Photonic Technologies for Terahertz Wireless Communication Systems

无线通信系统是现代社会不可缺少的一部分。在全国范围内，无线行业为国内生产总值贡献了235亿美元，投资27亿美元，创造了13.41万个就业岗位。在国际范围内，无线产业占全球国内生产总值（gdp）的近4%，在236个国家贡献了3.8万亿美元。然而，现有的无线技术面临着一个迫在眉睫的挑战。当代无线系统依赖于射频技术，其载波频率跨越3khz至300ghz，但对射频系统的需求每18个月翻一番。由于许可的无线电频带数量有限，我们现在目睹了容量的限制。频谱短缺是该行业的一个严重问题。

Wireless communication systems are an integral part of modern society. On a national scale, the wireless industry contributes $23.5 billion to the gross domestic product, $2.7 billion in investments, and 134,100 jobs. On an international scale, the wireless industry generates nearly 4% of the global gross domestic product, with $3.8 trillion in contributions spanning 236 countries. However, there is a looming challenge for the existing wireless technologies. Contemporary wireless systems have relied upon radio-frequency technology, with carrier frequencies spanning 3 kHz to 300 GHz, but the demand for radio-frequency systems has doubled every 18 months. We are now witnessing capacity limitations due to the limited number of licensed radio-frequency bands. Spectrum scarcity is a serious concern for the industry. Optical wireless systems emerged in response to the above concern. These free-space systems typically apply line-of-sight infrared links, with carrier frequencies spanning 10 THz to 300 THz, to offer ultra-high data rates and wireless mobility. However, the systems have been found to have practical challenges related to incoherent detection, strong ambient light noise, and eye-safety restrictions. It is because of these challenges that new concepts in wireless communications are being pursued. The proposed research program looks toward the terahertz band, with carrier frequencies spanning 300 GHz to 10 THz, as a solution to the above challenges. The terahertz band lies between the radio-frequency spectrum and infrared spectrumand it has notable benefits. Like the infrared spectrum, it has sufficiently high frequencies to enable unlicensed operation and high data rates. Like the radio-frequency spectrum, it has sufficiently low frequencies to enable coherent detection. Such terahertz wireless communication systems have unresolved challenges, however, and it is these challenges that are targeted by the proposed research program. The proposed research program leverages a series of pilot studies that the applicant has conducted over the previously-funded NSERC Discovery Grant. The studies demonstrated the feasibility of new terahertz technologies (for deployment with low power consumption) and new optical wireless technologies (for implementation via active downlinks and passive uplinks). The proposed research program will take this work to the next level by integrating terahertz and optical wireless technologies in the form of new terahertz communication devices and systems. Through a series of international partnerships, the work will materialize as multi-gigabit-per-second and terabit-per-second links that can enable seamless integration between wired networks and wireless terahertz networks. Terahertz technology is at the frontier of wireless communicationsand its potential is significant.