Basic research for realization of an unidirectional optical amplifier

目前还没有发明出能够对信号进行单向放大和传输的有源器件。本研究的主题是利用真空环境中发射的电子束实现单向光放大，由于光波导具有折射率，光在介质波导中的传播速度比在自由空间中的传播速度要慢。通过介质波导传播的光部分地穿透到环境空间。当电子束沿着光波导面辐射，且电子束的速度与光的传播速度一致时，电子束的能量就可以传递给光。也就是说，光学光被电子束放大。传播方向相反的光学光的其他分量永远不会被放大，因为传播速度极快。放大光学光的另一个条件是光应该具有…更像是辐射电子束方向上的电子元件。然后，可以放大光的TM分量。以上就是我们所提出的单向光放大器的工作原理，在得到资金支持之前，我们已经搭建了一个基于真空系统的实验装置。我们在2000年利用这一资金支持购买了电子透镜，以使电子束更强地聚焦。我们还对介质波导的结构进行了改进，通过在波导表面加电极来释放带电电子，直到输出光的测量变得非常不稳定。结果，我们观察到了以蒸发a-Si薄膜为芯层的光波导中导光的增强。我们预计这种增强应该是我们提出的放大现象，因为TM分量随电子束加速电压变化的特性与我们的理论计算很好地吻合。然而，我们仍在调查这些特性的细节，因为TE组件在实验中也得到了增强。这种意想不到的现象可能是由介质材料本身的光吸收和发射引起的。我们还开始了实验，将SOI衬底作为光波导，并制作了用于放大器输入端口的光波导。然而，我们还没有关于这些高级实验的合适数据。较少

Any active device which can amplify and transfer the signal in single direction has not been invented yet. Subject of this research was to realize a unidirectional optical amplifier by utilizing an electron beam which is emitted in vacuum environment.The propagation speed of the optical light in an dielectric wave-guide is slower than that in the free space, because the optical wave-guide has the refractive index. The optical light propagating by the dielectric wave-guide partly penetrates into the environmental space. When an electron beam is radiated along surface of the wave-guide and whose velocity coincides with the propagating speed of the optical light, energy of the electron beam can transfer to the optical light. That is, the optical light is amplified by the electron beam. Other component of the optical light which propagates counter direction is never amplified because the propagation speed is extremely. Another condition to amplify the optical light is the light should has … More an electric component in the direction of the radiated electron beam. Then the TM components of the light can be amplified. Mentioned above is the mechanism of our proposed unidirectional optical amplifier.We had already being constructed an experimental set basing on a vacuum system toward this subject before this financial support was supported. We purchased an electron lens in 2000 by this financial support to make stronger focusing of the electron beam. We also improved structure of the dielectric wave-guide by attaching electrodes to release charged electron on surface of the wave-guide, until when measuring of the output light had been so much unstable. As the result, we observed enhancing of the guided optical light in wave-guide whose core layer wa made with evaporated a-Si film. We are expecting this enhancing should be the phenomenon which we has proposing as the amplification because characteristics of TM components for varying the acceleration voltage of the electron beam is well coincide with our theoretical calculation. However, we are still investigating details of the characteristics, because TE components were also enhanced in experiment. This unexpected phenomena may be caused by optical absorption and emission by the dielectric material itself.We also started the experiment by applying the SOI substrate as the wave-guide and fabrication of a wave-guide for the input port in the amplifier. However, we have not got suitable data on these advanced experiments. Less