Generation of Ultrabroad Optical Sideband by Domain-Inversed Waveguide-Type Electro-Optic Modulators and Applications

本研究的目的是开发新型的电光调制器，结合畴反转结构和波导结构，产生超宽的光学边带，并探索其新的应用。在此基础上，我们成功地实现了波分复用（WDM）系统中非常有用的频率梳发生器、移频器、单边带（SSB）调制器和紧凑型集成飞秒光脉冲发生器，并采用波导结构，使驱动功率的大幅度降低成为可能。畴反转结构的几何空间修改使得调制器的多路并行操作或各种类型的空间光调制成为可能。首先，设计了用于超宽带边带产生、频率梳产生和光源应用的电极和光波导的长度和宽度 ...更多信息 在WDM系统中，这需要高的调制效率。结果，有效的连续波调制和宽连续波光边带的产生成为可能。畴反转区的位置偏移等效于调制射频信号的相移，因此，我们可以用单个射频信号实现正弦和余弦调制。利用这种效应，我们构造了一种具有简单波导结构的新型单边带调制器，并成功地证实了它的单边带工作，用通常的相位调制方法得到的边带具有类似贝塞尔函数的幅度，但缺乏平坦性。这是频率梳发生器的问题。我们提出了一种新的空间调制器--平坦分布的空间分离边带发生器，它是通过对倾斜周期畴反转结构产生的行波相位光栅施加空间变形而构成的。此外，我们还成功地采用非周期畴反转结构构成了超宽带调制器。该器件的调制带宽（-1dB）估计比普通行波电光调制器宽6倍。此外，我们还将产生超宽带边带的相位调制器和群延迟色散电路集成在一个钽酸锂针尖上。在初步的实验中，我们成功地利用这种集成器件实现了连续光波到皮秒脉冲的直接转换。少

The purpose of this study is to develop new kinds of electro-optical modulators together with domain inverted structure and wave-guide structure and to generate ultra-broad optical sideband and to find out new application of them. As results, we succeeded in materialization of the frequency comb generator which is very useful as light sources in the wavelength division multiplexing (WDM) system, of the frequency shifter, a single sideband (SSB) modulator and the compact integrated femtosecond optical pulse generators.Adopting the waveguide structure makes it possible to decrease driving electric power drastically. The geometrical spatial modification of the domain-inverted structure makes multipath parallel operation of the modulator or various types of spatial light modulation possible.First of all, the length and the width of the electrode and the optical waveguide were devised for the ultra-broad sideband generation, the frequency comb generator, and application to the light source … More in the WDM system, which require high modulation efficiency. As a result, efficient cw modulation and generation of broad cw optical sidebands became possible. The position shift of domain inverted area yields equivalently the phase shift of modulation rf signals, therefore, we can get sin and cos modulation by single rf signal. Using this effect, we constructed new kind of SSB modulator with simple wave-guide structure and succeeded in confirmation of its SSB operation.The sidebands obtained by a usual phase modulation have Bessel function-like amplitude and lack in flatness. It is problem for frequency comb generator. We proposed the new spatial modulator, spatially separated sideband generator with flat distribution, which is constructed by adding the spatial deform to traveling phase grating produced by tilted periodic domain inverted structure. Moreover, we succeed in the composition of the ultra-broadband modulator by adopting the non-periodical domain inverted structure. The modulation bandwidth (-1 dB) of this device was estimated to be six times wider than that of the normal traveling-wave EO modulator. In addition, we integrated the phase modulator for the ultra-broad sideband generation and the group delay dispersion circuit on one LiTaO_3 tip. In preliminary experiment using this integrated device we succeeded in direct conversion from the continuous light-wave into the picosecond pulses. Less