Terahertz radiation from a large-area photoconductive emitter via high average power Yb-oscillator

Photoconductive emitters excited by fs-lasers are the most commonly used emitters in THz-TDS systems, enabling record high dynamic range and wide bandwidths [1,2]. So far, these emitters have mostly optimized for operation with low average power, low-cost fs-laser systems and have a typical dimension of a few µm^2 for the photoconductive gap [3]. In parallel, large-area emitters with mm^2 size have been explored for scaling fluence and obtaining high fields [4]. However, so far, no attempts have been made of using high average power laser systems as excitation sources, as a possible path to increase the THz source average power and reach even higher dynamic range than current reported records. In this work, we present our first results in this direction and show THz emission from a large area photoconductive emitter (LAE) based on SI-GaAs with a 1×1 cm^2 active area, excited by a frequency-doubled home-built high average power ultrafast oscillator, capable of 92 fs at a centre frequency 515 nm with 90 MHz repetition rate and 17 W of average power. We show here preliminary results exciting the LAE with 1 W from this laser system, which is to the best of our knowledge the highest average power applied to such an emitter, without any apparent sign of thermal saturation.
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