Low Frequency Terahertz Induced Thermoacoustic Signal Characteristics and Its Application in Solid-State Terahertz Transmitter Power Detection

According to the 2019 Federal Communications Commission (FCC) standard, the spectrum range of 6G is 95 GHz to 3 THz. Due to the higher density of 6G base station, a portable, low-cost, and real-time power detection method for transmitters is urgently needed. Therefore, we propose a real-time terahertz (THz) power detection method based on terahertz-thermoacoustic (THz-TA) effect. Using a homemade solid-state THz transmitter (center frequency = 170 GHz, maximum output power = 92.8 mW), we investigate the relationship between THz power, pulsewidth, and THz induced thermoacoustic signal, respectively. Compared with the test results of commercial THz power meter (Erickson-PM5), the feasibility of THz power detection based on THz-TA effect is proved. The experimental results show that the minimum THz power that THz-TA test platform can respond to is 2.8 mW, and the response time is about 0.25 seconds. In the range of 2.8 −92.8 mW, the amplitude of THz-induced TA signal is linear with the output power of solid-state THz transmitter (Pearson's
R
= 0.99571). We also note for the first time that the time interval of THz-induced TA signal is consistent with the pulsewidth of THz signal (0.5, 1, 2, and 5 μs). Therefore, THz-TA technology can not only realize the real-time detection of THz power but also measure the pulsewidth of amplitude-modulated THz signal to a certain extent. We expect that THz-TA detection method will have great potential in the real-time detection of transmitter power of 6G base station in the future.