激光二极管抽运的国产Yb:YAG陶瓷激光器

研究了国产Yb:YAG陶瓷的激光输出特性。激光器采用激光二极管(LD)纵向同轴抽运Yb:YAG陶瓷样品,样品的掺杂原子数分数为1%,一端面镀940 nm和1030 nm双增透膜,另一端面镀1030 nm增透膜,激光器在1031 nm处获得了近红外激光输出。实验中分别测试了Yb:YAG陶瓷在不同输出透射率(T=4%,8%,10%)条件下的激光输出特性。整个实验过程中,激光器维持基横模运转。当输出透射率为10%,吸收的抽运功率为9 W时,激光器获得最大的激光输出功率为1.63 W,相应的斜率效率为23.2%。

Ultrafast dynamics in ZnO thin films irradiated by femtosecond lasers

The damage morphologies, threshold fluences in ZnO films were studied with femtosecond laser pulses. Time-resolved reflectivity and transmissivity have been measured by the pump-probe technique at different pump fluences and wavelengths. The results indicate that two-phase transition is the dominant damage mechanism, which is similar to that in narrow band gap semiconductors. The estimated energy loss rate of conduction electrons is 1.5 eV/ps. (c) 2005 Elsevier Ltd. All rights reserved.

Tunable focal depth of an apodized focusing optical system

The axial intensity distribution and focal depth of an apoclized focusing optical system are theoretically investigated with two kinds of incident light fields: a uniform-intensity-distribution beam and a Gaussian beam. Both a low-numerical-aperture and a high-numerical-aperture optical system are considered. Numerical results show that the depth of focus can be adjusted by changing the geometrical parameters and transmissivity of the apodizer in the focusing optical system. When a Gaussian beam is employed as the incident beam, the waist width also affects the depth of focus. The tunable range of the focal depth is very considerable. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Tunable focal depth of an apodized focusing optical system

The axial intensity distribution and focal depth of an apoclized focusing optical system are theoretically investigated with two kinds of incident light fields: a uniform-intensity-distribution beam and a Gaussian beam. Both a low-numerical-aperture and a high-numerical-aperture optical system are considered. Numerical results show that the depth of focus can be adjusted by changing the geometrical parameters and transmissivity of the apodizer in the focusing optical system. When a Gaussian beam is employed as the incident beam, the waist width also affects the depth of focus. The tunable range of the focal depth is very considerable. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Optical fiber long-period grating with solgel coating for gas sensor

The novel long-period fiber grating (LPFG) film sensor is composed of the long-period grating coated with solgel-derived sensitive films. The characteristics of the transmissivity of the LPFG film sensor are studied. By analyzing the relation among the sensitivity S-n, the thin film optical parameters, and the fiber grating parameters, the optimal design parameters of the LPFG film sensor are obtained. Data simulation shows that the resolution of the refractive index of this LPFG film sensor is predicted to be 10(-8). Experimentally, a LPFG film sensor for detection Of C2H5OH was fabricated, and a preliminary gas-sensing test was performed. (c) 2006 Optical Society of America.

TeO2-Nb2O5-YF3玻璃系统的形成区及性质研究

制备了一种新型的氧卤碲酸盐玻璃：TeO2-Nb2O5-YF3,给出并研究了TeO2-Nb2O5-YF3三元系统的玻璃形成范围。测试了玻璃的密度、折射率、差热(DTA)、拉曼光谱、红外透射光谱以及紫外吸收光谱,通过光谱分析研究了组分含量的变化对玻璃结构及红外透射特性的影响。实验结果表明,TeO2-Nb2O5-YF3玻璃系统具有优良的成玻璃性能和热稳定性等特性,而且在2.8～3.3 μm区域内无明显的[OH]基团吸收,在中红外3～5 μm区域具有优良透射性能,因此在中红外透射方面具有潜在应用价值。

温梯法生长大尺寸蓝宝石晶体的脱碳去色退火研究

温度梯度法（temperature gradient technique，TGT）生长的Al2O3晶体因石墨发热体在高温时的挥发和原料中过渡性金属离子的存在，在不同部位呈现不同颜色，一般上部为浅红色，尾部为浅黄绿色．将TGT法生长的Al2O3晶体（Ф110×80mm^3）依次经过高温氧化气氛、高温还原气氛脱碳、去色退火实验，即“两步法”退火实验，晶体变成无色、透明．经测试，Al2O3晶体的完整性、光学透过率和光学均匀性均有显著提高.

温梯法蓝宝石（Al2O3）晶体的脱碳去色退火研究

温度梯度法（TGT）生长的Al2O3晶体因石墨发热体在高温时的挥发和原料中过渡性金属离子的存在，晶体在不同部位呈现不同颜色，一般上部为浅红色，尾部为浅黄绿色，将TGT法生长的Al2O3晶体（Ф110×80mm^3）依次经过高温氧化气氛、高温还原气氛脱碳、去色退火实验，即“两步法”退火实验，晶体变成无色、透明，经测试，Al2O3晶体的完整性、光学透过率和光学均匀性均有显著提高。

The correlation between preferred orientation and performance of ITO thin films

The tin-doped indium oxide (ITO) thin films were prepared by reactive thermal evaporation on the glass substrates. The effects of substrate temperatures (T-s) on the grain preferred orientation, the electrical and optical properties of ITO films were studied. X-ray diffraction (XRD) patterns indicated that the preferred orientation of film changes from (222) to (400) as T, > 200 degrees C. It can be explained by that the low-index crystallographic planes are easier to be formed when the adatoms have high surface mobility. The Hall measurements indicated that both the concentration and mobility of carrier increase with increasing T,,,. The grain orientation of film does not influence the transmissivity and the carrier concentration, but enhances the carrier mobility. The transmissivity of ITO films is over 90% in the visible wavelength region (except that of the film deposited at 125 degrees C). A minimum resistivity of 5 X 10-4 Omega cm is achieved for the (400) preferred orientation film. Thus, the highest figure of merit of 3.5 x 10(-2) square/Omega is obtained for the film with (400) preferred orientation. The correlation between the preferred orientation and electrical and optical properties are discussed.

Large and negative lateral displacement in an active dielectric slab configuration

We investigate the large negative lateral displacements of TE polarized light beams reflected from or transmitted through an active slab surrounded by transparent medium. The large negative displacements can be achieved when the incidence angle of the beam is less than but close to the critical angle for total reflection. It is also shown that both the reflectivity and transmissivity of the beam that correspond to the large negative displacements can be enhanced by active medium. These phenomena may lead to convenient measurements and interesting applications in optical devices. (c) 2006 Elsevier B.V. All rights reserved.