图像的获取速度和灵敏度,搭建了一套基于光谱干涉法的谱域光学相干层析成像系(SD-OCT).该系统采用宽带光源照明,通过光纤迈克尔逊干涉仪产生物体的干涉图形并被光谱仪采集,物体内部结构图像则由干涉图形的傅里叶变换获得.研究表明,SD-OCT的数据获取速度比传统的OCT系统提高了将近40倍,达到了16 000/s的轴向扫描速率,其灵敏度也改善了20～30 dB.因此,SD-OCT可实现工程和生物材料内部结构的实时三维图像重构.     

用DMD光学再现全息图的研究

构建了以电荷耦合器件(CCD)为全息记录设备,数字微反射器（DMD）为光学再现设备的数字全息系统.从计算全息图和CCD记录全息图两个方面研究了用DMD光学再现物光场.实验结果表明两种情况下DMD都能很好地再现出物光场,计算机制全息图的再现像质量要比CCD记录全息图的要好些.对CCD直接记录的全息图进行边缘锐化后,其再现像的对比度增强,再现质量得到显著改善.这些实验结果有利于该技术应用于实时干涉计量等工程领域,具有潜在的实用前景.     

Pr^3＋离子含量对GeS2-Gla2S3-KBr玻璃性能的影响

用熔融淬冷方法制备Pr^3＋掺杂的硫卤玻璃（0．64GeS2-0．16Ga2S3-0．2KBr）1-x -PrCl3）x,x=0,0．001,0．003,0．005．对玻璃进行X射线衍射实验分析、差热分析、红外透射光谱、紫外透射光谱的测试,结果分析表明：Pr^3＋掺杂到0．5mol％,都形成良好的玻璃态;掺杂后玻璃的稳定性降低,玻璃的红外透过率增大,截止边不变;玻璃的紫外截止边向短波方向移动;玻璃在588nm处存在吸收峰,对应着Pr^3＋的^3H4→^1D2跃迁．     

某综合楼加层改造设计

某3层砖混结构办公楼需拆除层1部分承重墙,改造成为大空间的办公室门厅。承重墙顶部的圈梁需加固。由于层3墙体不拆除,层2梁上部荷载较大,采用了圈梁侧做托梁、后拆墙的方案。层2墙拆除后,层2梁上部荷载较小,加固可采用临时硬撑支顶,先拆墙、在梁底加大截面的方案;为支撑托梁,对构造柱进行了处理。     

一种新型的玻璃材料——硼磷酸盐玻璃

硼磷酸盐玻璃是一种新型的玻璃材料.是通过在磷酸盐玻璃系统中加入适量的氧化硼制备的.它具有一系列区别于传统玻璃的物理、化学、光学性能.本文对硼酸盐玻璃系统、硼磷酸盐玻璃的性能和应用做了综述.     

浅谈异形柱框架的设计与构造

本文分析了的特点和结构布置,以及结构计算和截面选择等设计计算问题。