【作者】 陶卫东；

【导师】 陆祖康；

【作者基本信息】 浙江大学 ， 光学工程， 2005， 博士

【摘要】 近年来,手征介质材料中电磁波传输研究成为国内外一个新的热点。有关研究表明,由于波导中添加的手征介质对波的传播特性产生的影响,类似于各向异性材料的作用结果,其本构关系中电场和磁场是交叉耦合的,在其中能传播具有不同传播速度的左旋和右旋电磁波,因此,手征波导具有许多特有的性质,根据这些效应,完全有可能研制出许多新器件,例如消偏振器、极化仪、双讯器、传感器、新型开关及调制器等。本课题旨在对手性光学波导元件及其材料进行研究。 在实验研究方面,主要完成以下几方面的研究工作: 研制出含手性分子葡萄糖和灰黄霉素的硅基溶胶—凝胶材料,发现无论是在液态的溶胶,还是在固态的凝胶,它们均表现出相似的光学活性。 研制出含手性分子灰黄霉素的PMMA溶胶—凝胶材料,发现也能得到上述类似的光学活性结果。通过傅立叶红外谱进行测试发现,手性分子填充于凝胶基质的介质孔中,而并未与基质成键。 研制出含微米手性晶粒的凝胶玻璃,发现其表现出消偏振的效应。而将微米手性晶粒替换成同样尺寸粒径的玻璃粉体,以同样方法制成的相同厚度的含微米玻璃粉体的凝胶玻璃,却表现出线偏振保持的性能。 采用标准水溶液法生长出各向同性的手性氯酸钠微小品粒,并采用溶胶—凝胶法获得含手性氯酸钠晶粒的凝胶材料,发现氯酸钠可与溶胶—凝胶体系构成有旋光特征的手征材料。首次从实验上证实,在紫外区域,氯酸钠晶体在各个方向上均表现出相同的圆二色性:在可见光区域,氯酸钠晶体在各个方向上均表现出相同的旋光色散特性,这一现象与另外一种手性晶体水晶显然是不同的。 研制出固体手性圆波导,通过对手性圆波导和非手性圆波导的偏振特性进行测试,并与块状手性材料进行比较,发现固体手性圆波导具有特有的光学偏振特性。 为实现上述材料的特性测量,自行试制了一套偏振特性测量装置、一套以超高亮度LED为光源的四波段旋光色散仪以及一套基于光栅光谱仪的旋光色散装置,获得的测量结果具有较高的精度,较好的重复性、稳定性。 在理论研究方面,主要完成以下几方面的研究工作: 研究了纤芯和内外包层都有手征的双包层手征光纤中的半漏模,发现双包层手征光纤中的半漏模特性与单包层手征光纤中的相比有很大不同。当只有包层中有手征时,单包层手征光纤中也存在半漏模。 研究了双包层手征光纤纤芯和内外包层的手征参数及内包层厚度对模式色散特性的影响,发现在双包层光纤的纤芯和内外包层中引入手征,可以极大地改变光纤中基模的色散特性,特别是内包层厚度不同时,色散特性也极为不同。更多还原

【Abstract】 Recently, one could more easily see the ever growing interest into effect of chiral media on electromagnetic waves. Recent publications on guided wave propagation in structures filled with chiral material have shown that the effects which occur are similar to the ones in waveguides containing anisotropic materials. Because the constitutive relations for electric and magnetic fields are coupled in chiral materials, two waves with different propagation speeds can be supported. Based on this effect a number of new constructions including depolarizers, polarimeters, diplexers, sensors, switches,and modulators can be proposed. In this dissertation, the optical chiral waveguide components and chiral materials were studied.In experiment, a series research have been implemented as following:The chiral molecule glucose and griseofulvin were firstly incorporated in sol-gel derived materials containing SiO2. It was discovered that the similar behaviors of optical activity for the chiral molecules in solutions were held in solid gels.Chiral molecules griseofulvin were disseminated in poly methyl metahcrylate (PMMA), the similar resuls were obtained. Their infrared spectrum properties has been measured by Fourier transformation infrared spectrometers. The results showed that the chiral molecules filled into the pores of the network structures in the gel, which hardly linked with the host.Sol-gel glass containing chiral micro-crystal had been manufactured successfully. It was discovered that sol-gel glass containing chiral micro-crystal displayed its depolarization effect. We replaced the chiral micro crystal by glass powder and manufactured the sol-gel glass containing glass powder by the same way. It was discovered that the sol-gel glass containing glass powder displayed its polarization-helding character.Crystals of sodium chlorate were grown from water solution by standard rocking techniques. The transparent chiral material containing Sodium chlorate was successfully manufactured by sol-gel process. It was firstly proven by our experiment that the circular dichroism (CD), UV spectrum and optical rotatory dispersion of crystal NaClO3 were isotropic. They are not as same as those of quartz.A solid chiral circular waveguide had been manufactured successfully. After the experimental investigation of its polarity response, it is found that its polarization state is changed when comparing with the bulk chiral medium and the solid circular waveguide.In order to test the characters of the material above, we fabricated a series apparatus such as devices of testing polarization, optical rotatory dispersion instrument based on LED and spectrum instrument. The results show that they possess high accuracy, good repetition and convenience.In theory, two aspects have been done as follow:The semi-leaky modes in doubly clad chiral optical fibers which the core, inner and outer cladding are chiral media have been investigated. It was discovered that the characteristics of semi-leaky modes in doubly clad chiral optical fibers are very different from those in single clad chiral optical fibers. The semi-leaky modes can also exist in the single clad optical fiber whose core material is achiral and the cladding material is chiral.The effects of chirality and thickness of inner cladding on the modal dispersion had been studied . It was discovered that introduing chirality to the core, inner and outer cladding of an optical fiber can change its modal dispersion characteristics drastically. The dispersion characteristics are very different especially under different thickness of inner cladding.更多还原