Abstract
Towards exploring advanced applications of terahertz (THz) electromagnetic waves, great efforts are being applied to develop a compact and sensitive THz receiver. Here, we propose a simple coherent detection system using a single resonant tunnelling diode (RTD) oscillator through self-oscillating mixing with an RTD oscillator injection-locked by a carrier wave. Coherent detection is successfully demonstrated with an enhancement in the sensitivity of >20 dB compared to that of direct detection. As a proof of concept, we performed THz wireless communications using an RTD coherent receiver and transmitter. We achieved 30-Gbit/s real-time error-free transmission, which is the highest among all electronic systems without error correction to date. Our results show that the proposed system can reduce the size and power consumption of various THz systems including sensing, imaging and ranging, which would enable progress to be made in a wide range of fields in such as material science, medicine, chemistry, biology, physics, astronomy, security, robotics and motor vehicle.
Highlights
Towards exploring advanced applications of terahertz (THz) electromagnetic waves, great efforts are being applied to develop a compact and sensitive THz receiver
When the received carrier frequency from the Tx is set within the locking range of the local oscillator (LO) frequency, the self-oscillating mixer (SOM) will be injection-locked to the carrier signal, and coherent detection can be achieved in a single device
We proposed a simple coherent detection system in the THz band using an resonant tunnelling diodes (RTDs) oscillator
Summary
Towards exploring advanced applications of terahertz (THz) electromagnetic waves, great efforts are being applied to develop a compact and sensitive THz receiver. One of the major methods for coherent detection at THz band is digital signal processing for the IF signal[30] Another is synchronisation between the Tx and the Rx using a low-frequency reference signal with frequency multipliers for THz operations[31]. For developing a simple synchronisation system between the Tx and the Rx, we can apply an injection-locking phenomenon to a self-oscillating mixer (SOM) as the Rx32, which is a self-oscillating electronic device with a non-linear current–voltage (I–V) characteristic that acts as a mixer to demodulate a data signal. If we enhance the sensitivity by coherent detection using an RTD as an injection-locked SOM, the data rate will be significantly increased
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