DMIT类材料三阶非线性光学性能和响应时间的研究

【作者】 杨洪亮；

【导师】 任诠；

【作者基本信息】 山东大学 ， 光学工程， 2006， 博士

【摘要】 我们正处在一个信息社会。人们的社会和经济生活都极大依赖于信息的交流和利用。信息传输量大、传输速率高、响应速度快、抗干扰能力强、信噪比好是信息传输和数据存储等信息领域的发展趋势。光纤通信的出现大大缓解了长期以来一直困扰人们的传输速度低、信噪比差和易干扰等问题。但是在目前的光纤通信系统中，往往存在很多的光电和电光转换器件，而这些电子装置由于存在切换时间慢、时钟偏移、严重串话等缺点，而产生了光纤通信系统中的“信息瓶颈”现象。全关开关是解决这个问题的一个有效手段。全光开关的工作原理利用了材料的三阶非线性光学特性，用一束光引起材料的折射率发生变化，信号光在其中通过时就会带来相位的变化，从而实现光开关的开关动作。由于全光开关可以突破限制电、声、热、机械等光开关单道传输速率的极限，促使人们以极大的热情注目全光开关器件的研究。三阶非线性光学材料还有其它方面的应用，比如制作光限幅器件等。随着飞秒、皮秒等超快激光的出现，光束的光功率密度很容易可达到几百GW／cm~2，在这个强度下，人的眼睛很容易受到伤害，测试用的探测器也很容易被打坏。材料的双光子吸收、反饱和吸收等三阶非线性光学性能都可以用来制作光限幅器件。响应快、防护波段宽、限幅阈值低、透射率高的光限幅器件，能有效防护激光对人眼、传感器以及设备的损害。材料的三阶非线性光学性能还可被应用于调Q、被动锁模等超快激光产生技术方面，飞秒激光脉冲的克尔透镜锁模(Kerr Lens mode locking)技术就是利用了材料的非线性光学特性，因材料的折射率随光强而变化，使得激光器运转中的尖峰脉冲得到的增益高出连续的背景激光增益，从而实现超短激光脉冲的输出。 全光开关、光限幅等器件潜在的多方面实际应用价值，迫使科学家们不断探索、寻求具有高三阶非线性光学性能的新材料。制作全关开关，要求非线性光学材料的三阶非线性折射要大，线性吸收和非线性吸收系数要小，响应速度要快。三阶非线性折射率大，则需要的控制光的光功率密度就不用很高，可降低费用。线性吸收和非线性吸收系数小，可降低信息传输损耗，还可以减小热更多还原

【Abstract】 In the "Information Age", our social and economic life is relying increasing on the cost-effective exchange and use of information. Mass information transmission,high transmission speed, quick response, excellent anti-jamming ability, good Signal-to-Noise are the trends of information field, such as information transmission and data storage. The appearance of optical fiber communications greatly alleviate such problems as low transmission speed, poor Signal-to-Noise and easy disturbance which puzzle people. In modem optical fiber communication systems, there are many optical-electronic-optical converstion apparatus. But these electronical componets have some disadvantages such as stow switching speed, clock displacement and serious crosstalk, which have become the "bottleneck" of optical fiber communication system. Utilizing all optical switches is an effective method to solve the problem. All optical switches use the third-order optical nonlinearity of materials, whose work principle can be described as follows. One laser beam inducing the change of refractive index of materials, signal beam transmitted in mate rials will produce accessional phase change to realizing the "On" or "Off" ofoptical switches. All optical switches can break through the tramsmission speed limits of electro-optical, acousto-optical, thermo-optical and micro electromechanical switches. Such advantages spur people to devote all optical switch research. Third-order optical nonlinear materials have some other applications, such as making optical power limiters. Following the appearance of picosecond and femtosecond lasers, the beam’s optical power density can reach several hundreds of GW/cm~2. Under such intensity, people’s eyes are easy to be hurt and experimental detectors are easy to be damaged. Materials’ two-photon absorption and anti-saturation absorption, etc. can all be used to facture optical power limiters. Optical power limiters having quick response, broad protecting bandwidth, low limiting threshold and high transmission can effectively protect eys, detectors and other devices to be not damaged by lasers. Materials’ third-order optical nonlinearity can be used in Q-switched and passively mode-loked ultrashort laser technology. Femtosecond lasers’ Kerr Lens Mode locking thechnique uses materials’ optical更多还原