No abstract

2D materials exhibit superior properties in electronic and optoelectronic fields. The wide demand for high‐performance optoelectronic devices promotes the exploration of diversified 2D materials. Recently, 2D covalent organic frameworks (COFs) have emerged as next‐generation layered materials with predesigned π‐electronic skeletons and highly ordered topological structures, which are promising for tailoring their optoelectronic properties. However, COFs are usually produced as solid powders due to anisotropic growth, making them unreliable to integrate into devices. Here, by selecting tetraphenylethylene monomers with photoelectric activity, elaborately designed photosensitive 2D‐COFs with highly ordered donor‐acceptor topologies are in situ synthesized on graphene, ultimately forming COF‐graphene heterostructures. Ultrasensitive photodetectors are successfully fabricated with the COFETBC–TAPT‐graphene heterostructure and exhibited an excellent overall performance with a photoresponsivity of ≈3.2 × 107 A W−1 at 473 nm and a time response of ≈1.14 ms. Moreover, due to the high surface area and the polarity selectivity of COFs, the photosensing properties of the photodetectors can be reversibly regulated by specific target molecules. The research provides new strategies for building advanced functional devices with programmable material structures and diversified regulation methods, paving the way for a generation of high‐performance applications in optoelectronics and many other fields.

We present an ultra-small all-silica high temperature sensor based on a reflective Fabry-Perot modal interferometer (FPMI). Our FPMI is made of a micro-cavity (approximately 4.4 microm) directly fabricated into a fiber taper probe less than 10 mum in diameter. Its sensing head is a miniaturized single mode-multimode fiber configuration without splicing. The sensing mechanism of FPMI is the interference among reflected fundamental mode and excited high-order modes at the end-faces. Its temperature sensitivity is approximately 20 pm/degrees C near the wavelength of 1550 nm. This kind of sensor can work in harsh environments with ultra-large temperature gradient, but takes up little space because of its unique geometry and small size.

Liquid-crystal fork gratings are demonstrated through photopatterning realized on a DMD-based microlithography system. This supplies a new strategy for generating fast switchable, reconfigurable, wavelength-tolerant and polarization-insensitive optical vortices. The technique has great potential in broad fields such as OAM-based quantum computations, optical communications, and micromanipulation.