THz signal generation/propagation in an integrated traveling-wave superconductive/photoconductive heterodyne photodetector

Abstract

The ultrafast and sensitive detection of an optical beat signal generated from an optical heterodyne system in an integrated traveling-wave photoconductive detector with high-temperature superconducting (HTS) coplanar electrode lines has been introduced for generating THz signals.While the optical beat signal has been absorbed by photoconductive substrate and an HTS center strip, the THz signal is gradually bulit up on the HTS coplanar waveguide (CPW). The kinetic inductive photoresponse of the HTS strip contributes excessively in the generation of multi-THz signal while the response of the photoconductor substrate decreases with increasing THz frequency. A rigorous optical analysis of a multilayer waveguide in conjunction of optical-to-THz signal conversion analysis have been carried out to find the external conversion efficiency of such a photodetector. Our simulation shows that the GaAs-based structure with YBCO electrode at1.5 µm exhibits more output THz power than its Si counterpart in 850 nm wavelength.

Surface plasmon-assisted propagation of optical waves in superconducting active waveguides

“…In particular, superconducting traveling-wave photodetectors (STWPDs) are novel devices that can be used for ultra-sensitive and ultra-fast photodetection [1], [2] as well as generation of THz signals in the form of traveling-wave photomixers [3]. STWPDs consist of a biased superconducting thin film integrated with an optical waveguide and a microwave transmission line.…”

Microwave and millimeter-wave generation in superconductive traveling-wave photomixers

“…This fact, provokes the idea that these devices can be customized as traveling-wave photomixers. The device detects the beat frequency of two off-tuned input optical signals and generates microwave/mm-wave output [5], [6]. …”

Terahertz transmission lines based on surface waves in plasmonic waveguides

“…19,20 While the propagation along MD-SWGs at optical wavelengths is lossy, low-loss propagation of visible and near IR waves is achievable based on the long-range surface plasmon polaritons ͑SPPs͒ in other structures such as symmetrically loaded metal slabs 21,22 and stripes 23 as well as metal-clad waveguides. Furthermore, these models are particularly useful for the analysis and design of terahertz traveling-wave devices such as traveling-wave photomixers [27][28][29] and detectors. 25,26 The low-loss and quasi-TEM nature of terahertz waves propagation in PPWGs and MD-SWGs provokes the idea of employing the transmission line ͑TL͒ theory to study these structures.…”