Silicon photonics to improve the energy-efficiency of millimeter wave communication systems

Bandwidth limitation of current wireless frequency bands and the energy consumption are challenges that have to be addressed by future 5G wireless networks. The millimeter wave (mm-wave) spectrum, spanning 30 GHz to 300 GHz, is a prime candidate to resolve the bandwidth limitation issue in future networks. High-speed electronics, though, are quite energy-inefficient for such mm-wave signal generation. Photonic-based sources are an alternative to provide the required frequencies and bandwidth, i.e., the field of microwave photonics. One promising technique to generate mm-waves is to modulate a single frequency laser at a relatively low frequency to generate a frequency comb. By beating two non-adjacent comb lines, a higher frequency beat note is generated. However, it is unclear yet how a photonic-based solution compares to an electronic-based solution in terms of energy-efficiency. In this work we theoretically explore the use and the energy-efficiency of mature silicon photonic integrated circuits to achieve mm-wave generation on a chip. We do this by setting up a simulation tool for calculating the energy consumption of the silicon photonic integrated circuit, including electronic driver power consumption. It is shown that silicon photonics based mm-wave generation is more efficient than electronic-based solutions for mm-wave frequencies exceeding 60 GHz. If transport is included, i.e., over a length of cable to reach remote antenna, it is shown that for mm-wave frequencies above 20 GHz and lengths over 3 m, silicon photonics is again more energy-efficient solution. This analysis shows that silicon photonic integrated circuits are a viable candidate for mm-wave generation in future 5G networks, for reasons of compact footprint, maturity of the technology and energy-efficiency.