Versatile optical frequency comb generation with Bessel spectrum using phase shifters and variable-voltage swing RF amplifiers

商业上可用的光通信系统通过使用一个光载波来实现大约100 Gb/S的数据速率。未来的系统将提供超过1 TB/S的数据速率，以满足通信中日益增长的数据速率需求。使用一个以上的载波可能会显著提高数据速率。在这一应用中，需要设计和研究一种基于新概念的信道间隔为50 GHz(ITU网格)的集成频率梳发生器。首先，电光相位调制器产生一个频率梳，两个远距离载波通过一个可调谐的光子波长选择器在一个输出端分开。这种方法只需要一个单色激光光源。从每个分离的载波中产生另一个频率梳，其中两个梳子被叠加，这显著增加了载波的数量。所有使用的调制器都是由增益可调的射频功率放大器驱动的。该系统的这种灵活性允许产生具有不同载波数目的频率梳。通过在调制器中使用高效的电光聚合物和光子缝隙波导，可以大大减少所需的射频功率，并且可以获得50 GHz的带宽。特别是对于单片集成，效率变得更加重要，因为电路的功率损耗引起的温度变化可能会影响光子组件。因此，重点是研究与驱动调制器的射频功率相关的高效和灵活的几个载波的产生。为了实现这些目标，光电通信工程研究所的光子组和IC组密切合作。

Commercially available optical communications systems achieve data rates of about 100 Gb/s by using one optical carrier. Future systems shall provide more than 1 Tb/s to satis-fy the growing demand of data rates in communications. Using more than one carrier may increase the data rates significantly. In this application, an integrated frequency comb generator with channel spacing of 50 GHz (ITU grid) based on a novel concept shall be designed and investigated. At first, an electrooptical phase modulator creates a frequency comb, from which two distant carriers are separated on one output each by a tuneable photonic wave-length selector. Only one monochromatic laser source is necessary for this approach. Out of each of the separated carriers a further frequency comb is generated, where both combs are superposed, which increases the number of carriers significantly. All used modulators are driven by radio frequency power amplifiers with tuneable gain. This flexibility of the system allows generating frequency combs with different number of carriers. By using highly efficient electrooptical polymers and photonic slot waveguides in the modulators, the necessary radio frequency power can be considerably reduced and a bandwidth of 50 GHz can be achieved. Especially with regard to monolithic integration, the efficiency becomes more important, since the temperature change due to power dissipation of the electric circuit may affect the photonic components. Hence, the emphasis is the investigation of efficient and flexible generation of several carriers in relation to the radio frequency power, which drives the modulators. In order to achieve the goals, the photonic group and the IC group of the Institute of Electrical and Optical Communications Engineering work closely with each other.