High SHF band RF Signal over Multi-Mode Fiber Employing Directly Modulated VCSEL

Abstract

The mobile traffic has been increased with progress of cellular phone and mobile devises [1]. The Internet of Things (IoT) is also one of its factors. The IoT applies much data through wireless communication. To increase the capacity of wireless communication, using of high SHF band RF signal with high bandwidth is considered such as the 5th generation mobile access system (5G). On the other hand, there is concern for increasing of radio insensitive area due to high free space propagation loss and directivity of high SHF band signals. The radio over fiber is candidate for radio signal relay technique to solve these concerns [2]. Particularly, radio over multimode fiber has the advantage of the cost because of relaxed alignment tolerance and simplified packaging. Furthermore, the optical waveform transmission is suitable for relay of RF signals in terms of high spectral efficiency and low latency transmitting. From these motivations, we have tried analog radio over multi-mode fiber (A-RoMMF) transmission employing directly modulated Vertical Cavity Surface Emission Laser (VCSEL) for SHF band signal with 200 MHz bandwidth at carrier frequency of up to 28 GHz.