Study on Generation oand Control of ultrashort Optical Pulses by Electrooptic Modulation.

本研究致力于发展具有高度可控性的电光超短光脉冲产生方法。主要研究成果如下：1)设计并改进了一种基于周期域反转的高调制指数电光相位调制器/偏转器，研制成功了小尺寸波导型准速度匹配周期域反转电光调制器。2)提出了一种新型的基于透镜调制的QVM光相位调制器，并将其应用于无基座飞秒光脉冲电光啁啾压缩方法中。因此，存在这样一个问题：虽然利用群延迟色散的啁啾压缩方法从其中一个啁啾部分获得了短光脉冲，但其他啁啾部分仍然作为背景光存在。我们的新型调制器除了具有相位调制功能外，还具有透镜调制功能。由于调制光束在上啁啾和下啁啾情况下分别聚焦到不同的点，因此我们可以很容易地通过针孔来消除不需要的啁啾部分。利用该调制器，我们成功地利用连续Ar激光器产生了520fs的无基座脉冲。3)提出并设计了用于产生飞秒脉冲的新型法布里-珀罗电光调制器。(日本专利申请待定，H10-258293，CLEG‘99待提交)。

This study has been pursued to develop electro-optical ultrashort optical pulse generation method with high controllability. A main results obtained are as follows ;1) Design and improvement of an electrooptic phase modulator/deflector with high-modulation index using periodic domain inversion scheme.We succeeded in development of compact size waveguide-type quasi-velocity-matching electrooptic modulator with periodic domain inversion. Highly-efficient phase modulation as compared with a bulk-type one has been experimentally confirmed.2) Proposal of a novel QVM optical phase-modulator featuring lens modulation and its application to the electrooptic chirping compression method for pedestal free femtosecond optical pulse generation.Ordinary sinusoidal phase modulation generates both types of the frequency chirping ; up-chirping and down chirping. There was, therefore, a problem that although short optical pulses are obtained from one of chirping part by chirping compression method with the group delay dispersion, other chirping part still remains as background light. Our new modulator has lens modulation function as well as phase modulation function. Since modulated light beam is focused into the different point for the case of up-chirping and down-chirping, respectively, we can easily eliminate the undesirable chirping part by a pinhole. Using this modulator we succeeded in generation of pedestal free 520fs pulses from a cw Ar laser.3) Proposal and design of novel Fabry-Perot electrooptic modulator accompanied with lens modulation for femtosecond pulse generation. (Jpn Patent pending, H10-258293, CLEG '99 to be presented).