English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Output power of resonant-tunneling-diode (RTD) terahertz (THz) emitters canbe modulated by the bias modulation similar to a semiconductor laser. Thisproperty is useful for applications of the THz waves to wireless communicationsand radars. In this paper, we theoretically analyze the modulation-frequencydependence of the output response using an equivalent circuit of the RTD-THzoscillator. It is shown that there exists an intrinsic cutoff frequency ofmodulation in RTD, which is independent of the external circuit that suppliesthe modulation signal to the oscillator. This cutoff frequency is determined bythe time constant given by the capacitance of RTD divided by the absolute valueof negative differential conductance minus loss conductance of the oscillator,and is about 100 GHz for typical RTD-THz oscillators. We also analyze theeffect of external feedback injection on the modulation characteristics. If theperiod of the modulation frequency is equal to an integral multiple of theround-trip time of the feedback, a dip or peak occurs in the modulationresponse of the output, depending on whether the THz carrier components in theoutput and the feedback are in phase or out of phase. We also discuss thepossibility of increase in cutoff frequency by the feedback with shortround-trip time.

Intrinsic Frequency Limit of Direct Modulation of Resonant-Tunneling-Diode Terahertz Emitters and Effect of External Feedback Injection