Abstract
Millimeter wavelength (mmWave) electromagnetic waves have found recent use in the deployment of the fifth generation (5G) of cellular data. In just 2021, 5G accounted for 10% of the total global data traffic and is forecasted to rise to 60% in 2027 [1].However, mmWave bands are limited in penetrative abilities and often require line-of-sight (LOS) connection with signal drops occurring frequently. This leads to limitations in the scalability of mmWave data communications and widespread expansion of 5G and future 6G. To facilitate the expansion of mmWave, small transceiver cells integrated with existing fiber optic networks through radio frequency over fiber (RoF) can provide a viable solution. Radio over fiber is used for transmitting RF signals over long distances through optical fiber. The advantages of RoF include lower loss, improved flexibility, immunity to electromagnetic interference, and most importantly higher data capacity. This work presents the theory, design, and experimental results of two potential solutions for mmWave integration with RoF. The first solution presented is the usage of optical frequency down-conversion where an RF signal can be frequency down-converted using two lasers interfering. This solution is verified experimentally using commercially available bulk lithium niobate modulators at X-band. The second solution combines classical electrical receiver architecture with a high intermediate frequency compatible with conventional RoF links. The modeling and design work includes the creation of a wideband antenna resonant at 82GHz and layout of the necessary commercial off the shelf parts to perform electrical down-conversion.