Photodetectors hold a critical position in optoelectronic integrated circuits, and they convert light into electricity. Over the past decades, high‐performance photodetectors (PDs) have been aggressively pursued to enable high‐speed, large‐bandwidth, and low‐noise communication applications. Various material systems have been explored and different structures designed to improve photodetection capability as well as compatibility with CMOS circuits. In this paper, we review state‐of‐theart photodetection technologies in the telecommunications spectrum based on different material systems, including traditional semiconductors such as InGaAs, Si, Ge and HgCdTe, as well as recently developed systems such as low‐dimensional materials (e.g. graphene, carbon nanotube, etc.) and noble metal plasmons. The corresponding material properties, fundamental mechanisms, fabrication, theoretical modelling and performance of the typical PDs are presented, including the emerging directions and perspectives of the PDs for optoelectronic integration applications are discussed.

Inspired by biological diversity and uniqueness, the concept of bionic optical physical unclonable functions (PUFs) is proposed. Production is simple, low-cost, green and environmentally friendly. The extracted binary codes from bionic PUFs are random, unclonable, and robust enough for applications in entity authentication and encrypted communication.

A high permittivity dielectric gives the impression of outperforming plasmonic noble metal in visible light fluorescence enhancement primarily because of its small loss. Nonetheless, the performances of these two platforms in various situations remain obscure due to the different optical confinement mechanisms as well as the complexity in the fluorescence enhancement process. This study presents a comprehensive comparison between these two platforms based on nanoparticles (NPs) to evaluate their capability and applicability in fluorescence enhancement by taking into account the fluorescence excitation rate, the quantum yield, the fluorophore wavelengths and Stokes shifts as well as the far field intensity. In a low permittivity sensing medium (e.g. air), the dielectric NP can achieve comparable or higher fluorescence enhancement than the metal NP due to its decent NP-enhanced excitation rate and larger quantum yield. In a relatively high permittivity sensing medium (e.g. water), however, there is a significant decrement of the excitation rate of the dielectric NP as the permittivity contrast decreases, leading to a smaller fluorescence enhancement compared to the metallic counterpart. Combining the fluorescence enhancement and the far field intensity studies, we further conclude that for both dielectric and plasmonic NPs, the optimal situation occurs when the fluorescence excitation wavelength, the fluorescence emission wavelength and the electric-dipole-mode of the dielectric NP (or the plasmonic resonance of the metal NP) are the same and all fall in the low conductivity region of the NP material. We also find that the electric-dipole-mode of the dielectric NP performs better than the magnetic-dipole-mode for fluorescence enhancement applications because only the electric-dipole-mode can be strongly excited by the routinely used fluorescent dyes and quantum dots, which behave as electric dipoles by nature.