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Nowadays, bandwidth demand is enormously increasing, that causes the existing passive optical network (PON) to become the future optical access network. In this paper, next generation passive optical network 2 (NG-PON2) based, optical time division multiplexing passive optical network (OTDM-PON), wavelength division multiplexing passive optical network (WDM-PON) and time & wavelength division multiplexing passive optical network (TWDM-PON) systems with 20 Gbps (8 × 2.5 Gbps) downstream and 20 Gbps (8 × 2.5 Gbps) upstream capacity for eight optical network units has been proposed. The performance has been compared by varying the input power (−6 to 27 dBm) and transmission distance (10–130 km) in terms of -factor and optical received power in the presence of fiber noise and non-linearities. It has been observed that TWDM-PON outperforms OTDM-PON and WDM-PON for high input power and data rate (20/20 Gbps). Also, TWDM-PON shows its superiority for long-reach transmission up to 130 km, which is a cost-effective solution for future NG-PON2 applications.

Time-division multiplexing (TDM) is a mature scheme for the readout of arrays of transition-edge sensors (TESs). TDM is based on superconducting-quantum-interference-device (SQUID) current amplifiers. Multiple spectrometers based on gamma-ray and X-ray microcalorimeters have been operated with TDM readout, each at the scale of 200 sensors per spectrometer, as have several astronomical cameras with thousands of sub-mm or microwave bolometers. Here we present the details of two different versions of our TDM system designed to read out X-ray TESs. The first has been field-deployed in two 160-sensor (8 columns × 20 rows) spectrometers and four 240-sensor (8 columns × 30 rows) spectrometers. It has a three-SQUID-stage architecture, switches rows every 320 ns, and has total readout noise of 0.41  μ Φ 0 / √ Hz. The second, which is presently under development, has a two-SQUID-stage architecture, switches rows every 160 ns, and has total readout noise of 0.19  μ Φ 0 / √ Hz. Both quoted noise values are non-multiplexed and referred to the first-stage SQUID. In a demonstration of this new architecture, a multiplexed 1-column × 32-row array of NIST TESs achieved average energy resolution of 2.55 ± 0.01  eV at 6 keV.

The modern advancements have been made to form Next-Generation Ethernet Passive Optical Networks (NG-EPONs); it has been developed for handling the heavily bandwidth-demanding applications like HD video streaming, virtual/3D gaming, cloud computing-based applications, and virtual corporate working ecosystems. NG-EPON has been designed to provide ultra-high bandwidth with reliability and efficient resource management as compared to existing traditional Ethernet Passive Optical Network (EPON) systems. NG-EPON is basically a hybrid system that has been formed by collectively integrating time division multiplexing (TDM) and wavelength division multiplexing (WDM) features for effective data communication of future access networks. A hybrid system has been designed for the attainment of enhanced performance and cost efficacy. WDM-EPON system provides dedicated wavelength channels to the subscriber ONUs for high bandwidth, but with challenges of very high operational cost and channel underutilization. NG-EPON, as a hybrid system, mitigates the limitations by optimally allocating the wavelength channels and maintaining high performance in terms of bandwidth provision to bandwidth-hungry applications. The role of dynamic wavelength and bandwidth allocation (DWBA) algorithms for efficient bandwidth utilization in NG-EPON is our main point of concern in this study. To the best of our knowledge, the survey presented here is the first cohesive and up-to-date survey on the evolution towards NG-EPON. Novel contributions include the combination of DBA and DWBA algorithms in one framework and assessment of these combined algorithms within TDM-, WDM-, Hybrid-, and AI/ML-based categories. Additionally, this paper incorporates the discussion of machine learning, reinforcement learning, and federated learning based DBA approaches—topics rarely covered in prior works. Our study discusses and comparatively analyzes the different bandwidth utilization DWBA algorithms for NG-EPON. The study also examines time and wavelength division multiplexing strategies, addresses the challenges for DWBA, and provides us with the improved algorithms that have been designed and implemented in recent years. Additionally, the role of DWBA algorithms in improving bandwidth efficacy is analyzed, with a focus on QoS-aware algorithms. With NG-EPONs capable of delivering 25 Gbps per channel, these technologies play a crucial role in shaping future high-capacity optical access networks.

Fi-Wi networks, emblematic of the convergence between optical fibers and wireless access, stand resolutely at the vanguard of the transformative redefinition of communication paradigms. As advanced communication networks persistently redefine the contours of connectivity, characterized by their unparalleled speed, minimal latency, and augmented capacity, the exigency for innovative approaches undergoes heightened intensification. The crux of this study pivots upon the methodical application of multiplexing techniques, notably wavelength division multiplexing (WDM), optical code division multiplexing (OCDMA), and optical time division multiplexing (OTDM), each deployed with precision to elevate the nuanced performance of the Fi-Wi network. The multifaceted optimization of these techniques not only imparts an impetus to data transfer rates, mitigates latency, and augments spectral efficiency but concurrently instigates the realm of wireless connectivity. The research undertakes a technical exploration of the deployed multiplexing strategies, delineating their idiosyncratic advantages. A discerning comparative analysis vis-a-vis the hybrid (Fi-Wi)-single model, precisely serving as the baseline, unequivocally delineates the superior performance of the proposed methods across metrics of Q-factor, eye height, and logarithmic bit error rate-Q factor.

In this paper, three optical communication systems have been proposed to mitigate Four Wave Mixing (FWM). Three techniques are used, namely; low input power with high gain amplifier, a collective Optical Time Division Multiplexing (OTDM) and Dense Wavelength Division Multiplexing (DWDM) system, and the use of alternative circular polarization. The first technique involves reduction in input power to -20 dBm and then amplifying it 40 dB before demultiplexing. The second technique divides the input signal into four time slots and then combine them with a power combiner. In the third technique, the polarization of light coming from input channels is changed after modulation into right and left handed circular polarization. Exhaustive sets of simulations are performaed using Optisys. The performance analysis includes Q-factor, Optical Signal to Noise Ratio (OSNR), received optical power, minmum Bit Error Rate (BER) and eye diagram.

The CMB-S4 experiment is developing next-generation ground-based microwave telescopes to observe the cosmic microwave background with unprecedented sensitivity. This will require an order of magnitude increase in the 100-mK detector count, which, in turn, increases the demands on the readout system. The CMB-S4 readout will use time-division multiplexing (TDM), taking advantage of faster switches and amplifiers in order to achieve an increased multiplexing factor. To facilitate the design of the new readout system, we have developed a model that predicts the bandwidth and noise performance of this circuitry and its interconnections. This is then used to set requirements on individual components in order to meet the performance necessary for the full system. We present an overview of this model and compare the model results to the performance of both legacy and prototype readout hardware.

We are developing lab-based readout electronics for Transition-edge sensors (TES) using commercial-off-the-shelf (COTS) modules. These COTS modules are advantageous since they increase development speed and keep the cost low. We have developed these electronics to support both non-multiplexed and time-division multiplexing (TDM) readout systems. The system utilizes remote control via Ethernet, and the interface allows many types of measurements to be automated. With the TDM readout system, we have achieved 2.05 eV at 6 keV, 2.1 eV at 7 keV, 2.3 eV at 8 keV, and 2.8 eV at 12 keV with 2-column × 32-row multiplexing. We will be using this system in the characterization of detectors for the X-Ray Integral Field Unit (X-IFU) instrument on Athena. In this paper, we present an overview of the design and their performance.

Time-division multiplexing is the readout architecture of choice for many ground and space experiments, as it is a very mature technology with proven outstanding low-frequency noise stability, which represents a central challenge in multiplexing. Once fully populated, each of the two BICEP Array high-frequency receivers, observing at 150 GHz and 220/270 GHz, will have 7776 TES detectors tiled on the focal plane. The constraints set by these two receivers required a redesign of the warm readout electronics. The new version of the standard multichannel electronics, developed and built at the University of British Columbia, is presented here for the first time. BICEP Array operates time-division multiplexing readout technology to the limits of its capabilities in terms of multiplexing rate, noise and cross talk, and applies them in rigorously demanding scientific application requiring extreme noise performance and systematic error control. Future experiments like CMB-S4 plan to use TES bolometers with time-division/SQUID-based readout for an even larger number of detectors.

Electrode grids are used in neuroscience research and clinical practice to record electrical activity from the surface of the brain. However, existing passive electrocorticography (ECoG) technologies are unable to offer both high spatial resolution and wide cortical coverage, while ensuring a compact acquisition system. The electrode count and density are restricted by the fact that each electrode must be individually wired. This work presents an active micro‐electrocorticography (µECoG) implant that tackles this limitation by incorporating metal oxide thin‐film transistors (TFTs) into a flexible electrode array, allowing to address multiple electrodes through a single shared readout line. By combining the array with an incremental‐ΔΣ readout integrated circuit (ROIC), the system is capable of recording from up to 256 electrodes virtually simultaneously, thanks to the implemented 16:1 time‐division multiplexing scheme, offering lower noise levels than existing active µECoG arrays. In vivo validation is demonstrated acutely in mice by recording spontaneous activity and somatosensory evoked potentials over a cortical surface of ≈8×8 mm2. The proposed neural interface overcomes the wiring bottleneck limiting ECoG arrays, holding promise as a powerful tool for improved mapping of the cerebral cortex and as an enabling technology for future brain‐machine interfaces. Increasing electrode count of flexible electrode arrays in a sustainable way: Incorporating metal oxide thin‐film transistors into flexible micro‐electrocorticography (µECoG) electrode arrays enables multiplexing of the recording electrodes, overcoming the wiring bottleneck faced by current µECoG technologies. By combining the arrays with a dedicated silicon readout chip, 256 electrodes can be recorded simultaneously in time‐division multiplexing mode employing only 16 channels.

Single-photon lidar (SPL) exhibits high sensitivity, making it particularly suitable for detecting weak echoes over long distances. However, its susceptibility to background noise necessitates the implementation of advanced filtering techniques and complex algorithms, which can significantly increase system cost and complexity. To address these challenges, we propose a time-division-multiplexing-based correlated photon lidar system that employs a narrowband pulsed laser with stable time delays and variable pulse intensities, thereby establishing temporal and intensity correlations. This all-fiber solution not only simplifies the system architecture but also enhances operational efficiency. An adaptive cross-correlation method incorporating time slicing has been developed to extract histogram signals, enabling successful 1.5 km distance measurements under intense daytime noise conditions, using a 1 s accumulation time and a 20 mm receiving aperture. The experimental results demonstrate a 38% (from 1.11 to 1.52) improvement in the signal-to-noise ratio (SNR), thereby enhancing the system’s anti-noise capability, facilitating rapid detection, and reducing overall system costs.