Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical Communication
The rapid advancement of terahertz (THz) communication systems has positioned this technology as a key enabler for next-generation telecommunication networks, including 6G, secure communications, and hybrid wireless-optical systems. This review comprehensively analyzes THz communication, emphasizing...
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MDPI AG
2025-03-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/25/7/2109 |
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| author | Rahat Ullah Sibghat Ullah Jianxin Ren Hathal Salamah Alwageed Yaya Mao Zhipeng Qi Feng Wang Suhail Ayoub Khan Umar Farooq |
| author_facet | Rahat Ullah Sibghat Ullah Jianxin Ren Hathal Salamah Alwageed Yaya Mao Zhipeng Qi Feng Wang Suhail Ayoub Khan Umar Farooq |
| author_sort | Rahat Ullah |
| collection | DOAJ |
| description | The rapid advancement of terahertz (THz) communication systems has positioned this technology as a key enabler for next-generation telecommunication networks, including 6G, secure communications, and hybrid wireless-optical systems. This review comprehensively analyzes THz communication, emphasizing its integration with free-space optical (FSO) systems to overcome conventional bandwidth limitations. While THz-FSO technology promises ultra-high data rates, it is significantly affected by atmospheric absorption, particularly absorption beyond 500 GHz, where the attenuation exceeds 100 dB/km, which severely limits its transmission range. However, the presence of a lower-loss transmission window at 680 GHz provides an opportunity for optimized THz-FSO communication. This paper explores recent developments in high-power THz sources, such as quantum cascade lasers, photonic mixers, and free-electron lasers, which facilitate the attainment of ultra-high data rates. Additionally, adaptive optics, machine learning-based beam alignment, and low-loss materials are examined as potential solutions to mitigating signal degradation due to atmospheric absorption. The integration of THz-FSO systems with optical and radio frequency (RF) technologies is assessed within the framework of software-defined networking (SDN) and multi-band adaptive communication, enhancing their reliability and range. Furthermore, this review discusses emerging applications such as self-driving systems in 6G networks, ultra-low latency communication, holographic telepresence, and inter-satellite links. Future research directions include the use of artificial intelligence for network optimization, creating energy-efficient system designs, and quantum encryption to obtain secure THz communications. Despite the severe constraints imposed by atmospheric attenuation, the technology’s power efficiency, and the materials that are used, THz-FSO technology is promising for the field of ultra-fast and secure next-generation networks. Addressing these limitations through hybrid optical-THz architectures, AI-driven adaptation, and advanced waveguides will be critical for the full realization of THz-FSO communication in modern telecommunication infrastructures. |
| format | Article |
| id | doaj-art-029dd867cd1a4a4bbd51cd8a3b2a728e |
| institution | OA Journals |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj-art-029dd867cd1a4a4bbd51cd8a3b2a728e2025-08-20T02:09:17ZengMDPI AGSensors1424-82202025-03-01257210910.3390/s25072109Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical CommunicationRahat Ullah0Sibghat Ullah1Jianxin Ren2Hathal Salamah Alwageed3Yaya Mao4Zhipeng Qi5Feng Wang6Suhail Ayoub Khan7Umar Farooq8Institute of Optics and Electronics, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaSchool of Electronic Science and Engineering, Southeast University, Nanjing 210018, ChinaInstitute of Optics and Electronics, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaCollege of Computer and Information Sciences, Jouf University, Sakaka 72388, Saudi ArabiaInstitute of Optics and Electronics, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaInstitute of Optics and Electronics, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaInstitute of Optics and Electronics, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaSchool of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225009, ChinaDepartment of Chemistry, School of Basic Sciences, Galgotais University, Greater Noida 201309, IndiaThe rapid advancement of terahertz (THz) communication systems has positioned this technology as a key enabler for next-generation telecommunication networks, including 6G, secure communications, and hybrid wireless-optical systems. This review comprehensively analyzes THz communication, emphasizing its integration with free-space optical (FSO) systems to overcome conventional bandwidth limitations. While THz-FSO technology promises ultra-high data rates, it is significantly affected by atmospheric absorption, particularly absorption beyond 500 GHz, where the attenuation exceeds 100 dB/km, which severely limits its transmission range. However, the presence of a lower-loss transmission window at 680 GHz provides an opportunity for optimized THz-FSO communication. This paper explores recent developments in high-power THz sources, such as quantum cascade lasers, photonic mixers, and free-electron lasers, which facilitate the attainment of ultra-high data rates. Additionally, adaptive optics, machine learning-based beam alignment, and low-loss materials are examined as potential solutions to mitigating signal degradation due to atmospheric absorption. The integration of THz-FSO systems with optical and radio frequency (RF) technologies is assessed within the framework of software-defined networking (SDN) and multi-band adaptive communication, enhancing their reliability and range. Furthermore, this review discusses emerging applications such as self-driving systems in 6G networks, ultra-low latency communication, holographic telepresence, and inter-satellite links. Future research directions include the use of artificial intelligence for network optimization, creating energy-efficient system designs, and quantum encryption to obtain secure THz communications. Despite the severe constraints imposed by atmospheric attenuation, the technology’s power efficiency, and the materials that are used, THz-FSO technology is promising for the field of ultra-fast and secure next-generation networks. Addressing these limitations through hybrid optical-THz architectures, AI-driven adaptation, and advanced waveguides will be critical for the full realization of THz-FSO communication in modern telecommunication infrastructures.https://www.mdpi.com/1424-8220/25/7/2109THz-bandwidthTHz communication systemsFSO communication systemsintegrated THz-FSO systemssoftware-defined networking |
| spellingShingle | Rahat Ullah Sibghat Ullah Jianxin Ren Hathal Salamah Alwageed Yaya Mao Zhipeng Qi Feng Wang Suhail Ayoub Khan Umar Farooq Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical Communication Sensors THz-bandwidth THz communication systems FSO communication systems integrated THz-FSO systems software-defined networking |
| title | Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical Communication |
| title_full | Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical Communication |
| title_fullStr | Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical Communication |
| title_full_unstemmed | Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical Communication |
| title_short | Beyond Fiber: Toward Terahertz Bandwidth in Free-Space Optical Communication |
| title_sort | beyond fiber toward terahertz bandwidth in free space optical communication |
| topic | THz-bandwidth THz communication systems FSO communication systems integrated THz-FSO systems software-defined networking |
| url | https://www.mdpi.com/1424-8220/25/7/2109 |
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