Considering the reduction of the illuminated area as well as coupling losses at pinholes and beam splitters, this action changes the irradiance from roughly 0.4 to 400 W/cm 2 . Most importantly, the photoresistance in the steady state measurements decreases by a factor of 23, from 82.7 MΩ to 3.6 MΩ, leading to the greatly increased response time shown in red in Figure . This correlation indicates an RC limitation of the device. For the non-steady state measurements, the impulse response (f(t)) is fast Fourier transformed (FFT) to obtain the power spectrum (P(ω)): P(ω)=|FFT(f(t))| 2 . After conversion to the dB scale, via dB = 10𝑙𝑜𝑔 10 (𝑃(𝜔) 𝑃 1 ⁄ ) with the steady state power 𝑃 1 , the 3 dB bandwidth, i.e., the frequency, at which the power has fallen to half its value, can be read out. Comparing the two values for the unfocussed and focussed measurement again reflects the factor 23, the dependence on the photoresistance, and supports the hypothesis of RC-limitation. The non-normalised square pulse measurements can be seen in Fig. . ON/OFF measurement taken after six months (Figure ) reveal ratios > 10 4 and long-term stability under ambient conditions. )) and 𝑘 ′ = √ 1 -𝑘². The width w of the electrodes is 10 µm in the optical lithography structure and the gap g between the two electrodes is 2.5 µm.