K9玻璃薄膜对离子交换磷酸盐玻璃波导表面保护的优化研究

采用镀K9玻璃薄膜方法来解决离子交换掺铒磷酸盐玻璃波导表面的侵蚀问题,对K9玻璃薄膜的厚度进行了优化研究。测量分析了样品的荧光光谱和荧光寿命,采用光学显微镜和棱镜耦合技术对不同K9玻璃薄膜厚度下制备波导的表面形貌和导光特性进行了表征和测试。结果表明,与掺铒磷酸盐玻璃原材料相比,镀K9玻璃薄膜后荧光光谱保持不变,荧光寿命稍有下降(约0.2 ms);K9玻璃薄膜的厚度在60~80 nm的范围内保护效果最佳。为下一步制备掺铒有源玻璃光波导器件奠定了良好的实验基础。

System error removal and structure optimization based on Fizeau interferometer

In the process of interferometric testing, the measurement result is influenced by the system structure, which reduces the measurement accuracy. To obtain an accurate test result, it is necessary to analyze the test system, and build the relationship between the measurement error and the system parameters. In this paper, the influences of the system elements which include the collimated lens and the standard surface on the interferometric testing are analyzed, the expressions of phase distribution and wavefront error on the detector are obtained, the method to remove some element errors is introduced, and the optimization structure relationships are given. (C) 2006 Elsevier GmbH. All rights reserved.

Smoothing the side lobes of a focused pattern by spectral dispersion in the broadband laser

Starting from the Huygens-Fresnel diffraction integral, the propagation equations of a broadband laser passing through a dispersive lens and a dispersive wedge are derived. Smoothing effect on the side lobes of the focused pattern is achieved as the broadband laser passes through the lens because of the spectral dispersion of the lens. By inserting a dispersive wedge behind the lens, better smoothing effect is realized because a relative position shift between focused patterns of different frequency components is generated due to the spectral dispersion of the wedge. Smoothing effect on the side lobe is obtained even with small bandwidth of the broadband laser as the wedge is used. (c) 2006 Elsevier GmbH. All rights reserved.

Focusing properties of concentric piecewise cylindrical vector beam

The focusing properties of a concentric piecewise cylindrical vector beam is investigated theoretically in this paper. The beam consists of three portions with different and changeable phase retardation and polarization. Numerical simulations show that the evolution of the focal shape is very considerable by changing the radius and polarization rotation angle of each portion of the vector beam. And some interesting focal spots may occur, such as two- or three-peak focus, dark hollow focus, ring focus, and two-ring-peak focus. Corresponding gradient force patterns are also computed, and novel trap patterns, including cup shell shape trap with one trap at its each side along axis, rectangle shell shape trap with one trap at its each side, dumbbell optical trap, spherical shell optical trap, may occur, which shows that the concentric piecewise cylindrical vector beam can be used to construct controllable optical tweezers. (c) 2006 Elsevier GmbH. All rights reserved.