We report the experimental observation of classical subwavelength double slit interference with a pseudothermal light source. The experimental results are in good agreement with the theoretical simulation using the second order correlation function for the thermal light.
Optical metasurfaces can offer high-quality multichannel displays by modulating different degrees of freedom of light, demonstrating great potential in the next generation of optical encryption and anti-counterfeiting. Different from the direct imaging modality of metasurfaces, single-pixel imaging (SPI) as a typical computational imaging technique obtains the object image from a decryption-like computational process. Here, we propose an optical encryption scheme by introducing metasurface-images (meta-images) into the encoding and decoding processes as the keys of SPI encryption. Different high-quality meta-images generated by a dual-channel Malus metasurface play the role of keys to encode multiple target images and retrieve them following the principle of SPI. Our work eliminates the conventional digital transmission process of keys in SPI encryption, enables the reusability of a single metasurface in different encryption processes, and thereby paves the way toward a high-security optical encryption between direct and indirect imaging methods.
The arbitrary Nth-order intensity correlation measurement with thermal light is both theoretically and experimentally investigated. In a double-slit interference scheme with thermal light, we compare the results for higher- and lower-order intensity correlation and demonstrate that the visibility of the interference pattern can be dramatically enhanced while the resolution can also be improved when the order N becomes larger. The experimental results are in agreement with our theoretical analysis.
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