Microlens coupled interdigital photoconductive switch

Matthäus, Gabor; Nolte, Stefan; Hohmuth, Rico; Voitsch, Martin; Richter, Wolfgang; Pradarutti, Boris; Riehemann, Stefan; Notni, Gunther; Tünnermann, Andreas
September 2008
Applied Physics Letters;9/1/2008, Vol. 93 Issue 9, p091110
Academic Journal
A large-area terahertz emitter based on an interdigital finger electrode photoconductive switch on low-temperature grown GaAs attached to a hexagonal microlens array is demonstrated. The hexagonal arranged microlenses direct the incident IR excitation pulses into specified electrode gaps, resulting in constructive interference in the terahertz far field. Using a Ti:sapphire oscillator running at 80 MHz with 150 fs pulses, 6.5 μm THz average power at 540 mW optical excitation is obtained. The maximum IR-to-terahertz conversion efficiency achieved is >=1.35×10-5.


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