Towards 10 Gb/s orthogonal frequency division multiplexing-based visible light communication using a GaN violet micro-LED

Visible light communication(VLC)is a promising solution to the increasing demands for wireless connectivity.Gallium nitride micro-sized light emitting diodes(micro-LEDs)are strong candidates for VLC due to their high bandwidths.Segmented violet micro-LEDs are reported in this work with electrical-to-optical bandwidths up to 655 MHz.An orthogonal frequency division multiplexing-based VLC system with adaptive bit and energy loading is demonstrated,and a data transmission rate of 11.95 Gb/s is achieved with a violet micro-LED,when the nonlinear distortion of the micro-LED is the dominant noise source of the VLC system.A record 7.91 Gb/s data transmission rate is reported below the forward error correction threshold using a single pixel of the segmented array when all the noise sources of the VLC system are present.

Flexible optoelectronic devices based on metal halide perovskites

The unique physical and chemical properties of metal halide perovskites predestine the devices to achieve high performance in optoelectronic field.Among the numerous high qualities of perovskites,their different low-temperature synthesis methods and preparation processes make them impressive and popular materials for flexible optoelectronic devices.Mainstream perovskite devices,for instance,solar cells,photodetectors and light-emitting diodes,have been fabricated on flexible substrates and show outstanding flexibility as well as high performance.For soft wearable electronic systems,mechanical flexibility is the premier condition.Compared to common devices based on rigid substrates,flexible perovskite devices are more practical and see widespread applications in energy,detection,display,and other fields.This review summarizes the recent progress of flexible perovskite solar cells,photodetectors and light-emitting diodes.The design and fabrication of different high-performance flexible perovskite devices are introduced.Various low-dimensional perovskite materials and configurations for flexible perovskite devices are presented.In addition,the limitations and challenges for further application are also briefly discussed.

Ultrafast Stretched-Pulse Fiber Laser Mode-Locked by Carbon Nanotubes

Ultrafast fiber sources having short pulses, broad bandwidth, high energy, and low amplitude fluctuations have widespread applications. Stretched-pulse fiber lasers, incorporating segments of normal and anomalous dispersion fibers, are a preferred means to generate such pulses. We realize a stretched-pulse fiber laser based on a nanotube saturable absorber, with 113 fs pulses, 33.5 nm spectral width and ~0.07% amplitude fluctuation, outperforming current nanotube-based designs.

Secure optical communication using a quantum alarm

Optical fibre networks are advancing rapidly to meet growing traffic demands.Security issues,including attack management,have become increasingly important for optical communication networks because of the vulnerabilities associated with tapping light from optical fibre links.Physical layer security often requires restricting access to channels and periodic inspections of link performance.In this paper,we report how quantum communication techniques can be utilized to detect a physical layer attack.We present an efficient method for monitoring the physical layer security of a high-data-rate classical optical communication network using a modulated continuous-variable quantum signal.We describe the theoretical and experimental underpinnings of this monitoring system and the monitoring accuracy for different monitored parameters.We analyse its performance for both unamplified and amplified optical links.The technique represents a novel approach for applying quantum signal processing to practical optical communication networks and compares well with classical monitoring methods.We conclude by discussing the challenges facing its practical application,its differences with respect to existing quantum key distribution methods,and its usage in future secure optical transport network planning.