一些氧化物和氟化物薄膜材料的折射率

用光谱反射率计测量了下列光学薄膜材料在250～2000毫微米波段的折射率;Ta2O5、HfO2、Y2O3、La2Os、ZrO2、CeO2、CeF3、LaF3,NdF3、MgF2。     

用于高功率激光器的递变折射率增透表面

递变折射率增透表面可在相分离的光学玻璃上形成。这种表面对于1亳微秒、1.06微米的激光脉冲具有12焦耳/厘米2的平均破坏阈值，这个值是薄膜增透涂层破坏阈值的2.5倍。表面的反射率≤0.2%，可以和薄膜增透涂层相比。     

半导体衬底上薄膜折射率的测量

本文用已知折射率的折射液体与半导体衬底上薄膜折射率相匹配的方法测得锗上等离子体阳极氧化膜的折射率为1.66,硅上氧等离子体氧化膜及热氧化SiO_2膜的折射率均为1.458。与激光椭偏仪的测量结果符合得很好。本文还用TP—83型椭偏仪的通用程序B算出砷化镓上等离子体氧化膜的折射率为1.80～1.90。     

用于切割硅薄膜太阳能电池的激光器研究

相比其他加工方式,激光加工具有割线小,切割速度快,割缝边缘垂直度好,切割时无机械应力等优点．本文结合国内外激光薄膜加工研究结果,从激光与物质相互作用的角度出发,建立激光切割硅薄膜太阳能电池的理论模型。用有限元法(FEM)求得柱面坐标下热平衡方程的数值解。讨论激光波长,能量密度,脉冲重复频率,光斑形状与薄膜损伤阈值,切割速度,以及切割质量之间的关系。结合理论分析与实验,优化了激光器的设计,选择氪灯抽运的λ=532nm Nd：YAG激光器,采用KDP倍频,声光调Q方式工作,给了了重复频率与切割速度的配对关系,提了用柱面聚焦系统代替球而聚焦系统,从而减小垂直于割缝方向的热影响,并有利于切割速度的提高。     

用于大功率激光器的薄膜偏振器

用于大功率辐射的最普通的偏振器，是一叠以布儒斯特角放置的板,最近已用薄膜偏振器代替。薄膜偏振器改进了光学装置的实验特性，防护了大功率激光系统，屏蔽了靶反射的辐射。这种偏振器的损耗小,光学孔径大，可非常方便地用于激光束多次通过激活介质的放大系统。     

具有毗邻放大介质的薄膜激光器的受激发射的某些特性

对比研究放大波导层的或者有毗邻放大介质波导的薄膜激光器的受激发射的特性。毗邻放大介质波导激光器的优点是波导和放大介质层的制造工艺上的分离。放大介质是以若丹明6G激活的液体的聚合物薄膜。与激活波导层激光器相对照就发现，有毗邻放大介质波导的激光器发射主要地为高次横模。这两种激光器的泵浦的阈值功率可能不相上下。     

铥激光器腔镜用高损伤阈值氧化物薄膜的研制

2 m波段激光器在环境探测、测风雷达、生物组织切割、光电对抗等领域都有重要的应用价值和前景。而此波段的薄膜通常采用折射率较高的硫化物、砷化物等软膜材料来制备,为了提升该波段薄膜的损伤性能,采用折射率相对较低但能带隙更宽的氧化物材料来制备。利用傅里叶红外光谱仪和弱吸收测试仪分析表征了薄膜中OH基含量的多少和薄膜整体吸收的大小,通过优化工艺,成功制备出了满足2 020 nm的铥(Tm)激光器使用要求的多层介质薄膜。利用微分干涉显微镜观察了经过激光损伤测试薄膜的损伤形貌,结合薄膜中电场分布和应力测试结果,分析探讨了此薄膜的损伤机理,提出进一步优化薄膜损伤特性的方案。     

CoMnNi氧化物非晶薄膜退火研究

用高频溅射法生长CoMnNi氧化物非晶薄膜并进行退火实验.对不同温度退火的样品作X射线分析及电阻测量.结果表明,CoMnNi氧化物非晶薄膜在低于550℃退火,薄膜发生结构弛豫,电阻率升高;550～750℃温区退火,薄膜结构产生晶化.随着退火温度的升高,晶化程度增强,电阻率逐步下降;高于750℃退火,薄膜开始由立方尖晶石向四方尖晶石结构转化,电阻率增大.还给出了老化实验结果.     

射频溅射CoMnNi氧化物薄膜结构研究

按一定原子比的CoMnNi氧化物混合体,经压片、高温烧结,制成具有尖晶石结构的靶.采用射频溅射,分别在单晶硅、玻璃和氧化铝陶瓷衬底上淀积生长的CoMnNi多成份氧化物薄膜,是一种理想的宽温区热敏材料.扫描电镜能谱和俄歇谱分析表明薄膜中Co,Mn,Ni的原子比偏离靶材料的设计值;X射线衍射谱证明这种薄膜具有非晶结构或尖晶石结构.文章给出了退火后X射线衍射谱及傅利叶交换红外光谱和激光喇曼谱,讨论了生成非晶薄膜和尖晶石结构的条件.     

锗薄膜在低温下的折射率研究

利用电子束蒸发方法在双面抛光的ZnSe基底上镀制单层Ge薄膜.在80 K~300 K温度范围内,采用PerkinElmer Frontier傅里叶变换红外光谱仪低温测试系统每20 K测量Ge单层在2~15 μm波长范围的透射率.采用全光谱反演拟合方法得到Ge单层在不同温度下的折射率.结果显示,Ge单层折射率均随波长增大而减小,且变化趋势基本相同.利用Cauchy色散公式对折射率波长色散关系进行拟合,得到Ge薄膜材料折射率温度/波长色散表达式为:n(λ,T)=3.29669+0.00015T+5.96834×10-6T2+0.41698λ2+0.17384λ4.最后,验证了Ge单层膜折射率温度/波长色散公式的准确性.     

Depth profiles of refractive index in thermally grown and LPCVD oxide films on silicon

Thin and thick silicon oxide films are grown by thermal oxidation of silicon in dry oxygen or by LPCVD from a mixture of monosilane with oxygen or nitrous oxide. Depth profiles of refractive index are determined in these films by monochromatic ellipsometry, with the measurements interpreted by solving an inverse problem within a multilayer model. The differences between the depth profiles are found to be consistent with well-known mechanisms of film growth under the process conditions applied.     

Carrier density dependence of refractive index in AlGaAs semiconductor lasers

Carrier density dependence of the refractive index in the active layers of semiconductor lasers is evaluated from the wavelength shift with increases in current by taking into account effects of the active layer temperature rise and lateral carrier and optical field distributions on the wavelength shift. The derived refractive index change due to carrier density increase is-4 times 10^{-27}m³, which is in good agreement with the theoretical value.     

Carrier-induced differential refractive index in GaInAsP-GaInAsseparate confinement multiquantum well lasers

Measurements of subthreshold spectra on SCMQW (separate-confinement multiquantum-well) lasers with the number of wells varying from three to nine have led to the determination of the carrier-induced differential refractive index dμ/dN~-3.6×10^-20. This value is 1.8 greater than in the case of conventional bulk lasers. This study allows for a better understanding of quantum well laser parameters such as the spectral linewidth enhancement factor. It is also useful for the design of tunable lasers     

Dispersion of the group velocity refractive index in GaAs double heterostructure lasers

The dispersion of the refractive index corresponding to the group velocityn*_{1}has been measured as a function of wavelength. It is obtained from the longitudinal mode spacing of GaAs buried heterostructure lasers at threshold. The dependence ofn*_{1}on wavelength contains an approximately constant term due to the refractive index n1and a strongly dispersive component due to-lambda (partialn_{1}/ partiallambda). For a given spectral bandwidth, the dispersion ofn*_{1}causes a temporal broadening of a pulse as it passes through the medium. This dispersive effect is shown to contribute to the width of 0.65 ps long pulses obtained recently from mode locked semiconductor lasers. By reducing the length of the laser, the dispersive effect is reduced and it is suggested that pulses as short as 10^-13s should be obtainable from such mode locked semiconductor lasers.     

Influence of refractive index nonlinearities on modulation and noise properties of semiconductor lasers

The modulation response and the spectral linewidth of singlemode semiconductor lasers are analysed by taking into account the nonlinear gain and the nonlinear refractive index in the rate equations. It is shown that the effect of nonlinear gain and index can be included through an effective linewidth enhancement factor alpha /sub eff/ that is different for frequency modulation and for spectral linewidth. The effect of the nonlinear index is particularly strong in the case of frequency modulation where alpha /sub eff/ can become zero or even negative for lasers operating on the red side of the gain peak. In the case of laser noise, alpha /sub eff/ causes linewidth saturation but no rebroadening at high output powers. The authors' results indicate that gain and index nonlinearities are not the cause of linewidth rebroadening.<>     

An approximate expression for the effective refractive index in symmetric DH lasers

Using a variational method and an approximate equation for the confinement factor, a simple expression for the effective refractive index of the TE0modes in a symmetric double heterostructure (DH) laser is obtained. The relative error is smaller than 1.2 percent. Its applications are discussed.     

Minimal group refractive index dispersion and gain evolution in ultra-broad-band quantum cascade lasers

The group refractive index dispersion in ultra-broad-band quantum cascade (QC) lasers has been determined using Fabry-Perot spectra obtained by operating the lasers in continuous wave mode below threshold. In the wavelength range of 5-8 /spl mu/m, the global change of the group refractive index is as small as +8.2 /spl times/ 10/sup -3/ /spl mu/m/sup -1/. Using the method of Hakki and Paoli (1975), the subthreshold gain of the lasers has furthermore been measured as a function of wavelength and current. At the wavelength of best performance, 7.4 /spl mu/m, a modal gain coefficient of 16 cm/spl middot/kA/sup -1/ at threshold and a waveguide loss of 18 cm/sup -1/ have been estimated. The gain evolution confirms an earlier assumption that cross-absorption restricted laser action to above 6 /spl mu/m wavelength.     

常用激光介质膜的斜入射性能

本文给出了多层介质膜反射率与入射角的关系的计算机程序，并列出了部份常用激光膜片反射率-角度曲线。     

光纤布拉格光栅的折射率传感研究

采用光纤布拉格光栅制备折射率传感器,研究光纤光栅的折射率传感灵敏度与其包层直径之间的关系。理论分析可得,光栅包层直径越小,Bragg波长的偏移量随环境折射率变化的影响越大,这样就能使实验中光栅所反射的LD光功率变化(传感灵敏度)越明显。利用氢氟酸溶液腐蚀光栅包层的方法,得到不同包层直径的光纤Bragg光栅折射率传感器。实验指出,包层直径减小时,光栅可传感的折射率范围会缩小,而其折射率的传感灵敏度却会增大,如包层直径为8.9 μm时,折射率的检测范围为1.3872~1.4730,其最大灵敏度值达到了224.0320 dBm/RIU。     

Technique for forming ITO films with a controlled refractive index

A new method for fabricating transparent conducting coatings based on indium-tin oxide (ITO) with a controlled refractive index is proposed. This method implies the successive deposition of material by electron-beam evaporation and magnetron sputtering. Sputtered coatings with different densities (and, correspondingly, different refractive indices) can be obtained by varying the ratio of the mass fractions of material deposited by different methods. As an example, films with effective refractive indices of 1.2, 1.4, and 1.7 in the wavelength range of 440–460 nm are fabricated. Two-layer ITO coatings with controlled refractive indices of the layers are also formed by the proposed method. Thus, multilayer transparent conducting coatings with desired optical parameters can be produced.