A Laser-Induced Traveling-Wave Device for Generating Millimeter Waves

Analysis and design of a continuous-wave terahertz photoconductive photomixer array source

“…The photocurrent's components in a typical photoconductive photomixer can be written as [29] (21) (22) where is the -component of the grating vector , and are the electron and hole velocities, respectively, and are the electron and hole diffusion coefficients, respectively, and …”

Development of a Millimeter-Long Travelling Wave THz Photomixer

“…The most direct way to achieve higher output THz powers is to increase their size beyond a level (>1000 µm 2 ) enabling watt level pump powers easily available by using commercial NIR laser and amplifiers at wavelengths in the range 780 nm -1550 nm. Travelling wave (TW) structures aimed at converting laser beams with time dependent intensities into RF or THz waves have been proposed theoretically many years ago as an alternative to lumped-element photodetectors to obtain large active area/volume devices while keeping large electrical bandwidths [16,17]. In this architecture, TW (photo)currents are induced in a metallic THz waveguide (rectangular waveguide [16] and coplanar waveguide [17]) thanks to a monolithically-integrated photoconductor illuminated by a light beam propagating in the same direction as the THz waves.…”

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

“…In a TW heterodyne photodetector and distributed photomixer designs both optical and THz signals can be co-propagated in an integrated waveguide, while the gradual absorption of optical beat signal in an optical waveguide can produce a THz signal through metallic electrodes in the optical waveguide. The concept of a traveling-wave photomixer has been introduced by J. Soohoo et al 3 and experimentally shown by D. Jager's group 4 for mm-wave signal generation and by S. Matsuura et alin LTG-GaAs up to THz frequencies. 5 The first design integrates both optical heterodyne and mm-wave signal in a strip-loaded ridge waveguide photodetector while the second design uses the angle-tuned free-space optical heterodyning over a THz coplanar waveguide (CPW).…”