【作者】 于丹；

【导师】 侯延冰；

【作者基本信息】 北京交通大学 ， 光学， 2009， 硕士

【摘要】 有机聚合物激光是近年来有机发光领域引人注目的研究方向。由于有机聚合物具有荧光量子效率高、受激发射截面大、发光波长可调、制备工艺简单等优点,是理想的激光增益介质材料。本论文主要研究内容是非对称波导分布反馈(DFB)结构聚合物的受激辐射特性,在以下方面开展了创新研究工作。通过在光栅结构衬底上旋转涂覆MEH-PPV的二甲苯溶液制备出非对称光波导,以此为增益介质,在光泵浦条件下实现了红光波段的DFB聚合物受激发射。当泵浦光强增强时,从样品边缘发射的光谱发生增益窄化并具有明显的阈值特性。测得非对称波导DFB结构MEH-PPV薄膜的最低闽值为0.47uJ/pulse。与波导结构的MEH-PPV薄膜的放大的白发辐射(ASE)阈值2.2uJ/pulse相比,非对称波导DFB结构的样品具有明显较低的阈值。这种现象是由DFB的反馈作用和波导效应引起的。研究了不同光栅常数对非对称波导DFB结构MEH-PPV薄膜受激辐射特性的影响,发现随着光栅常数的增加,MEH-PPV薄膜的受激发射峰位置无明显变化,激射阈值在误差允许的范围内基本相同,而增益系数则有所增强。这是由于使用的光栅常数与光波长不可比拟。最后,研究了电场处理MEH-PPV薄膜对DFB结构MEH-PPV薄膜的受激辐射的影响。研究显示所加的电场强度越大,样品的净增益系数越高。这可能是由于电场作用下聚合物分子产生了取向或纳米域相的形成受到禁戒。更多还原

【Abstract】 Conjugated polymers are attractive laser gain media materials due to their high phototuminescence quantum efficiencies,large stimulated emission cross section,chemically tunable emission wavelength and low fabrication cost.In this thesis, the work is concentrated on the study of the stimulated emission characteristics in MEH-PPV film which have an asymmetric waveguide DFB structure,some innovative research in the following aspects is also carried out.An asymmetric waveguide is fabricated by spin coating a thin film of MEH-PPV of xylene solution onto a DFB grating substrate and then works as gain medium. Stimulated emission in red wavelength region can be achieved under photo-pump.The spectra detected from the edge of the sample shows a gain narrowing and a clear threshold when increasing the pump intensity.The minimum threshold of MEH-PPV film with DFB structure is 0.47uJ/pulse.Compared to the MEH-PPV film with a planar waveguide structure whose threshold is about 2.2uJ/pulse,the MEH-PPV film with DFB structure has a notably low threshold.The phenomenon can be attributed to the grating structure and waveguide effects.When altering the grating constants,the spectral locations of the emission peak and the threshold have no significant change. With increasing the grating constants,the gain increases.That is because the grating constants are magnitude large than the optical wavelength.In addition,the influence of electric field treatment on stimulated emission is also investigated.When the electric field intensity increases,the gain of the MEH-PPV film increases rapidly.It may be the result of orientation of polymer molecules or the elimination of forming the nano-domine phase under the presence of an electric field.更多还原