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Stimuli-Responsive Materials: Smart Compound Eyes Enable Tunable Imaging (Adv. Funct. Keywords: compound eyes; femtosecond laser; smart materials; tunable optical components; variable-focus imaging Compound eyes, femtosecond laser, smart materials, tunable optical components, variable-focus imaging. [Extracted from the article]

Compound eyes are natural multiaperture optical imaging systems and have substantial potential in the field of modern optics. However, both natural and artificial compound eyes are composed of ommatidia with fixed focal lengths, and thus incapable of variable‐focus imaging. In this study, inspired by the tunable crystalline lens of human eyes, smart stimuli‐responsive compound eyes based on the bovine serum album (BSA) protein are fabricated via femtosecond laser direct writing. Due to the swelling and shrinking effect of BSA under different pH conditions, a tunable field of view (FOV, 35°–80°) and variable focal length of ommatidia are achieved. In addition to the direct prototyping of an entire protein‐based compound eye, the ability to flexibly integrate the smart protein ommatidia with a conventional optical lens (an SU‐8 lens in this study) to form a composite compound eye is shown. The composite compound eye achieves nearly 400% of focal length tuning at a fixed FOV. It is anticipated that femtosecond laser fabrication and the integration of smart protein‐based compound eyes may emerge as an enabler for fabricating miniature tunable imaging systems. [ABSTRACT FROM AUTHOR]

On‐chip polarization manipulation is proposed via a waveguide that is adiabatically twisted along its longitudinal axis, which can be fundamental building blocks for polarization‐encoded optical communication and information processing. With the help of femtosecond direct laser writing, the polarization rotators for both telecom and visible wavelengths are fabricated, which show polarization conversion efficiencies of >90% at 1550 nm and ≈80% at 646 nm, respectively. Furthermore, a polarization router consisting of multiple waveguides with different twisting angles is demonstrated. With the polarization router, photons with different polarizations are directed to different paths. Based on such platform, the path entanglement between the photons can be transformed to polarization entanglement, which will extend the quantum information technology to higher‐dimensional Hilbert space. [ABSTRACT FROM AUTHOR]