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Polarization plays a critical role in optical systems that range from optical communications to imaging, lithography, metrology, and data storage. Thus, in systems that need to generate a certain polarization state, a light source (e.g., laser) is combined with polarization control elements such as polarizers, polarizing beam splitters, and waveplates. Similarly, in systems requiring polarization state detection, such elements are combined with photodetectors. There is currently a trend toward miniaturized optical systems. This motivates the question of how to achieve what may be argued as an ultimate level of miniaturization: a single chip that can both generate light with a prescribed polarization state and detect the polarization state of light impinging upon it. This paper demonstrates this via vertical cavity surface emitting lasers (VCSELs) with on‐facet metasurfaces. Two classes of devices are demonstrated. The first class uses high‐index dielectric metasurfaces (amorphous silicon nanofins), whereas the second class uses plasmonic metasurfaces (aluminum bilayer gratings). Each can operate as a laser (to generate) and as a photodetector (to detect) circularly or linearly polarized light. [ABSTRACT FROM AUTHOR]

One of the most fundamental quantum random number generators is implemented with light impinging onto a beam splitter, and two single photon detectors at its output. Often, this generator is described as 'a photon which takes one or other path towards a detector'. The input state of light in conjunction with the detector response is relevant for the amount, the pattern, and the correlation of the generated clicks. Only a fraction of all generator outcomes, the min-entropy, can be used as a further resource for true randomness. This paper addresses the difference in the common description with incoming single photons and the often implemented scheme with a weak coherent light source, such as an attenuated laser. For this very fundamental and widely used configuration the amount of usable entropy is compared. If single photons from an anti-bunched light source are supplied, the amount of entropy is higher than for the case of a supplied coherent state - although the latter can be arbitrarily bright unlike the single photon source. [ABSTRACT FROM AUTHOR]

Many optical systems for displaying digital information on mirrors have been proposed, but information can only be displayed in either mirrored or real space and cannot move back and forth between the two. We have therefore developed a new optical system called mirror-transcending aerial imaging (MiTAi) that freely crosses the boundary between mirrored and real spaces. MiTAi is based on an existing aerial-imaging system consisting of a retroreflector, a beam splitter, and a moving display. MiTAi is designed as a spacesaving design by changing the orientation and position of the moving display as the light source. We implemented a prototype MiTAi to evaluate the luminance of the displayed aerial images and found that the aerial image formed by the prototype is able to move freely between both mirrored and real spaces. Moreover, the luminance of the image is not significantly lower than that formed by the existing aerial-imaging system. MiTAi will enable the creation of a new user experience by integrating smart mirrors and real-space aerial images. [ABSTRACT FROM AUTHOR]