Integrated Optical Wavelength Converters and Parametric Amplifiers in Periodically Poled Lithium Niobate (PPLN)

该项目是清华大学两个中国研究小组(北京，中国)和三个德国研究小组(弗劳恩霍夫电信研究所-海因里希-赫兹研究所、柏林工业大学、帕德伯恩大学)联合研究计划的一部分。它的总体目标是通过波长转换解决光突发交换(OBS)网络中的竞争。该子项目的目标是开发用于使用OBS的光纤波分复用(WDM)通信系统的超高速、调制格式透明、偏振相关和偏振不敏感的集成全光波长转换器和参数放大器。这两种器件分别利用了利用级联二次谐波/差频(CSHG/DFG)和级联和频/差频(cSFG/DFG)的周期极化铌酸锂(PPLN)光波导的高光学非线性。首先是在非线性转换效率和稳定性方面的进一步改进。第二是优化设备的配置，在第一个项目阶段确定为最有希望的配置。这也包括对偏振不敏感的设置。这些设备将作为第三个电信窗口--第三个主题--的(可调谐)全光波长转换器进行操作和表征。在更高的泵浦功率水平下--这是第四个主题--可以实现净光参量放大。它将首先在脉冲工作模式下进行研究。根据光波导特性的不同，还可以实现连续波操作。特定的波长转换器和参数放大器将移交给项目合作伙伴HHI，用于进一步表征和研究高速相位调制光纤传输系统。

This project is part of a joint research programme of two Chinese groups at the Tsinghua- University (Beijing, China) and of three German groups (Fraunhofer-lnstitute for Telecommunications - Heinrich-Hertz-lnstitut, Technical University Berlin, University of Paderborn). Its overall objective is contention resolution in optical burst switching (OBS) networks by wavelength conversion.The objective of this sub-project is the development of ultra fast, modulation format transparent, polarization-dependent and polarization-insensitive, integrated all-optical wavelength converters and parametric amplifiers for fibre optical Wavelength Division Multiplexing (WDM-) communication systems using OBS. The devices take advantage of the high optical nonlinearity of periodically poled Lithium Niobate (PPLN) waveguides exploiting cascaded Second Harmonic Generation / Difference Frequency Generation (cSHG/DFG) and cascaded Sum Frequency Generation / Difference Frequency Generation (cSFG/DFG), respectively.Based on the results of the first project period, the work in the next two years will concentrate on four interdependent topics. The first is a further improvement of the waveguides with respect to nonlinear conversion efficiency and stability. The second is the optimisation of devices with configurations, identified within the 1st project phase as the most promising ones. This also includes a polarisation-insensitive set-up. These devices will be operated and characterized as (tuneable) all-optical wavelength converters for the third telecommunication window - the third topic. At higher pump power levels - and that is the fourth topic - net optical parametric amplification can be achieved. It will first be studied in a pulsed mode of operation. Depending on the waveguide properties also cw-operation should become possible.Specific wavelength converters and parametric amplifiers will be transferred to the project partner HHI for further characterization and investigation in high-speed phase-modulated fibre optical transmission systems.