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Polarization images offer crucial functionalities across multiple scientific domains, providing access to physical information beyond conventional measures such as intensity, phase, and spectrum of light. However, the challenge of transmitting polarization images through complex media has restricted their application in optical communication and imaging. Here, a novel approach utilizing deep learning for the transmission of full‐Stokes polarization images through scattering media is presented. It is demonstrated that any input polarization image can be reconstructed in a single shot by employing only an intensity sensor. By supervised training of a deep neural network, high‐accuracy full‐Stokes reconstruction is achieved from the speckle pattern detected by an intensity camera. Leveraging the deep learning based polarization decoder, a polarization‐colored encoding scheme is devised to enable increased‐capacity data transmission through disordered channels. Fast, wavelength‐independent, on‐chip, polarization imaging in complex media enables the utilization of polarization‐structured light in multimode fibres and opaque materials, unlocking new possibilities in optical communication, cryptography, and quantum technology. [ABSTRACT FROM AUTHOR]

Heterojunction phototransistor (HPT) is considered the most promising detector technology in weak ultraviolet (UV) signal detection due to its inherent internal gain through transistor action. However, achieving high‐performance self‐powered UV HPTs remains a significant challenge. In this study, a high‐performance self‐powered p+‐GaN/n−‐ZnO/Au UV HPT with ZnO serving as the floating base is cleverly designed. The device features a unique back‐to‐back configuration of the p+‐GaN/n−‐ZnO heterojunction and n−‐ZnO/Au Schottky junction, along with an ultrathin ZnO base layer of a 3D nanowire network structure. This design enables the fabricated p+‐GaN/n−‐ZnO/Au UV HPT to operate in a self‐powered mode with exceptional performance metrics. Under zero bias, the device exhibits outstanding characteristics including ultralow dark current of 1.7 × 10−13 A, remarkable Iphoto/Idark ratio of 106, fast response speed (tr = 150 µs / tf = 250 µs), high responsivity of 9.74 A W−1, and detectivity of 1.58 × 1014 Jones, representing the best result achieved for UV HPTs thus far at zero bias. Moreover, the fabricated UV HPT is successfully demonstrated in solar‐blind imaging and UV communication systems without the need for an external power supply. This work presents effective and practical design strategies for achieving high‐performance self‐powered UV HPTs. [ABSTRACT FROM AUTHOR]

This study investigates the integration of dimmable constant weight polar‐coded non‐orthogonal multiple access (NOMA) with orthogonal space‐time block coding (OSTBC) in visible light communication (VLC) systems over Nakagami‐m$m$ fading environments. The proposed scheme aims to enhance the reliability of VLC systems by reducing the outage probability while accommodating dimming requirements. By allowing multiple users to utilize the same time‐frequency resources and adjust power levels based on individual channel conditions, the system optimizes resource utilization. Additionally, the OSTBC method provides effective communication among multiple users by leveraging transmit diversity to improve system performance. The efficacy of the proposed approach is demonstrated through analytical analysis and Monte Carlo simulations, showcasing superior outage probability performance compared to conventional Alamouti‐STBC schemes. [ABSTRACT FROM AUTHOR]

This study analyses the interference effect in a visible light‐non‐orthogonal multiple access (VL‐NOMA) network that considers the signal power parameters performance for near and far users. The light‐emitting diode (LED) as a carrier transmits signals, and we investigate the interference effect. The interference effect challenge is a result of unaligned signal power parameters, thereby producing noise or echo during the signal transmission. The signal power parameters are successfully aligned, and NOMA techniques are deployed, which improves the signal performance in terms of bit‐error rate (BER), achieved data rate, and signal‐to‐interference plus noise ratio (SINR). Furthermore, the deployed NOMA techniques, such as power allocations (PA) to assign the signals appropriately, then superposition coding (SC) encodes the entire signal, and successive interference cancellation (SIC) cancels the interference within the signals. The signal behavior of the aligned and the unaligned signal power parameters performance are used to investigate the interference effect. We observed that unaligned signal power parameters reduce the signal performance of achieved data rate, BER, and SINR. Further, the aligned signal power parameter with NOMA techniques improves the signal performance. Moreover, in the aligned signal power scenario of NOMA, the near user performed better than the far user. [ABSTRACT FROM AUTHOR]

A coherent optical receiver digital signal processing (DSP) scheme is proposed based on spectral clustering, which utilises spectral clustering to cluster the signals outputted by the DSP. Compared to existing blind DSP algorithms for coherent optical receivers operating at over 100Gbps with PM‐mQAM, the proposed scheme effectively suppresses various physical impairments, achieving lower bit error rates (BERs) at the same transmission distance, thus enabling longer transmission distances under the same forward error correction threshold. Furthermore, simulations of the proposed scheme on a 14GBaud PM‐16QAM coherent optical transmission system show that, at a BER of 1.9E‐2, the maximum transmission distance increases from 1700 to 2000 km, and at a BER of 3.8E‐3, it increases from 700 to 900 km. [ABSTRACT FROM AUTHOR]

Free space optical (FSO) communication has shown promising advantages among other wireless schemes. It provides a very high data rate, freedom from licensing, low cost of deployment and requires low power. FSO is a technology that has undergone rapid development over the last several years. These communication systems are a line-of-sight technology in which information is transmitted through the atmosphere on modulated laser beams or light-emitting diode (LED) beams. When FSO technology was first introduced, it was seen as an attractive option to bridge the "last mile bottleneck" that is present in many of today's optical fiber-based networks. As compared to existing radio frequency (RF) based wireless systems, this technology possesses multiple advantages, such as high bandwidth, license-free band use, long operational range, spatial reusability, security and immunity to electromagnetic interference. The narrow and directional characteristics of a laser beam employed in FSO enable spatial reuse and make it hard to eavesdrop, thus raising the level of security. The use of light as carrier in this technology provides immunity to electromagnetic interference. Despite its many advantages, this technology is susceptible to some weather conditions, such as fog, rain, sleet and snow, and to misalignment of transmitter–receiver terminals. Atmospheric conditions will impair the propagation of an optical signal because the propagation of light may undergo absorption and scattering. Pointing error caused by misalignment of the transceivers is another major challenge in FSO communication system. The pointing error may result in degradation or even total loss of the received signal. This error may arise because of transceiver sway, platform vibration, the motion of mobile stations, errors or uncertainties in the tracking system. Another type of pointing error is beam wandering caused by the in-homogeneity of large-scale eddies in the atmosphere (i.e., atmospheric turbulence), where the transmitted beam may deviate from its intended path. This survey paper focuses on the systems involved in the alignment of the transmitter and the receiver so that the maximum amount of power is collected by the receiver and the analysis of beam profile in various atmospheric conditions and their mitigation methods. [ABSTRACT FROM AUTHOR]

The demand for miniaturized and integrated multifunctional devices drives the progression of high‐performance infrared photodetectors for diverse applications, including remote sensing, air defense, and communications, among others. Nonetheless, infrared photodetectors that rely solely on single low‐dimensional materials often face challenges due to the limited absorption cross‐section and suboptimal carrier mobility, which can impair sensitivity and prolong response times. Here, through experimental validation is demonstrated, precise control over energy band alignment in a type‐II van der Waals heterojunction, comprising vertically stacked 2D Ta2NiSe5 and the topological insulator Bi2Se3, where the configuration enables polarization‐sensitive, wide‐spectral‐range photodetection. Experimental evaluations at room temperature reveal that the device exhibits a self‐powered responsivity of 0.48 A·W−1, a specific directivity of 3.8 × 1011 cm·Hz1/2·W−1, a response time of 151 µs, and a polarization ratio of 2.83. The stable and rapid photoresponse of the device underpins the utility in infrared‐coded communication and dual‐channel imaging, showing the substantial potential of the detector. These findings articulate a systematic approach to developing miniaturized, multifunctional room‐temperature infrared detectors with superior performance metrics and enhanced capabilities for multi‐information acquisition. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper uses numerical investigation to present an efficient photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor. The proposed sensor is simulated and modelled by the finite element method (FEM). The plasmonic and analyte layers are utilized on the fiber's exterior to ease practical implementation. Additionally, the designed sensor contains all the circular air holes, making it simpler and easier to fabricate using currently available techniques. Silver (Ag) and tantalum pentaoxide (Ta2O5) are used as plasmonic materials for surface plasmon generations and to achieve smooth coupling. The sensor achieves the maximum wavelength sensitivity of 22860 nm/RIU and amplitude sensitivity of 1758 1/RIU. Moreover, the sensor shows a wide refractive range of chemical sensing capabilities within 1.375-1.400. Due to the broad RI detection range, the proposed sensor can detect various biological cells, biochemicals, and food additives, making this sensor applicable in medical applications and food quality control. [ABSTRACT FROM AUTHOR]

Abstract A coherent optical receiver digital signal processing (DSP) scheme is proposed based on spectral clustering, which utilises spectral clustering to cluster the signals outputted by the DSP. Compared to existing blind DSP algorithms for coherent optical receivers operating at over 100Gbps with PM‐mQAM, the proposed scheme effectively suppresses various physical impairments, achieving lower bit error rates (BERs) at the same transmission distance, thus enabling longer transmission distances under the same forward error correction threshold. Furthermore, simulations of the proposed scheme on a 14GBaud PM‐16QAM coherent optical transmission system show that, at a BER of 1.9E‐2, the maximum transmission distance increases from 1700 to 2000 km, and at a BER of 3.8E‐3, it increases from 700 to 900 km.

Abstract This study analyses the interference effect in a visible light‐non‐orthogonal multiple access (VL‐NOMA) network that considers the signal power parameters performance for near and far users. The light‐emitting diode (LED) as a carrier transmits signals, and we investigate the interference effect. The interference effect challenge is a result of unaligned signal power parameters, thereby producing noise or echo during the signal transmission. The signal power parameters are successfully aligned, and NOMA techniques are deployed, which improves the signal performance in terms of bit‐error rate (BER), achieved data rate, and signal‐to‐interference plus noise ratio (SINR). Furthermore, the deployed NOMA techniques, such as power allocations (PA) to assign the signals appropriately, then superposition coding (SC) encodes the entire signal, and successive interference cancellation (SIC) cancels the interference within the signals. The signal behavior of the aligned and the unaligned signal power parameters performance are used to investigate the interference effect. We observed that unaligned signal power parameters reduce the signal performance of achieved data rate, BER, and SINR. Further, the aligned signal power parameter with NOMA techniques improves the signal performance. Moreover, in the aligned signal power scenario of NOMA, the near user performed better than the far user.

Abstract This study investigates the integration of dimmable constant weight polar‐coded non‐orthogonal multiple access (NOMA) with orthogonal space‐time block coding (OSTBC) in visible light communication (VLC) systems over Nakagami‐m fading environments. The proposed scheme aims to enhance the reliability of VLC systems by reducing the outage probability while accommodating dimming requirements. By allowing multiple users to utilize the same time‐frequency resources and adjust power levels based on individual channel conditions, the system optimizes resource utilization. Additionally, the OSTBC method provides effective communication among multiple users by leveraging transmit diversity to improve system performance. The efficacy of the proposed approach is demonstrated through analytical analysis and Monte Carlo simulations, showcasing superior outage probability performance compared to conventional Alamouti‐STBC schemes.

Abstract Solar cells are increasingly being utilised for both energy harvesting and reception in free‐space optical (FSO) communication networks. The authors focus on the implementation of a mid‐band p‐In0.01Ga0.99 N/p‐In0.5Ga0.5 N/n‐In0.5Ga0.5 N (PPN) solar cell, boasting an impressive 26.36% conversion efficiency (under 1.5AM conditions) as a receiver within an indoor FSO communication network. Employing a solar cell with dimensions of 1 mm in length and width, the FSO system underwent simulation using Optisystm software, while the solar cell's behaviour was simulated using SCAPS‐1D. The received power from the solar cell was then compared to that of four commercially available avalanche photodiode (APD) receivers. Exploring incident wavelengths spanning 400–700 nm within the visible spectrum, across transmission distances of 5, 10, 15, and 20 m, the study presented current‐voltage (IV) and power‐voltage curves. Notably, the InGaN solar cell exhibited superior electrical power output compared to all commercial APDs. In conclusion, the findings underscore that augmenting received power has the potential to enhance FSO network quality and support extended transmission distances.

【Objective】In this paper, an ultra-low power consumption optical transmitter is developed to broaden the application of optical communication in short-reach interconnection such as board level and backplane level. The basic principle of the scheme is that the Vertical-Cavity Surface-Emitting Laser (VCSEL) laser generates an optical pulse signal after loading a bias current and a modulation signal through a Bias-T circuit.【Methods】In this work, the feasibility of the scheme is verified by means of simulation. It is also found that the main factors affecting the increase of the transmission rate are the parasitic parameters of the laser device and the impedance matching of the drive circuit. The two electrical transmission distances of 200 and 10 mm are studied by experiments. And the law of eye diagram quality and bit error rate as a function of driving voltage and bias current is studied through experiments under two electrical transmission distances.【Results】The results show that a larger effective extinction ratio ranging from 0.84 to 6.69 dB can be obtained by shortening the electrical transmission distance to 10 mm with the minimum differential driving voltage of 200 mV, the minimum bias current of 15 mA, and the power consumption of 1.2 mW/Gbit/s. Compared with traditional optical modules, the power consumption of optical transmission is reduced by about 80%.【Conclusion】This optical transmitter solution can be applied to intra-data center. Combined with low-power optical receivers, the overall power consumption of the data center can be significantly reduced.

Benefiting from the discovery of novel organic semiconductor materials bearing tunable absorption characteristics, narrowband organic photodetectors (OPDs) with improved performance are reported. Alongside new photoactive materials synthesis, several device engineering strategies are introduced to achieve narrowband OPDs, allowing less dependence of the device performance on the synthetic variation control, such as batch‐to‐batch differences in molecular weight. However, fabrication of multiband OPDs remains a challenge. Current solutions are usually based on vertical multi‐stacking of photosensitive layers with different absorption spectra and voltage‐modulated charge collection/injection, which renders the device fabrication too complex, while their response speed and band selectivity is limited. In this work, the concept of optical cavity is adopted to demonstrate self‐powered and fast response speed single‐junction bidirectional organic photodetectors with dual narrowband detection in the ultraviolet (UV) and visible part of the spectrum. Application of these devices in encrypted UV communication is successfully demonstrated. A third band in the near infrared (NIR) is possible to be isolated, rendering these high‐performing and simple to manufacture multiband OPD devices attractive for high‐resolution imaging and optical wireless communication. [ABSTRACT FROM AUTHOR]

Broadband near‐infrared (NIR) phosphors are crucial components of next‐generation NIR lighting sources. However, the design of high‐efficiency and thermally stable NIR phosphors still poses a significant challenge, whose quantum efficiencies (QEs) are directly limited by their absorption efficiency (AE) toward incident light. Here, an efficient and thermally stable NIR emission with AE up to 64.9% and emission keeping of 91.23% at 423 K is demonstrated via Cr3+ heavy solid solution in rigid framework LiCaGaF6:Cr3+ (LCGFC). Isomorphic LiCaAlF6:Cr3+ also exhibits thermal robustness, while traps in low doping concentration and low QEs. Comparative studies on crystal structure, formation energy, and Helmholtz free energy disclose that Cr3+ substitution on equivalent and equiradius Ga3+ site versus radii differential Al3+ site generates heavier solid solution and sustainable structural rigidity with acquirement of higher AE and better thermal stability. Incorporating LCGFC with a blue InGaN chip, a NIR phosphor‐converted light‐emitting diode is fabricated to realize stable wireless optical communication with good penetrability through biological tissue and some organic products. These findings develop a strategy based on activator heavy solid solutions in a rigid framework to achieve high‐efficiency and thermally stable NIR phosphors but also advance their novel optoelectronic applications. [ABSTRACT FROM AUTHOR]

To increase the accuracy of indoor visible light positioning, a novel indoor visible light localization technique based on the marine predator algorithm-optimized least squares support vector machine (MPA-LSSVM) is suggested. The light signals of each reference point are recorded in the first place and a fingerprint database is created. Introduced thereafter is the marine predator algorithm, which, through iterative optimization of the hyperparameters of the least squares support vector machine, aims to establish an optimal localization model using finely-tuned hyperparameters. This culminated in the development of a positioning model, successfully attaining the objective of enhancing accuracy in positioning while minimizing time expenditure. In an indoor-positioning scene (size: 1 m × 1 m × 1 m), the average positioning error of the proposed positioning method is 0.041 m, and the proportion of test points with positioning errors less than 0.1 m is 96.7%. [ABSTRACT FROM AUTHOR]

The traditional base station in C-RAN is divided into three parts: a pool of centralized baseband units (BBUs), a fronthaul network that links the BBUs and remote radio units (RRUs), and RRUs. This paper proposes a novel cooperative algorithm for resource optimization in a time-wavelength division multiplexed (TWDM) passive optical network (PON) incorporating a cloud radio access network (C-RAN). First, a joint collaborative strategy is deployed to optimize cooperative caching and transmission in the wireless and optical domains. Then, the quality of experience (QoE) is improved by bandwidth configuration and caching. Simulation results show that the average throughput of the proposed QoE-aware video cooperative caching and transmission mechanism (QACCTM) algorithm is approximately 30% higher than that of other algorithms. Compared with the relative average residual clutter power (RARCP) and quality-aware wireless edge caching (QAWEC) algorithms, the proposed QACCTM algorithm reduces the access delay by approximately 27.1% and 15.9%, respectively. [ABSTRACT FROM AUTHOR]

The progressive downscaling of silicon‐based microelectronic devices delivers compact and advanced integrated circuits for fast data processing and computing. Similarly, the miniaturization of conventional optoelectronics is also an important frontier of technology for emerging lighting, imaging, communication, and sensing. Herein, this study reports a miniature dual‐functional diode (DF‐diode) with both light‐emitting and light‐detecting functionalities. The proposed micro‐scale DF‐diode exhibits a record high responsivity of 300 mA W−1 at 265 nm with an ultrafast response rise time of 3.7 ns in light‐detecting mode. While operating in emitting mode, it demonstrates an extraordinarily high −3 dB optical bandwidth above 585 MHz with an enhanced external quantum efficiency performance. Significantly, the development of micro‐scale DF‐diodes has opened up a new avenue toward the realization of an effective and long‐distance solar‐blind optical communication system in the future. [ABSTRACT FROM AUTHOR]

Light‐emitting diodes and photodiodes, often acting as transmitters and receivers, are two key optical components for constructing an optical communication system. Recently, solar‐blind optical wireless communication (SB‐OWC) has emerged as a promising free‐space communication platform due to its unique advantages, including low background noise, high security, and non‐line‐of‐sight ability. However, the development of deep ultraviolet (DUV) emitters and detectors is still in its early stages with relatively low efficiency and poor detection capability, which hampers the further progress of SB‐OWC. Herein, a triangular‐shaped micro‐sized diode (T‐μ‐diode) is reported that can significantly boost its DUV emission and detection performance compared with a regular circular‐shaped micro‐diode (C‐μ‐diode) due to improved current injection and enhanced light extraction/absorption behavior. Specifically, the T‐μ‐diodes demonstrate superior light output power with a −3 dB modulation bandwidth over 566 MHz operating at an extremely high current density of 2 kA cm−2 while possessing a higher photo‐responsivity of ≈160 mA W−1 with a faster response speed of 5.1 ns, surpassing the traditional C‐μ‐diodes in both light emitting and detecting modes. Importantly, a bidirectional on‐chip data transmission system is realized by simply switching the operation mode of two T‐μ‐diodes monolithically fabricated on the same platform with boosted emission and detection functionalities. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to optical communication systems by introducing a hybrid MGDM–FSO (Mode Group Diversity Multiplexing—Free Space Optical) system. The primary objective of this innovative system is to address the limitations of traditional communication systems, particularly in challenging environmental conditions. By combining the advantages of MGDM, which enhances transmission capacity in optical fibers, with the flexibility and high data rates offered by FSO technology, the hybrid MGDM–FSO system aims to overcome obstacles encountered during data transmission. In this study, we provide a detailed analysis of the proposed system's architecture and performance characteristics under various operating conditions. Specifically, we investigate both single-input single-output (SISO) and multiple-input multiple-output (MIMO) configurations of the MGDM–FSO system. Performance metrics such as received power levels, bit error rate (BER), and quality factor (Q-factor) are evaluated to assess the system's efficiency across different weather conditions. Numerical simulations are conducted to analyze the system's performance under a range of scenarios. Our findings indicate that under clear weather conditions, both SISO and MIMO configurations exhibit optimal performance, characterized by high Q-factor and low BER. However, as weather conditions deteriorate to heavy rain and heavy fog, the Q-factor of the received signal decreases, highlighting the impact of environmental factors on system performance. This study contributes valuable insights into the behavior of hybrid MGDM–FSO systems and emphasizes the importance of robust communication techniques to mitigate environmental challenges. The findings presented here have implications for the design and implementation of optical communication systems in real-world scenarios. [ABSTRACT FROM AUTHOR]

This paper simulated the operation of vacuum state and single decoy state protocols in the BB84 and SARG04 QKD schemes by utilizing the features of the commercial ID-3000 QKD system. Numerical modeling identified an optimal signal-to-decoy state ratio of 0.95:0.05 and an intensity of μ=0.85 for the signal state and ν1=0.05 for the decoy state, ensuring the highest key generation rate and a secure distance of up to 50 km. These protocols were validated experimentally over various transmission distances with standard telecom fiber, using the ID-3000 QKD system in a conventional bi-directional plug-and-play setup. Simulations predicted secure key rates of 1.2 × 105 bits/s for SARG04 and 8.5 × 104 bits/s for BB84 at 10 km, with secure distances of 45 km and 35 km, respectively. The experimental results confirmed these predictions, showing a 30% higher key rate and 20% longer secure distance compared to non-decoy methods. The SARG04 protocol surpassed BB84 in key rate and secure distance, highlighting the twophoton component's role in key generation. This study concludes that the decoy-state method significantly enhances key generation rates and secure distances, optimizing QKD protocols for secure quantum communication. [ABSTRACT FROM AUTHOR]

Free space optical communication with infrared light is a promising secure wireless optical communication technology, where infrared photodetectors are the core component. To date, such applications are based on epitaxial growth narrow‐band semiconductors facing the challenge of large‐area fabrication. Infrared colloidal quantum dots (CQDs) are of interest because of the high‐throughput solution processing. Here, large‐area CQD photodetectors with adjustable wavelengths covering 1.3–2.0 µm. For 1 × 1 mm2 CQD photodetector, the response time achieved within 1 µs at room temperature, responded sharply to the 25 kbps PRBS‐7 communication code is demonstrated. For 1.5 × 1.5 cm2 large‐area CQD photodetectors, a communication rate of 2 kbps is achieved. This work is a step toward the CQD application in the field of optical communications. [ABSTRACT FROM AUTHOR]

This research explores the intriguing realm of eighth-order embedded solitons in highly dispersive media with cubic–quartic nonlinear susceptibilities χ(2) and χ(3), all within the dynamic context of multiplicative white noise and the framework of Itô calculus. Two different approaches are used in this study. The new auxiliary equation approach produces the bright soliton and singular soliton solutions, while the addendum Kudryashov’s approach produces the bright soliton, singular soliton and combo bright–singular soliton solutions. The system under investigation and the results documented within this work stand as pioneering and original contributions to the field of nonlinear optics. Furthermore, a collection of 2D, 3D and contour plots is produced to visually represent the spatial distribution and progression of different solutions. This not only contributes to the advancement of nonlinear equations in theory but also offers valuable insights for practical applications. [ABSTRACT FROM AUTHOR]

We present a novel photon-acid diffusion method to integrate polymer microlenses (MLs) on a four-channel, high-speed photo-receiver consisting of normal-incidence germanium (Ge) p-i-n photodiodes (PDs) fabricated on a 200 mm Si substrate. For a 29 µm diameter PD capped with a 54 µm diameter ML, its dark current, responsivity, 3 dB bandwidth (BW), and effective aperture size at −3 V bias and 850 nm wavelength are measured to be 138 nA, 0.6 A/W, 21.4 GHz, and 54 µm, respectively. The enlarged aperture size significantly decouples the tradeoff between aperture size and BW and enhances the optical fiber misalignment tolerance from ±5 µm to ±15 µm to ease the module packaging precision. The sensitivity of the photo-receiver is measured to be −9.2 dBm at 25.78 Gb/s with a bit error rate of 10−12 using non-return-to-zero (NRZ) transmission. Reliability tests are performed, and the results show that the fabricated Ge PDs integrated with polymer MLs pass the GR-468 reliability assurance standard. The demonstrated photo-receiver, a first of its kind to the best of our knowledge, features decent performance, high yield, high throughput, low cost, and compatibility with complementary metal-oxide-semiconductor (CMOS) fabrication processes, and may be further applied to 400 Gb/s pulse-amplitude modulation four-level (PAM4) communication. [ABSTRACT FROM AUTHOR]

We propose a Dense Wavelength Division Multiplexing (DWDM) Demultiplexer for L band (1565–1635 nm) applications. The design comprises a Y-shaped branch, a circular ring cavity (CRC), a bus waveguide, and a drop waveguide. To simplify the fabrication process, a CRC cavity is used instead of a regular large ring resonator in the design. The diameter of the CRC cavity is 820 nm. Coupled mode theory is used to examine the behaviour of the proposed demultiplexer. Proposed design achieves a narrow resonant wavelength of 12.5 GHz with a 0.1 nm spectral linewidth, a high-quality factor of 15,789, and minimal cross-talk of − 85 dB between adjacent channels. The results confirm that there is a transmission peak at one of the output port, with simultaneous drop of transmission power i.e. zero, at other output port. Additionally, the results convey that the reflection is zero at the peak resonant wavelength for all channels. Further, the proposed design offers a fabrication tolerance of ± 1 nm for air hole and CRC radii at which the resonant wavelength and transmission would not be effected. [ABSTRACT FROM AUTHOR]

In future optical communication applications, broadband tools and technologies are essential for increasing transfer and processing speeds. Conventional microwave tools are too slow and inflexible to meet these demands. Photonic microwave technology offers that most current solution to this issue, utilizing modulation tools to convert microwave signals to the optical domain. However, these modulation tools face significant challenges, including low bandwidth and high voltage requirements. Although various methods have been proposed in recent decades to address these issues, most increase structural complexity and cost without significantly improving modulator performance and bandwidth. In this article, by using a modulation instability in optical fibers, without manipulating and complicating the structure of the modulator and only by using common modulators, their bandwidth was multiplied and the required voltage was significantly reduced. Finally, a special fiber channel was designed, which showed a much better performance.Article Highlights: An optical modulator has been used for broadband applications to increase the transfer and processing speed. By the method of a modulation instability, the bandwidth has reduced by at least 4 times as well as the required voltage. Specially designed fiber has shown lower noise levels and higher channel capacity. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Solar cells are increasingly being utilised for both energy harvesting and reception in free‐space optical (FSO) communication networks. The authors focus on the implementation of a mid‐band p‐In0.01Ga0.99 N/p‐In0.5Ga0.5 N/n‐In0.5Ga0.5 N (PPN) solar cell, boasting an impressive 26.36% conversion efficiency (under 1.5AM conditions) as a receiver within an indoor FSO communication network. Employing a solar cell with dimensions of 1 mm in length and width, the FSO system underwent simulation using Optisystm software, while the solar cell's behaviour was simulated using SCAPS‐1D. The received power from the solar cell was then compared to that of four commercially available avalanche photodiode (APD) receivers. Exploring incident wavelengths spanning 400–700 nm within the visible spectrum, across transmission distances of 5, 10, 15, and 20 m, the study presented current‐voltage (IV) and power‐voltage curves. Notably, the InGaN solar cell exhibited superior electrical power output compared to all commercial APDs. In conclusion, the findings underscore that augmenting received power has the potential to enhance FSO network quality and support extended transmission distances. [ABSTRACT FROM AUTHOR]

The traditional telecommunications band performs poorly in harsh weather conditions due to atmospheric absorption. In recent years, researchers have begun to study optical communication through atmospheric windows, and optical switches are an essential component of optical communication. A broadband atmospheric window optical switch was proposed based on Vanadium dioxide and magnetic polaritons (MP). It is formed by the stacking of two metal-dielectric-metal structures. The simulation results show that the modulation depth can reach 98.38%, and the extinction ratio is 17.93 dB. By calculating the magnetic field, we confirmed that the reason for the "off" mode is the coupling between the different MP modes, while the "on" mode is the excitation of MP. The optical switch we proposed may be applied to radiation cooling and optical satellite communication. [ABSTRACT FROM AUTHOR]

The paper presents a wide-bandwidth, low-polarization semiconductor optical amplifier (SOA) based on strained quantum wells. By enhancing the material gain of quantum wells for TM modes, we have extended the gain bandwidth of the SOA while reducing its polarization sensitivity. Through a combination of tilted waveguide design and cavity surface optical thin film design, we have effectively reduced the cavity surface reflectance of the SOA, thus decreasing device transmission losses and noise figure. At a wavelength of 1550 nm and a drive current of 1.4 A, the output power can reach 188 mW, with a small signal gain of 36.4 dB and a 3 dB gain bandwidth of 128 nm. The linewidth broadening is only 1.032 times. The polarization-dependent gain of the SOA is below 1.4 dB, and the noise figure is below 5.5 dB. The device employs only I-line lithography technology, offering simple fabrication processes and low costs yet delivering outstanding and stable performance. The designed SOA achieves wide gain bandwidth, high gain, low polarization sensitivity, low linewidth broadening, and low noise, promising significant applications in the wide-bandwidth optical communication field across the S + C + L bands. [ABSTRACT FROM AUTHOR]

Summary: Optical millimeter‐wave generation is a predominant approach for the generation of high‐quality carrier signals for future wireless transmissions. This paper proposes an optical frequency 12‐tupling millimeter‐wave generation scheme using three cascaded‐MZMs assisted by polarization multiplexing for carrier suppression. A three‐stage MZM architecture produces the desired sixth‐order sidebands along with the undesired carrier signal. The proper adjustment of polarization direction and angle of polarization rotation lead to the effective suppression of the undesired optical carrier signal. A comprehensive mathematical analysis has been accomplished to evaluate the system's performance, and the obtained results are also validated through simulation findings. The derived results demonstrate that the proposed system is capable of operating over a broad modulation index range extending from 1.5 to 4.5, thereby relaxing the stringent requirements for a constant modulation index. The proposed system generates high‐purity mm‐wave signals with an OSSR of 62.06 dB and an RFSSR of 54.79 dB at a modulation index of 2.6. Moreover, it is also validated that even if the system parameters like modulation index, polarizer rotation angle, and phase difference among RF driving signals deviate from their ideal values to a certain degree, the system performance remains acceptable. The involvement of polarization technique, omission of wavelength‐dependent devices, and a large modulation index operating range make this methodology readily appealing for implementation in radio‐over‐fiber transmissions. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) photonic materials find extensive applications across important fields such as telecommunications, laser radar, and atmospheric remote sensing. In particular, photonic materials activated by main group elements, which exhibit unique spectral features including ultra‐broadband tunable luminescence and long lifetime, have become rising stars in NIR emitting dopants. In this review, the energy level characteristics of the p‐electrons to gain insight into the fundamentals of the NIR optical response from the main group elements are first introduced. Next, the NIR luminescence properties of the main group elements are discussed. Then, the strategy for the design of main group elements activated materials with the desired properties based on local chemical environment engineering is proposed. In addition, recent advances in the applications of main group element (excluding bismuth) activated materials are highlighted. Furthermore, the key scientific issues that urgently need to be solved for such materials, such as the detailed luminescence mechanism are highlighted. Anticipation also extends to the future research trends in this exciting field, including the ways for enhancing luminescence efficiency and extending spectral region, and the efforts for implementing these advancements in novel cutting‐edge technologies like photovoltaics and biomedicine. [ABSTRACT FROM AUTHOR]

This paper simulates the relative performance of various artificial intelligence (AI) techniques when applied to nonlinear distortion compensation in wavelength division multiplexing (WDM) optical communication systems. These procedures are less complex than state-of-the-art compensation methods and do not necessitate prior knowledge about the properties of data in neighboring WDM channels, which can be practically challenging. In this study, Neural Networks (NNs) were integrated into both the transmitter and receiver sections of 3- and 5-channel WDM systems, and the resulting enhancement in performance (Q-factor) was assessed across varying levels of fiber nonlinearities. While the NN stage enhances the system performance, the improvement decreases as expected with the channel number and γ . Next, two-stage architectures that employ a transmitter side NN together with a classifier at the receiver side were modeled. For the systems examined in this paper simple decision tree structures, boosting, forests, extra trees, and multi-layer perceptron (MLP) classifiers all yielded enhanced system performance compared to simple chromatic dispersion compensation (CDC) with the only exception being Ada boosting which decreased the Q-factor for γ = 14 W - 1 k m - 1 . The outcomes of these investigations show that the most effective performance in highly nonlinear WDM systems is attained by employing two-stage systems, with the incorporation of random forest or extra tree AI methods at the receiver side yielding the highest results. [ABSTRACT FROM AUTHOR]

Impulsive noise poses a significant challenge to single input multiple output wireless communication systems. This paper assesses the effectiveness of hybrid combining techniques, namely selection combining‐equal gain combining and selection combining‐maximal ratio combining, in mitigating impulsive noise impact caused by both man‐made and natural phenomena. The evaluation considers three different noise models: Additive white Gaussian noise, Middleton class‐A impulsive noise, and symmetric alpha stable impulsive noise, across Rayleigh and Rician fading channels. Bit error rate is employed to gauge channel performance. Our research contribution lies in the comprehensive assessment of hybrid combining techniques under diverse noise models, addressing a critical research gap in wireless communication. Findings indicate that impulsive noise has a more pronounced impact on channel performance than additive white Gaussian noise, and hybrid combining techniques prove more effective in mitigating these effects. The results hold significant implications for single input multiple output wireless communication systems, guiding the development of more robust and reliable communication systems in impulsive noise scenarios. [ABSTRACT FROM AUTHOR]

The mode rotator is an important component in a PLC-based mode-division multiplexing (MDM) system, which is used to implement high-order modes with vertical intensity peaks, such as LP11b mode conversions from LP11a in PLC chips. In this paper, an LP11 mode rotator based on a polymer/silica hybrid inverted ridge waveguide is demonstrated. The proposed mode rotator is composed of an asymmetrical waveguide with a trench. According to the simulation results, the broadband conversion efficiency between the LP11a and LP11b modes is greater than 98.5%, covering the C-band after optimization. The highest mode conversion efficiency (MCE) is 99.2% at 1550 nm. The large fabrication tolerance of the proposed rotator enables its wide application in on-chip MDM systems. [ABSTRACT FROM AUTHOR]

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Abstract The demand for miniaturized and integrated multifunctional devices drives the progression of high‐performance infrared photodetectors for diverse applications, including remote sensing, air defense, and communications, among others. Nonetheless, infrared photodetectors that rely solely on single low‐dimensional materials often face challenges due to the limited absorption cross‐section and suboptimal carrier mobility, which can impair sensitivity and prolong response times. Here, through experimental validation is demonstrated, precise control over energy band alignment in a type‐II van der Waals heterojunction, comprising vertically stacked 2D Ta2NiSe5 and the topological insulator Bi2Se3, where the configuration enables polarization‐sensitive, wide‐spectral‐range photodetection. Experimental evaluations at room temperature reveal that the device exhibits a self‐powered responsivity of 0.48 A·W−1, a specific directivity of 3.8 × 1011 cm·Hz1/2·W−1, a response time of 151 µs, and a polarization ratio of 2.83. The stable and rapid photoresponse of the device underpins the utility in infrared‐coded communication and dual‐channel imaging, showing the substantial potential of the detector. These findings articulate a systematic approach to developing miniaturized, multifunctional room‐temperature infrared detectors with superior performance metrics and enhanced capabilities for multi‐information acquisition.

Abstract The enhanced capacity of optical networks is a significant advantage within the global telecommunications industry. Optical networks provides transmission of information over large distances with reduced latency. However, the growing intricacy of network topologies poses a significant challenge to network adaptability, network resilience, device compatibility, and service quality in the contemporary era of technology and 5G networks. In light of these challenges, recent studies leverages on disaggregation in the context of Software Defined Network (SDN) and network service orchestrators as a viable remedy. Disaggregated optical systems offer SDON (Software‐Defined Optical Networking) enhanced control options and third‐party dynamism streamlining upgrades and diminishing single vendor dependency. Although, the advancement of disaggregation improves network flexibility and vendor neutrality of Software Defined Optical Networking (SDON), this improvement comes at the cost of reduced scalability and network controllability performance. The current research paper posits two potential resolutions to the aforementioned challenge. The authors present recommendations and an enhanced architecture that leverages Open Network Operating System (ONOS) containers and Kubernetes orchestration to improve scalability inside the Software‐Defined Optical Networking (SDON) architecture. The suggested architectural design has underlining novel flow charts and algorithms that enhances scalability performance by 33% while also preserving flexibility and controllability in comparison to pre‐existing SDON architectures. This architecture also makes use of the Mininet‐Optical physical‐layer architecture to simulate a real‐time scenario, as well as yang models from the Open Disaggregated Transport Network (ODTN) working group, the pioneers of SDONs. A detailed analysis of the rules and procedural processes involved in the implementation of the proposed architecture. In order to demonstrate the practical application of this architectural framework to a real‐world Software‐Defined Optical Network (SDON) system, the pre‐existing SDON ONOS architecture within the Optical Transport Domain Networking (OTDN) working group was adjusted and refined. This adaptation aimed to illustrate the use of ONOS in conjunction with established optical network systems, highlighting the advantages it offers.

ABSTRACTThe lithium niobate on insulator devices confine the light field to submicron size in monocrystalline lithium niobate, to achieve ultra-strong electro-optical interaction and nonlinear optical interaction, and thus extend the frontiers of the photonic research in the past decade. Such devices are manufactured using nano-fabrication technology over the thin-film lithium niobate wafer, which usually stands on a silica insulator layer above the substrate material, including low-loss waveguides, electro-optical modulators, domain engineered structures, high-Q microring resonators and electrical filters etc., and lead to breakthroughs in optical communication, microwave photonics and quantum integration.

In long-range laser communication, adaptive optics tracking systems are often used to achieve high-precision tracking. When recognizing beacon spots for tracking, the traditional threshold segmentation method is highly susceptible to segmentation errors in the face of interference. In this study, an improved DeepLabV3+ network is designed for fast and accurate capture of beacon spots in complex situations. In order to speed up the inference process, the backbone of the model was rewritten as MobileNetV2. This study improves the ASPP (Atrous Spatial Pyramid Pooling) module by splicing and fusing the outputs and inputs of its different layers. Meanwhile, the original convolution in the module is rewritten as a depthwise separable convolution with a dilation rate to reduce the computational burden. CBAM (Convolutional Block Attention Module) is applied, and the focus loss function is introduced during training. The network yields an accuracy of 98.76% mean intersection over union on self-constructed beacon spot dataset, and the segmentation consumes only 12 milliseconds, which realizes the fast and high-precision capturing of beacon spots. [ABSTRACT FROM AUTHOR]

The enhanced capacity of optical networks is a significant advantage within the global telecommunications industry. Optical networks provides transmission of information over large distances with reduced latency. However, the growing intricacy of network topologies poses a significant challenge to network adaptability, network resilience, device compatibility, and service quality in the contemporary era of technology and 5G networks. In light of these challenges, recent studies leverages on disaggregation in the context of Software Defined Network (SDN) and network service orchestrators as a viable remedy. Disaggregated optical systems offer SDON (Software‐Defined Optical Networking) enhanced control options and third‐party dynamism streamlining upgrades and diminishing single vendor dependency. Although, the advancement of disaggregation improves network flexibility and vendor neutrality of Software Defined Optical Networking (SDON), this improvement comes at the cost of reduced scalability and network controllability performance. The current research paper posits two potential resolutions to the aforementioned challenge. The authors present recommendations and an enhanced architecture that leverages Open Network Operating System (ONOS) containers and Kubernetes orchestration to improve scalability inside the Software‐Defined Optical Networking (SDON) architecture. The suggested architectural design has underlining novel flow charts and algorithms that enhances scalability performance by 33% while also preserving flexibility and controllability in comparison to pre‐existing SDON architectures. This architecture also makes use of the Mininet‐Optical physical‐layer architecture to simulate a real‐time scenario, as well as yang models from the Open Disaggregated Transport Network (ODTN) working group, the pioneers of SDONs. A detailed analysis of the rules and procedural processes involved in the implementation of the proposed architecture. In order to demonstrate the practical application of this architectural framework to a real‐world Software‐Defined Optical Network (SDON) system, the pre‐existing SDON ONOS architecture within the Optical Transport Domain Networking (OTDN) working group was adjusted and refined. This adaptation aimed to illustrate the use of ONOS in conjunction with established optical network systems, highlighting the advantages it offers. [ABSTRACT FROM AUTHOR]

Recognized in the 1990s, vortex beams' ability to carry orbital angular momentum (OAM) has significantly contributed to applications in optical manipulation and high-dimensional classical and quantum information communication. However, inherent diffraction in free space results in the inevitable expansion of beam size and divergence contingent upon the OAM, limiting vortex beams' applicability in areas such as spatial mode multiplexing communication, fiber-optic data transmission, and particle manipulation. These domains necessitate vortex beams with OAM-independent propagation characteristics. We introduce iso-propagation vortices (IPVs), vortex beams characterized by OAM-independent propagation behavior, achieved through precise radial index configuration of Laguerre-Gaussian beams. IPVs display notable transmission dynamics, including a reduced quality factor, resilience post-damage, and decreased and uniform modal scattering under atmospheric turbulence. Their distinctive attributes render IPVs valuable for potential applications in imaging, microscopy, optical communication, metrology, quantum information processing, and light-matter interactions. Notably, within optical communication, the case study suggests that the IPV basis, due to its OAM-independent propagation behavior, provides access to a more extensive spectrum of data channels compared with conventional spatial multiplexing techniques, consequently augmenting information capacity. [ABSTRACT FROM AUTHOR]