塑料复制光栅研究

本文介绍塑料溶液流延技术复制光栅,用于灯具、电扇、舞台等,成本廉价、工艺简便、适于批量生产,为全息光栅在民用领域中推广具有广泛应用价值。     

激光产生蒸汽羽的干涉研究

 根据拍摄1.06 μm长脉冲钕玻璃激光与LY12铝靶耦合产生蒸汽羽的干涉分幅照片，测出在t<50 μs空气冲击波速度约为473 m/s而蒸汽羽阵面扩散速度约为162 m/s。运用蒸汽羽等离子体的有关热力学特性方程组，得到蒸汽羽等离子体的电子密度、电子温度、电离度和吸收系数的最大值分别为N_e≈3.1×10¹⁷ cm^-1，T≈6 096 K，η≈0.014，α_(1.06μm)≈0.03 cm^-1的结果。     

高压合成立方氮化硼的振动光谱

 本文利用FT-IR和Raman光谱对用不同触媒高压合成的不同颜色立方氮化硼晶格振动的声子吸收和散射进行了研究。获得了较完整的晶格振动信息，并在1 000~1 300 cm^-1范围内，观测到了3个新的振动谱带，其中一个位于1 089 cm^-1， 归属为体TO声子和表面TO声子组合带，另两条513、801 cm^-1推测为杂质诱发吸收带。     

冲击波后温度测量的理论问题

 本文讨论了冲击波后温度弛豫的理论方法。和R. Grover及P.A. Urtiew不同，采用了非傅里叶热传导理论，结果和实验十分符合，而实验结果用傅里叶热传导理论是无法解释的。当时间趋于无穷时，这两种方法的结果又趋于一致，文章中作了物理原因的解释。     

保偏光纤偏振器

利用保偏光纤的弯曲损耗特性绕制而成的光纤偏振器已有过报道。但文献[1]中报道的偏振器尺寸太大(φ=100mm),不利于光纤陀螺的小型化。本文介绍一种采用“熊猫”型光纤制成的偏振器,其尺寸较小(φ=30mm),消光比可达到33dB。     

微通道板固定图案噪声及测试研究

叙述微通道板的噪声,着重介绍微通道板固定图案噪声及其简便新颖而又实用的一种测试方法,给出测试结果并进行分析。     

Investigation on an ultra-compact 1\times 2 polymer electro-optic switch using cross-coupling 2N+1 vertical-turning serial-coupled microrings

Generic model and thorough investigation are proposed for a novel $1\times 2$ 1 × 2 polymer electro-optic (EO) switch based on one-group $2N+1$ 2 N + 1 vertical-turning serial-coupled microrings. For realizing boxlike flat spectrum as well as low crosstalk and insertion loss, resonance order and coupling gaps are optimized. The MRR switches with $N \ge 1$ N ≥ 1 reveal favorable boxlike spectrum as when compared with the simple device with only one microring ( $N = 0$ N = 0 ). For obtaining $<-30\,\text{ dB }$ < - 30 dB crosstalk under through-state, the dependency of switching voltage on $N$ N is determined as $7.19 \times \text{ exp }(-N/0.72) + 1.72\,(\text{ V })$ 7.19 × exp ( - N / 0.72 ) + 1.72 ( V ) . Under the operation voltages of 0 V (drop state) and the predicted switching voltages (through state), the device performances are analyzed, and $1 \le N \le 10$ 1 ≤ N ≤ 10 is required for dropping the insertion loss (drop state) below 10 dB. The crosstalk of the ten devices ( $N = 1-10$ N = 1 - 10 ) are $< -19.5\,\text{ dB }$ < - 19.5 dB under drop state and $< -28.7\,\text{ dB }$ < - 28.7 dB under through state, and the insertion losses of the devices ( $N = 1-10$ N = 1 - 10 ) are $< 9.715\,\text{ dB }$ < 9.715 dB under drop state and $< 1.573\,\text{ dB }$ < 1.573 dB under through state. The device also has ultra-compact footprint size of only 0.33–1.06 mm, which is only 1/10–1/3 of those of our previously reported polymer EO switches based on directional coupler or Mach–Zehnder interferometer structures. Therefore, the proposed device is capable of highly integration onto optical networks-on-chip.     

Theoretical and experimental study of single mode-locking pulse generation with low repetition rate in a dual-loss-modulated QML YVO4/Nd:YVO4 laser with EO and GaAs

Using electro-optic (EO) modulator and GaAs saturable absorber, a diode-pumped doubly Q-switched and mode-locked (QML) YVO₄/Nd:YVO₄ laser at 1.06 μm is realized. The experimental results show that the number of the mode-locking pulses underneath the Q-switched envelope decreased with increasing pump power. With an output coupling of 6.5 %, the single mode-locking pulse underneath the Q-switched envelope with 1 kHz repetition rate was obtained when the pump power exceeded 4.65 W. At a pump power of 8.25 W for an output coupling of 10 %, a stable mode-locking pulse train at a repetition rate of 1 kHz was achieved with pulse energy as high as 582 μJ and pulse duration of about 580 ps, corresponding to a peak power of 1 MW. Using a hyperbolic secant square function and considering the Gaussian distribution of the intracavity photon density, the coupled rate equations for diode-pumped doubly QML YVO₄/Nd:YVO₄ laser are given and the numerical solutions of the equations are basically in accordance with the experimental results.     

Nanoscale gap filling for phase change material by pulsed deposition and inductively coupled plasma etching

The gap filling of phase change material has become a critical module in the fabrication process of phase change random access memory (PCRAM) as the device continues to scale down to 45 nm and below. However, conventional physical vapor deposition process cannot meet the nanoscale gap fill requirement anymore. In this study, we found that the pulsed deposition followed by inductively coupled plasma etching process showed distinctly better gap filling capability and scalability than single-step deposition process. The gap filling mechanism of the deposit–etch–deposit (DED) process was briefly discussed. The film redeposition during etching step was the key ingredient of gap filling improvement. We achieved void free gap filling of phase change material on the 30 nm via with aspect ratio of 1:1 by two-cycle DED process. The results provided a rather comprehensive insight into the mechanism of DED process and proposed a potential gap filling solution for 45 nm and below technology nodes for PCRAM.     

激光能量叠加过程中对准精度对焦斑的影响

利用多光束激光输出耦合叠加是一种提高激光器输出功率的有效方法。采用两束矩形激光对准系统,分析两光束不同对准情况下的焦斑特性。完全对准的情况下,两束光的远场焦斑重合在一起,焦斑能量是两光束能量之和。在实际光束对准系统中,讨论了三种常见的对准误差,并比较了这些误差对焦斑特性的影响。利用ZEMAX软件对设计系统进行了模拟分析,并进行了实验验证。结果表明,元件的位置误差会使远场焦斑能量集中度降低,焦斑半径增大。