Locally addressable nanophotonic devices are essential for modern applications such as light detection, optical imaging, beam steering and displays. Despite recent advances, a versatile solution with a high-speed tuning rate, long-life durability and programmability across multiple pixels remains elusive. Here we introduce a programmable nanophotonic matrix consisting of vanadium dioxide (VO₂) cavities on pixelated microheaters that meets all these requirements. The indirect Joule heating of these VO₂ cavities can result in pronounced spectral modulation with colour changes and ensures exceptional endurance even after a million switching cycles. Precise control over the thermal dissipation power through a SiO₂ layer of an optimized thickness on Si facilitates an ultrafast modulation rate exceeding 70 kHz. We demonstrated a video-rate nanophotonic colour display by electrically addressing a matrix of 12 × 12 pixels. Furthermore, inspired by the unique pixel-level programmability with multiple intermediate states of the spectral pixels, a spatiotemporal modulation concept is introduced for spectrum detection.

Cellulose nanocrystals produced by acid hydrolysis of native cellulose form a well-known chiral nematic liquid crystal phase. The mechanism involved in the formation of chirality has been the subject of a vigorous discussion. The pH and concentration dependence of the phase is studied using cellulose nanocrystal droplets within a silicon oil suspension, which allows for convenient real-time microscale manipulation of phase behaviors and properties. We demonstrate the existence of nematic phases at both low and high pH regions consistent with the Stroobants - Lekkerkerker - Odijk theory. Our results confirm electrostatic interactions play a critical role in controlling the strength of the chirality.

A silicon-based microdonut resonator consisting of a multimode microdonut waveguide is realized. The random shift of the resonance wavelength due to the fabrication deviation is greatly reduced to be ~0.91 nm compared with that (~4.93 nm) of those regular microring resonators (on the same chip). For the coupling between the access waveguide and the microdonut waveguide, bent directional couplers are used to suppress the undesired higher-order modes according to the phase-matching condition. A local laser-trimming process with a ~1.1-W blue laser is further applied and can introduce a maximal wavelength shift of ~0.46 nm for the resonance alignment. This letter combines the present microdonut resonator design technique and the local laser-trimming process, which potentially provides a promising approach to realize a micro-resonator array with excellent resonance-wavelength alignment.

We demonstrate an improved approach to integrate various color filters on a chip-scale by using stepwise metal-insulator-metal FP cavities. The cavity is composed of a thick silver mirror, an SU8 gap layer of controlled thickness, and a thin nickel layer. Reflective colors from red to blue can be generated from these filters through a simple UV lithography process. The filters were also fabricated on a flexible substrate which could be incorporated into wearable devices. This method can realize large-scale filter arrays with simple processing and may facilitate the use of structural color filters in displays and sensing.

Structural color filters based on all-dielectric materials are considered to be promising alternatives to metal nanostructures due to significant advantages, such as high-quality resonance effects and low losses of Ohmic effects. We demonstrate a polarization tunable color filter based on all-dielectric metasurfaces, which is based on the arrays of asymmetric monocrystalline silicon nanoblocks on the flexible substrate. By adjusting the physical dimensions of nanoblocks, the filter can exhibit a variety of bright transmission colors. Furthermore, the designed dielectric metasurfaces are sensitive to the linear polarization direction of the incident light, thus a wide range of color images can be created by changing the polarization angles. All of the color filter including the dielectric silicon nanoblocks, the overcladding, and the flexible substrate can be delaminated from the handler substrates and the optical property is reconfigurable, which will find applications in the functional color display, polarization detection and imaging, and secured optical tag.

In this paper, we show that the guided mode resonance can exist in a low-index waveguide layer on top of a high-index substrate. With the help of the interaction of diffraction from a metal grating and total internal reflection effects, we verify that the guided mode can be supported in the low-index SU8 layer on a high-index substrate. Simulation and experiment show the resonant wavelength can be simply manipulated by controlling the geometrical parameters of the metal grating and waveguide layer. This structure extends the possibilities of guided-mode resonance to a broader class of functional materials and may boost its use in applications such as field enhancement, sensing and display.