Frequency increase in resonant-tunneling diode cavity-type terahertz oscillator by simulation-based structure optimization

Abstract

Terahertz (THz) radiation, in the range between the light waves and millimeter waves, has gained much attention because of its various promising applications. Resonant tunneling diodes (RTDs) have the potential for use as compact and coherent THz sources operating at room temperature. In this paper, oscillation frequency limitations and structure dependences for a RTD THz oscillator with a cylindrical cavity resonator are analyzed. Based on the dependences of the oscillation frequency on resonant cavity dimensions, a method of the oscillator structure optimization and matching with an RTD structure was proposed. It is revealed that there is only one combination of the resonant cavity dimensions which gives the maximum possible oscillation frequency for this type of structure. Analysis of the calculation results has shown that fundamental oscillation up to 2.77 THz could be expected for the RTD device considered in the present study by using the proposed optimization technique.

Discrete Fourier Transform Radar in the Terahertz-Wave Range Based on a Resonant-Tunneling-Diode Oscillator

“…As the RTD output powers and available oscillation frequencies progressively improve with ongoing research, we anticipate that the range of applications will widen, in a way that might parallel the history of devices such as the light-emitting diode. Currently, RTD oscillation frequencies up to 1.98 THz are demonstrated [ 17 ], although simulations show it could reach even higher, to about 3 THz [ 18 ]. The output power is now in the microwatt order, but an incoherent array of RTDs was shown to emit 0.73 mW [ 19 ] and research is ongoing toward a single-element power emission of several milliwatts [ 20 , 21 ].…”

Terahertz Emitter Using Resonant-Tunneling Diode and Applications

“…As the surface area of the cavity is large, the conduction loss is small and high-frequency oscillation is expected. A theoretical calculation [ 34 ] has shown that oscillation up to approximately 2.8 THz is possible by optimizing the radius and height of the cylindrical cavity, as shown in Figure 6 b. In a preliminary experiment, 1.78 THz oscillation has been obtained for a non-optimized structure with parasitic capacitance [ 33 ].…”

“… RTD oscillator integrated with cylindrical cavity and bow-tie antenna for high-frequency oscillation [ 33 , 34 ]: ( a ) Oscillator structure, and ( b ) calculation of oscillation frequency as a function of cavity height and radius. Copyright (2020) The Japan Society of Applied Physics [ 34 ]. …”

“…Resonant-tunneling diodes (RTDs) are also promising candidates for room-temperature THz sources [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Currently, oscillation up to 1.98 THz has been obtained at room temperature [ 32 , 33 ], while structures for higher frequency and high output power are being studied [ 34 , 35 ]. Studies aiming toward several applications, such as imaging, spectroscopy, wireless communications, and radars, have recently begun [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ].…”

Passive mode-locking and terahertz frequency comb generation in resonant-tunneling-diode oscillator

“…The RTD oscillator is an electrical device with fundamental oscillation frequency in the terahertz frequency range at room temperature [16]. Oscillation from the sub-terahertz to 1.98 THz range has been achieved [17][18] [19][20] [21], and oscillation up to 2.77 THz is expected [22]. A single oscillator can be fabricated on a millimeter-sized chip [23].…”