# Revealing Development Trends and Key 5G Photonic Technologies Using Patent Analysis
## 1 Introduction  
Photonics is a science that explores the use of photons as information and energy carriers [1]. Photons are characterized by a lack of electric charge and mass, low energy consumption, and insusceptibility to external influences. They can solve problems related to electromagnetic interference-induced operation delays and energy loss due to the shortened distance between components and wires arising from the miniaturization of semiconductors. Accordingly, photons have become a crucial emerging technology in the post Moore's Law era, with photonic technology being one of the five technologies proposed as key enabling technologies by the European Union's Horizon 2020 program [2]. Electric signals can be converted into optical signals through photonic technology to transmit data in order to increase transmission distance and data bandwidth while reducing energy consumption, all of which are huge potential advantages in cloud computing, the Internet of Things (IoT), and 5G networks [3; 4; 5; 6]. The development of 5G satisfies the requirements of the connection between people and the connection between objects. 5G communication is 100 times faster than 4G communication, with only one-tenth of 4G's delay time. The other benefits of 5G over 4G can be further defined in three application scenarios. The first of these scenarios is enhanced mobile broadband that supports more efficient data transmission through improved network coverage and capacity, such as virtual reality, augmented reality, and other computationally intensive experiences [7]. The second benefit is the promotion of massive IoT application services in fields such as smart homes and smart cities [8; 9]. According to Gartner, a global research and advisory firm, the world is expected to have over 20 billion connected objects in use by 2020 [10]. Finally, 5G is a key technology in many growth sectors that provide key services, such as autonomous vehicles, smart factories, and smart healthcare [11; 12; 13]. These service applications, which were previously constrained in speed and stability under 4G networks, could be implemented following the advent of 5G. Preliminary discussions have been conducted with regard to the use of 5G photonic technology [4; 14; 15]. Because next-generation (5G) wireless communication systems require the high-speed processing of considerable amounts of data and a wider bandwidth, bandwidth has become increasingly important; transmission technologies require a substantial number of antennas [14]. Photonic technology is the key technology for the future of 5G. The realization of 5G network infrastructure will considerably benefit from advanced photonic technologies to fulfill those requirements [16]. In the future, the long-distance transmission of considerable amounts of data will directly enter terminal machines, or even memory or processing chips, in the form of optical signals. Because the application of 5G is not limited to consumer mobile communication (its application includes Internet services such as IoT, automated vehicles, and smart homes) and photonic technology is the key technology for the implementation of 5G, this study focused on 5G photonic technology and explored the relevant key technologies and their development trends. The study results may serve as references for governments and the industry for the allocation of research and development resources and the formulation of research and development directions. Previously, research on 5G photonic technology mainly focused on technical discussion [4; 14; 17] or market development research [3; 16; 18]. These studies have not actively discussed the key areas of photonic technology in 5G development. In particular, the development of 5G involves numerous technological fields [12; 13; 19], and holds the potential for unlimited business opportunities in the future. Patents are the manifestation of technology industrialization, and patent application is conducive to providing business opportunities that monopolize the technology market.