20 Mbit/s wireless communication demonstration using terahertz quantum devices
Scheme of the transmission setup based on a THz QCL and a THz QWP.
Terahertz communication (0.1~10 THz) has attracted much attention due to the high carrier frequency and large bandwidth over 100 Gbps. At present, most of the research work is focused on the frequency of 100 ~ 600 GHz, some has made good results by using the mature technology of component manufacturing and communication for microwave and millimeter-wave wireless communication. However, high speed communication system has not yet been realized in the carrier frequency between 1~10 THz. The communication demonstration system with carrier frequency between 1~10 THz relies largely on THz quantum cascade lasers (QCLs) and THz quantum-well photo-detectors (QWPs) as the emitter and receiver, respectively.
With a THz QCL and a frequency well-matched THz QWP set up for THz communication system, a data signal transmitted over a 2.2 m and data rate as high as 20Mbps was realized, and photocurrent extraction circuit was improved by Prof. Juncheng Cao's research group, from Key Laboratory of Terahertz Solid-State Technology, Chinese Academy of Sciences, based on their previous work. It is reported in Chinese Optics Letters, Vol. 13, No. 8, 2015 (Li Gu et al., 20 Mbps wireless communication demonstration using terahertz quantum devices).
The THz QWP matching the emitting frequency of the THz QCL can make sure that the QWP achieves more than 90% responsivity for the THz wave emitted from the QCL, which greatly improves the photocurrent outputting from the QWP. With the current extraction circuit enhanced according to THz QWP small signal model , the signal-to-noise ratio is improved while the bandwidth of the link increases to 11.8 MHz.
For the first time as far as we know, more than 20 Mbps wireless communication demonstration between 1~10 THz carrier frequency has been achieved. The results provide a feasible scheme for terahertz communication, and using THz QCLs and THz QWPs to build the THz high speed communication system has a great potential.
The following work will be focused on researching the high performance THz communication key devices, developing the high-speed THz modulation technology, improving the circuit bandwidth and realizing the THz high-speed communication systems.