Fig. 4: Device characterization.
From: Piezoelectrically actuated silicon-nitride-based high-speed spatial light modulator
a The reflection spectrum of the grating (blue) overlapped with the modulation amplitude A as a function of wavelength (orange), measured on an unreleased device at a fixed AC frequency f of 20 MHz for a peak-to-peak voltage of 10 V. b Wavelength shift Δλr/ΔV versus AC frequency f for a released and unreleased device. We used a detector with a 3 dB bandwidth of DC-400 MHz for the released device and 5−1000 MHz for the unreleased device. c Measurement of the different mechanical resonance frequencies fr for each pixel of the strong resonance around 5 MHz and the associated enhancement factor k. 13 of the 16 pixels were functioning in this device. All measurements were done at a wavelength of 791 nm. d Ringdown measurement of the mechanical mode at ~ 5 MHz of a released device. For this measurement we first apply an AC frequency at resonance, then we switch it off and observe how the AC-coupled photodiode signal PAC decays over time t on an oscilloscope. Fitting gives a ringdown time τ of 3.1 μs. e Schematic depiction of our cross-polarized light setup. PBS: polarizing beamsplitter, λ/2: half-wave plate, λ/4: quarter-wave plate.
