Detect small first-order diffraction intensity modulation in bonded LNoS devices

Ascertain whether the bonded Lithium Niobate–on–Silicon Nitride guided-mode resonance spatial light modulator, integrated with a CMOS backplane and epoxy layer, produces a measurable change in the first diffraction order intensity under the reported operating conditions, where modeling predicts approximately 0.09% to 0.7% modulation, given that experimental detection was not achieved.

Background

To evaluate performance when scaling to megapixel apertures, the authors simulated the electric field profile and associated refractive index modulation in the bonded LNoS stack. Fourier analysis and coupled mode theory predict small changes in the first diffraction order intensity (ΔI1), on the order of ~0.7% without epoxy and ~0.09% with a 400 nm epoxy layer.

Despite observing thermal modulation due to local backplane heating, the authors explicitly state they were unable to experimentally detect these small intensity modulations, leaving open the question of measurability under the current device configuration and indicating potential needs for improved materials, higher-Q resonances, or measurement sensitivity.