Programming spatial light modulations using mobile electrons*

The perturbations that can be generated by two-dimensional distributions of mobile electrons on visible light fields are usually very weak, which makes their visualizations difficult and also limits their optoelectronic applications. In this study, we demonstrate the reprogrammable spatial light modulations achieved by two-dimensional electron gas structures formed at complex oxide interfaces. This result is enabled by a field-induced polar phase transition at the interface and the related linear electro-optic effect. Using tailored light modulation configurations, nature of the phase transition was systematically studied by visible light imaging. Benefiting from this effect, the fast optical microscopy measurement produced quick visualizations of the interface carrier distributions and real-time monitoring of the surface charge depletion process triggered by the large local field. These results demonstrate the tantalizing possibility of generating designed light manipulations using mature carrier-controlling techniques developed for low dimensional electron systems.