arXiv subjects

Feifan Han

Publications and source records attributed to Feifan Han.

3 recordsLinked to original sources

arXiv2025

Electrically Pumped Terahertz Frequency Comb Based on Actively Mode-locked Resonant Tunneling Diode

Terahertz (THz) frequency combs (TFCs) are promising for numerous applications in spectroscopy, metrology, sensing, and wireless communications. However, the practical applications of TFCs have been hindered thus far by the need for cryogenic cooling, limited bandwidth, and bulky configuration, largely due to the lack of advanced THz sources. Here, we report an electrically pumped, room-temperature, broadband, compact, and tunable TFC by integrating an actively mode-locked resonant tunneling diode (RTD) in a metallic waveguide. By injecting a strong, continuous-wave radio frequency (RF) signal into a direct-current-driven RTD oscillator, we experimentally demonstrate a broadband, offset-free comb spectrum spanning more than one octave, from 0.14 to 0.325 THz at room temperature. Moreover, we show that the repetition frequency of the TFC can be tuned from 0.9 to 50 GHz by the injected RF signal, and a 120 Gbps (16 Gbps per channel) data rate can be achieved in the TFC-based high-speed single-channel (multi-channel) wireless communications.

physics.app-ph↗

arXiv2025

Broadband Terahertz Frequency Comb Based on Actively Mode Locked Resonant Tunneling Diode

The frequency combs characterized by their phase-coherent equidistant spectral modes and precise frequency scales of broadband spectrum, have made them an indispensable part of contemporary physics. A terahertz (THz) frequency comb is a key asset for THz technology applications in spectroscopy, metrology, communications, and sensing. However, the THz frequency comb technologies are comparatively underdeveloped compared to the optical frequency domain, primarily attributed to the deficiency of advanced THz generation components. In this paper, we innovatively demonstrate a compact THz frequency comb source based on a resonant tunneling diode (RTD) through active mode locking technique. By injecting a strong continuous-wave radio frequency (RF) signal via the bias line into a RTD oscillator integrated within a WR-5 hollow metallic waveguide package, we observe a broadband comb spectrum spanning from 140 to 325 GHz. The mode spacing is directly determined by the frequency of the injected RF signal, providing a wide tuning range of approximately 40 GHz. We also employ the proposed frequency comb source as the local oscillator in a coherent transmitter. In particular, this is the first all-electrical compact THz frequency comb source, and the transmission demonstration paves the way to next-generation communication.

physics.app-ph↗

arXiv2025

High Gain and Broadband Metalens Antenna for Terahertz Communication

Terahertz (THz) metalens antennas with compact planar structures have demonstrated significant potential in enhancing gain and aperture efficiency through beam convergence. However, research on THz wireless communication systems utilizing metalens antennas remains limited, primarily due to insufficient collaborative enhancement in gain and bandwidth in THz transceiver design. In this paper, we propose a high gain metalens antenna transceiver and demonstrate its application for THz communication. The system employs a horn antenna integrated with a 3D-printed bracket to enhance the metalens gain and operating bandwidth, where the metalens adopts a "sandwich" architecture composed of a V-shaped copper resonator, a dielectric substrate, and a grating. The resonant design inside the metalens facilitates high polarization conversion efficiency and full phase modulation across a 0{\deg} to 360{\deg} range at frequency between 0.20 to 0.30 THz band. Experimental results demonstrate a peak gain of 36.1 dBi and aperture efficiency of 54.45% at 0.244 THz, with a 3 dB bandwidth exceeding 33 GHz. A prototype communication system incorporating the metalens transceiver achieves a bit error rate (BER) reduction by three orders of magnitude compared to conventional horn antennas and supports a maximum data rate of 100 Gbps. This proposed metalens offer a high-gain, compact solution for achieving high data rate THz communications, driving advancements in 6G communication network.

physics.app-ph↗