Shiyi Xia

This paper presents an experimental investigation of a scalable, reconfigurable wavelength distribution node (WDN) architecture for next-generation optical metro-access networks, capable of dynamically routing coherent Wavelength Division Multiplexing (WDM) channels at multi-Tbps levels, with 800 Gbps per channel. The proposed architecture leverages novel photonic integrated erbium-doped waveguide amplifiers (EDWAs) combined with Semiconductor Optical Amplifier (SOA)-based 1×N Wavelength Selective Switches (WSS), facilitating dynamic add/drop capabilities essential for flexible metro-access deployments. Three experiments validated the architecture’s transmission performance and scalability. The first experiment demonstrated successful add/drop and drop&continue dynamic switching of six 800 Gbps WDM channels, achieving an aggregate throughput of 4.8 Tbps with an average Optical Signal-to-Noise Ratio (OSNR) degradation of only 0.55 dB after one node, and 2.4 dB after cascading two nodes over a 55.2 km link. The second experiment confirmed error-free transmission of eight 800 Gbps WDM channels, recording a maximum OSNR penalty variation among channels of 3.56 dB. The third experiment evaluated scalability using a 1×4 for WDN1, 1×16 WSS for WDN2 configuration, achieving error-free transmission serving up to 64 access points at 800 Gbps per channel, with a cumulative OSNR penalty of 7.44 dB after cascading two WDN nodes. These results demonstrate the feasibility and high performance of integrated photonic solutions in meeting future 6G network demands.

By introducing the arrayed waveguide router (AWGR) optical true time-delay (OTTD) architecture in bent-pipe satellite optical inter-link to optically assist the RF phased array in Low-earth orbit satellites will extend the multi-hop bent-pipe satellite beam-hopping protocol proposed in DVB-S2X. It solves the challenge of beam steering with the support of precise, broadband, and wide-range scanning. This architecture utilizes a subarray to combine the advantages of AWGR and a high-precision RF phase shifter to realize the beam pointing without an oblique view. Unlike the traditional digital and analog phased array architecture, the introduction of OTTD can solve the problem of beam squint and also ensure the high-precision scanning of the beam.

As the number of non-geostationary orbit (NGSO) satellites continues to grow, interference with other communication systems, including radio astronomy systems (RASs), is becoming increasingly critical. In this study, an interference simulation framework was developed to analyse the potential impact of NGSO systems on RAS in accordance with the relevant International Telecommunication Union (ITU) regulations and recommendations. In addition to the simulation of interference generated by individual NGSO satellite systems, the framework also supports the analysis of aggregate interference from multiple NGSO satellite systems. By inputting satellite system parameters, including constellation configuration, user distribution and beam scheduling strategy, the framework is able to obtain interference probability distributions for a typical RAS ground station at different latitudes and observation directions. The simulation results provide a reference for the analysis of interference from NGSO satellite systems to RASs, and can also be used to guide the development of strategies to mitigate harmful interference to RASs.

Laser diodes (LDs) are used in a wide range of applications, such as optical wireless communications and LIDAR. To meet the demanding requirements of LDs for high accuracy and stability of the injection current, a high-precision, high stability LD driver with overvoltage protection is proposed. A novel structure based on enhanced Howland current source is described: composite topology enhanced Howland current source (CTEHCS), which has the advantages of high precision, high stability, and extensive regulation range. A 20-bit DAC and high-precision reference source are used to form a front-stage DAC circuit for precise and stable voltage reference. A closed-loop feedback calibration loop is applied to eliminate significantly the absolute errors and auxiliary calibrating of the effect of power operational amplifier on the temperature rise of critical devices. An innovative overvoltage protection circuit is designed for the load side of the CTEHCS, and the protection range can be flexibly set to 4/5/6 V to avoid damage to loads such as LDs. The noise performance, accuracy and stability, modulation bandwidth, nonlinear error, overvoltage protection performance, and turn-on and turn-off time of the experimental prototype are described in detail.

In the above article [1] , the authors inadvertently did not include the affiliation of the first author. The name of the organization is “University of Chinese Academy of Sciences.”