可调谐染料掺杂液晶激光器的研究

发布时间：2018-04-28 15:28

  本文选题：手性向列相液晶 + 液晶激光器　； 参考：《沈阳理工大学》2015年硕士论文

【摘要】：液晶激光器是一种将激光染料掺杂到液晶中,并利用光子禁带或多重散射提供光反馈的新型激光器。由于其特殊的结构和激发机制,液晶激光器具有可调谐、窄线宽、激发阈值低和尺寸微小等优点。这些优势使得液晶激光器在光学集成、激光显示、医学和光通讯等领域具有巨大的应用前景。本文从理论模拟和实验两个方面对可调谐液晶激光理论和其产生激光辐射的机理进行了阐述,设计制作了温度调谐负性液晶激光器,电场调谐液晶激光器和染料掺杂聚合物分散液晶激光器。本文采用染料掺杂手性向列相液晶作为增益介质,器件激光辐射机制为光子禁带末端激光(Band-edge Lasing)。论文在光子晶体理论基础上讨论了平面织构态手性向列相液晶结构特点,并利用Berreman’s 4×4矩阵模拟了平面织构态手性向列相液晶器件的透射特性,基于布拉格选择反射理论讨论了其光子禁带特性。采用染料掺杂负性手性向列相液晶设计制作了温度调谐液晶激光器,利用楔形液晶盒测量了其螺距随温度的变化,发现本文使用的负性手性向列相液晶螺距随温度升高而增加。当温度从20℃升高到67℃时,输出波长从614.4 nm红移到662.8nm,器件光子禁带中心波长也随之红移且禁带宽度逐渐变窄。设计了两种电极结构对正性和负性手性向列相液晶激光器分别施加垂直螺旋轴和平行螺旋轴方向的电场。从器件织构、透射谱、激光输出特性等方面分析了液晶激光器件的电场调谐特性,正性和负性液晶激光器分别获得范围约为8nm和18.5nm的电场调谐激光输出。采用微胶囊法制备了聚合物分散液晶薄膜激光器,研究了其激光辐射机制和温度调谐特性。器件中液晶微滴尺寸约为80μm,且微滴中液晶分子呈现平面织构态。以532nm Nd:YAG激光器作为泵浦源,在634.5nm和680.2nm波长处获得了窄线宽激光辐射峰,线宽分别约为0.25nm、0.29nm。升高器件温度其输出激光波长从666.7nm蓝移至643.9nm,共获得22.8nm的调谐激光输出。
[Abstract]:Liquid crystal laser (LCLL) is a new type of laser which is doped with laser dyes and provides optical feedback by photonic bandgap or multiple scattering. Because of its special structure and excitation mechanism, liquid crystal laser has the advantages of tunable, narrow linewidth, low excitation threshold and small size. These advantages make liquid crystal lasers have great application prospects in optical integration, laser display, medicine and optical communication. In this paper, the theory of tunable liquid crystal laser and its mechanism of producing laser radiation are described from the aspects of theoretical simulation and experiment, and the temperature tunable negative liquid crystal laser is designed and fabricated. Electric field tunable liquid crystal laser and dye doped polymer dispersed liquid crystal laser. Dye-doped chiral nematic liquid crystal is used as gain medium. The laser radiation mechanism of the device is Band-edge laser at the end of photonic bandgap. On the basis of photonic crystal theory, the structure characteristics of planar texture chiral nematic liquid crystal are discussed, and the transmission characteristics of planar texture chiral nematic liquid crystal devices are simulated by Berreman's 4 脳 4 matrix. The photonic band gap is discussed based on Bragg selective reflection theory. The temperature tunable liquid crystal laser was fabricated by using dyestuff doped chiral nematic liquid crystal. The pitch of the liquid crystal with temperature was measured by using a wedge liquid crystal cell. It was found that the pitch of the chiral nematic liquid crystal increased with the increase of temperature. When the temperature is raised from 20 鈩，

本文编号：1815848