A repository & source of cutting edge news about emerging terahertz technology, it's commercialization & innovations in scanners, quality control, process control, medical diagnostics, security, astronomy,communications, graphene, metamaterials, CMOS, compressive sensing,3d printing, and the Internet of Everything. NOTHING POSTED IS INVESTMENT ADVICE! REPOSTED COPYRIGHT IS FOR EDUCATIONAL USE. I am a private investor in THz.
Tuesday, July 28, 2015
Abstract-Unbiased continuous wave terahertz photomixer emitters with dis-similar Schottky barriers
We are introducing a new bias free CW terahertz photomixer emitter array. Each emitter consists of an asymmetric metal-semiconductor-metal (MSM) that is made of two side by side dis-similar Schottky contacts, on a thin layer of low temperature grown (LTG) GaAs, with barrier heights of difference (ΔΦB) and a finite lateral spacing (s). Simulations show that when an appropriately designed structure is irradiated by two coherent optical beams of different center wavelengths, whose frequency difference (∆f) falls in a desired THz band, the built-in field between the two dis-similar potential barriers can accelerate the photogenerated carriers that are modulated by ∆ω, making each pitch in the array to act as a CW THz emitter, effectively. We also show the permissible values of s and ΔΦB pairs, for which the strengths of the built-in electric field maxima fall below that of the critical of 50 V/μm— i.e., the breakdown limit for the LTG-GaAs layer. Moreover, we calculate the THz radiation power per emitter in an array. Among many potential applications for these bias free THz emitters their use in endoscopic imaging without a need for hazardous external biasing circuitry that reduces the patient health risk, could be the most important one. A hybrid numerical simulation method is used to design an optimum emitter pitch, radiating at 0.5 THz.