Polarized Laser Switching with Giant Contrast in MOF‐Based Mixed‐Matrix Membrane

Nonlinear optical (NLO) switch materials have attracted considerable attention in photonics. Although various materials based on complex structural transitions have been developed extensively, the studies on light‐driven up‐conversion laser switches are rare, which have advantages including easy operations at room temperature and high contrasts. Here, the concept of photoswitch building unit is proposed to construct a novel sandwich‐like mixed‐matrix membrane. Dye@metal‐organic framework (MOF) crystals and spirooxazine are regarded as the laser emission and absorption units, followed by their hierarchical encapsulation into the polydimethylsiloxane carrier unit. Excited MOF microcrystals exhibit two‐photon pumped lasing anisotropy, with an ultrahigh degree of linear polarization (≈99.9%). Photochromic molecules can be interconverted by the external ultraviolet stimulus, causing sharp absorption‐band variations and inducing the laser emission or quenching. Such up‐conversion polarized laser switch material is reported for the first time. Record‐high NLO contrast (≈6.1 × 10(4)) among the solid‐state NLO switch materials can be obtained through simultaneously controlling the ultraviolet irradiation and the emission‐detected polarization direction at room temperature.