含纳米随机微腔MEH-PPV/玻璃光波导激光

MEH-PPV/Glass Waveguide Laser with Random Nanoparticles Microcavities

用浸涂法制备了ＭＥＨ－ＰＰＶ／ＴｉＯ２重量比分别为１∶０，１∶１，１∶２和１∶３四种不同纳米微晶薄膜。与已报道的亚微米散射体不同，本实验采用粒径约为２０ｎｍ的ＴｉＯ２纳米微晶作为多重散射体。可以不必考虑光在散射体上的出、入射方向和内部传播情况。飞秒激光器经ＯＰＡ调谐产生脉宽为１３０ｆｓ的超短脉冲，激发波长为５４４ｎｍ，重复频率为１ｋＨｚ，激发功率为３μＪ／ｐｕｌｓｅ。研究了不同激发强度下，光谱的增益窄化，激射强度和与激发光条长度的关系。这种激光发射的本质还是放大自发辐射（ＡＳＥ）为主。分析了在平均自由程 ｌ＝５．４ ×１０５ｎｍ下光的输运和光局域对这种随机激光产生的影响。

The four kinds of films MEH-PPV(1mg)/ml, [MEH-PPV(1mg) + TiO2(1mg)]/ml, [MEH- PPV(1mg) + TiO2 (2mg)]/ml and [MEH-PPV( 1mg) + TiO2 (3mg)]/ml were made by dip coating method. The diameters of the scatters TiO2 are of submicrometer in all reports published before in films or solutions. Random lasing with the scatters of 20nm has been reported in this letter. The femtosecond laser through OPA hamornics produce 130fs pulse duration, 544nm exciting wavelength, 1kHz repeat ratio, and 3~μJ/pulse pump power. The spectrum line narrowed dramatically almost in two orders of magnitude, smaller than the spectrum lines excited by Xenon lampe. The outputs on the end of the film were exponen- tially increased with lengthening the excitation stripe of laser beam. It is shown that the amplified sponta- neous emission (ASE) is the dominant mechanism. The effects of Anderson location of light on random las- ing with the mean free path l = 5.4×105nm were discussed.