Toward Terabit Receivers for Optical and Wireless Communications

Data rates and bandwidths in global optical communication networks and their wireless access are continuously rising as a result of new applications. Besides communication, high bandwidth devices are also needed for radar, sensors and measurement systems. These increasing bandwidths might lead to problems for the electronic analog-to-digital converters (ADC) in the digital systems. A 1Tb/s, 16-QAM modulated data signal, for instance, needs an analog processing bandwidth of 80 GHz, which is far beyond the possibilities of today's standard CMOS technology. Additionally, higher bandwidths are accompanied by a lower conversion resolution, which requires higher signal-to-noise ratios for the signals to be detectable. Here we discuss these connections and review possibilities for a solution by a photonics assisted parallelization of the incoming high bandwidth signal into several low bandwidth sub-signals in the time and frequency domain. These sub-signals can then be detected and processed with low bandwidth electronics, circumventing the CMOS bandwidth problem. This review primarily focuses on bandwidth reduction using time-frequency coherence. Since it only needs low bandwidth standard electronics and photonics, the seamless integration with the electronic ADCs into any electronic-photonic platform is straightforward. Therefore, it could become an important component of future terabit receivers in optical and wireless communication.