摘要
利用时域有限差分方法,对非线性光学聚合物SU-8环氧树脂在激光作用下,其折射率会升高的过程进行了数值模拟与分析,得到SU-8薄膜与激光作用一定时间之后,其内部折射率的分布。分别对表面是平面及表面带有微透镜的SU-8薄膜进行了模拟。结果表明,利用折射率升高引起的自聚焦效应,可以在SU-8薄膜内自写入波导;写入的波导以自聚焦焦点为分界点,分为锥形波导和柱形波导。写入的波导长度随着与激光作用时间的增加而增长;在与激光相同的作用时间里,表面带有微透镜的SU-8薄膜,与表面是平面的SU-8薄膜相比,锥形波导的旁瓣更收敛,写入的波导长度更长;在微透镜底面半径保持不变以及曝光时间一定时,微透镜冠高与底面半径比例为0.08时比比例为0.24时写入的波导长度要长12.2%,其中锥形波导部分要长19.2%。
SU-8 epoxy resin is a kind of polymer material of nonlinear optical properties.It is ultraviolet sensitive and its refractive index increases because of the photopolymerization.Finite-difference time-domain method is employed to simulate the process of photopolymerization,and the inner distribution of refractive index of SU-8 film is obtained.Both the process in the plane thin film and the thin film with a microlens are simulated.It is concluded that self-focusing effect which results from the refractive index change leads to the formation of self-written waveguide.The self-written waveguide consists of two continuous parts,one is cone and the other is cylinder.The length of the self-written waveguide increases with the time of exposure.Given the same exposure time,cone part in the SU-8 film with a microlens is more convergent than that without a microlens,and the length of the self-written waveguide in the SU-8 film with a microlens is longer than that without a microlens.The length of the self-written waveguide decreases with the increase of the ratio of the height to the basal diameter,given the same exposure time and a constant basal diameter of the microlens.The length of the self-written waveguide with the ratio 0.08 is 12.2% longer than that with the ratio 0.24,and the cone part with the ratio 0.08 is 19.2% longer than that with the ratio 0.24.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2011年第10期199-204,共6页
Acta Optica Sinica
基金
国家自然科学基金(61072131)
新世纪优秀人才计划(NCET-07-0319)
中央高校基本科研业务费资助(HUST:2010MS069)资助课题
关键词
光学器件
自写入光波导
时域有限差分
自聚焦
SU-8环氧树脂
optical devices
self-written waveguide
finite-difference time-domain
self-focusing
SU-8 epoxy resin
