Modularized orthogonal-polarization dual-wavelength microcavity based on light curing gradient-composite multi-dimensional meta-filters

The utilization of a stable orthogonally polarized laser can promote the head-mounted miniature fluorescence microscopy into a powerful tool for real-time intracerebral three-dimensional observation. However, the realization of wearable dual-wavelength polarized light sources has remained an attractive challenge to break through the spatial constraints of transmitting fiber-optic paths. Herein, we have proposed a modularized orthogonal-polarization dual-wavelength microcavity enabled by high reflectance (HR) and output-coupled (OC) gradient-composite multi-dimensional meta-filters, where these printable meta-filters are composed of two nanocomposite metasurfaces (NCMSs). Specifically, based on the Mie surface lattice resonances (Mie-SLR), the designed NCMSs can realize tunable multi-parameter filtering at diverse dimensions (wavelength, polarization, and incident angle) by optimizing the lattice distances. By virtue of the sandwich-type gradient-composite configuration, the proposed meta-filters have integrated orthogonal-polarization filtering of two independent NCMS at 1064 nm and 1320 nm. The stability of the multi-dimensional filtering capabilities of the proposed meta-filters has been enhanced by optimizing the thickness of the resin bonding layers in the gradient-composite structure. Without other nonlinear modulation, orthogonal-polarization dual-wavelength mode oscillations can be developed only by passive multi-dimensional filtering of HR and OC meta-filters in the microcavity. These proposed new-generation gradient-composite multi-dimensional meta-filters will provide novel strategies toward high-robust miniature light sources for wearable optical devices.