Integrated, Portable, Tunable, and Coherent Terahertz Sources and Sensitive Detectors Based on Layered Superconductors

Abstract

At terahertz (THz) frequencies, between 0.1-10 THz, current compact emitter and receiver technologies are generally inefficient and impractical. Hence, a gap exists between mature microwave and developed optical technologies. On-chip, integrated broadly tunable and powerful quantum sources that coherently radiate THz waves between 0.1 and 11 THz (potentially extendable to 15 THz) and with potential output power of > 1 mW can be achieved based on quantum tunneling of electron pairs across the stack of intrinsic Josephson junctions (IJJs) naturally present in a single crystal of the layered high-Tc superconducting Bi2Sr2CaCu2O+ (BSCCO). Such devices have been found to be especially promising solid-state THz sources capable of bridging the entire THz gap, as their wide frequency tunability range is superior to that obtained from their semiconducting based rivals, either single resonant tunneling diodes (RTDs) or THz-quantum cascade lasers (QCLs). Due to the unique electrodynamics of BSCCO, they can also be operated as switching current detectors, paving the way for the realization of on-chip THz integrated circuits for applications in ultrahigh-speed telecommunications, quantum information, on-chip spectroscopy, and non-destructive sensing, testing, and imaging. This paper reviews the history and recent advances in THz sources and detectors based on IJJs with a focus on the application of IJJ THz devices in THz spectroscopy, and various types of THz imaging systems such as r eflection, transmission, and computed tomography. We show that compact IJJ THz devices with sub-centimeter-sized modules are easy to use in many applications, as they can be regarded as pocket quantum THz torches.

Finite-Frequency Dissipation in Two-Dimensional Superconductors with Disorder at the Nanoscale

“…We remark that the electrodynamic properties of nanopatterned superconductors, and their exploitation in technological applications and device design, are attracting an ever- increasing interest (for recent examples, see in [ 35 , 36 ]). We think that a better understanding of situations in which the nanopatterning may be random (or self-organized), like the case we are considering, can lead to the manipulation and technological exploitation of superconductors with disorder at the nanoscale.…”

Millimeter-Wave-to-Terahertz Superconducting Plasmonic Waveguides for Integrated Nanophotonics at Cryogenic Temperatures

“…The conductivity of gold ( ) is described by the Drude model expression as where plasma frequency is THz and collision frequency is THz [ 1 ]. Here, is the vacuum electric constant.…”

“…The high-transition-temperature ( T c ) superconducting Bi 2 Sr 2 CaCu 2 O 8+δ (BSCCO) intrinsic Josephson junctions (IJJs)-based THz emitters radiate intense, coherent, and continuous THz photons with frequencies ranging from 0.1 to 11 THz [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Such THz devices can also be used as surface current-sensitive detectors due to the unique electrodynamics of the BSCCO quantum material.…”

Widely Tunable Terahertz‐Generating Semiconductor Disk Laser

“…Recently, THz frequency combs based on difference‐frequency generation (DFG) from a mid‐infrared QCL [ 17,18 ] have provided another effective approach to generating THz at room temperature, although the THz output is still in the range of a few microwatts. Recently, also intrinsic Josephson junction devices were reported to emit sub‐mW power levels of THz and showed broad THz tunability, however, their operation is currently only ensured below 77 K. [ 19 ]…”