Wavelength Division Multiplexing Research Articles

Dynamic control, routing, and resource assignment in multi-granular optical node topologies combining wavelength, waveband, and spatial switching for 6G transport networks [Invited

Effective management of end-to-end 6G network services is crucial, with peak capacity requirements for 6G transport connections expected to exceed 1 Tb/s. As demand for high bandwidth rises, there is a growing necessity for high-capacity optical fiber links, including ultra-wideband (UWB) and multiple fiber links within the network. Scaling up to accommodate these demands, designing wavelength-selective switches (WSSs) for such networks significantly increases the port count. To tackle this issue, we propose various multi-granular optical node (MG-ON) architectures utilizing heterogeneous wavelength, waveband, and spatial switching. We evaluate these architectures’ performance against high-capacity wavelength division multiplexed (WDM) networks through various simulation parameters.

Dynamically controllable two-color electromagnetically induced grating via spatially modulated inelastic two-wave mixing

A scheme for controlling two-color electromagnetically induced grating (TCEIG) in a coherently prepared cold atomic ensemble with a four-level inverted Y-type configuration is proposed via exploiting inelastic two-wave mixing process. By adding an intensity mask behind the auxiliary control field, the transmission functions of the incident probe field and the generated signal field are modulated periodically, thereby leading to the formation of TCEIG. Using experimentally achievable parameters, both the probe and signal fields with different frequencies can be simultaneously diffracted into high-order diffractions. It is found that the diffraction efficiencies of TCEIG, especially the first-order diffraction efficiency, can be significantly improved via adjusting the detunings of the probe and signal fields. Furthermore, it is also demonstrated that the diffraction of TCEIG can be manipulated via tuning the intensity and detuning of the control field. Finally, we investigate the influence the phase mismatch on the diffraction of TCEIG. It is shown that the diffraction pattern of the probe field is rather robust against the phase mismatch, while the diffraction intensities of the signal field are suppressed by the phase mismatch. Our scheme may provide a possibility for the all-optical control of optical switch and wavelength division multiplexing.

Suppression of parasitic lasing in erbium doped thin film lithium niobate waveguide amplifier by integrated wavelength division multiplexer

Photonic integrated circuits based erbium doped amplifiers have attracted great interest due to their compact footprint, high gain in the telecom C-band, and high scalability for functional integration. In this work, a wavelength division multiplexer integrated erbium doped waveguide amplifier fabricated on the thin film lithium niobate on insulator platform is demonstrated. An on-chip saturated power of 10 dBm with the net gain around 10 dB is achieved from the monolithically integrated amplifier chip with the footprint of only 3 × 5 mm2. In particular, the suppression of parasitic lasing in the waveguide amplifier is realized thanks to the spectral response of the integrated wavelength division multiplexer. Theoretical analysis of parasitic lasing on amplifier performance is also conducted. The demonstrated integrated erbium doped waveguide amplifier will find great use in various applications based on the thin film lithium niobate on an insulator platform.

The use of a supercontinuum light source for the characterization of passive fiber optic components

Abstract In this article, we report the application of a commercial supercontinuum light source for testing fiber optics components in a broad optical range. We demonstrate that this kind of light can be successfully used to measure the parameters of a number of passive fiber components, such as fiber Bragg gratings, fiber couplers, wavelength division multiplexers, and fibered isolators. We also show that near the double wavelength of the pulsed laser used to pump the nonlinear fiber generating the supercontinuum, the standard optical spectrum analyzers demonstrate the false spectral peak that affects the test results and that using a simple low-cost monochromator placed at the supercontinuum source output permits the elimination of this peak. The results of experiments related to the characterization of passive fiber devices in the broad optical range, from 1 μm to more than 2 μm, are discussed in detail as possible applications of the proposed technique.

A High-Speed Silicon-Photonics WDM Switch for Optical Networks Applications

This article introduces the design of a novel high-speed silicon-photonics hitless switch that adheres to wavelength-division multiplexing (WDM) standards for channel 3 dB bandwidth, channel free spectral range, crosstalk, shape factor, and dispersion. The design combines the advantages of two structures, a compound ring resonator structure, and a Mach–Zehnder interferometer (MZI) modulator. The mathematical treatment for the proposed device is detailed, and two designs are presented. For a switch of five ring resonators, the through (drop) channel 3 dB bandwidth is 60 GHz (38 GHz), channel crosstalk is −24 dB (−24 dB), dispersion is 22 ps/nm (21 ps/nm), shape factor is 0.66 (0.5), and insertion loss is 0.3 dB (1.7 dB). For a switch of nine ring resonators, the through (drop) channel 3 dB bandwidth is 59 GHz (38 GHz), channel crosstalk is −37 dB (−24 dB), dispersion is 28.5 ps/nm (29 ps/nm), shape factor is 0.8 (0.73), and insertion loss is 0.3 dB (2.3 dB). For the five-ring design, the switch-on/off ratio is 30 dB, and for the nine-ring design, it is 31 dB. For both designs, the switching speed is 100 GHz.

Demonstration of 640 Gbps/160 Gbps WDM-PON system based on colorless ONUs

Abstract The Wavelength Division Multiplexing Passive Optical Network (WDM-PON) is considered a highly promising option for next-generation optical access networks. In this work, we propose and demonstrate a WDM-PON network architecture using colorless Optical Network Units (ONUs). Our design employs a single broadband source (comb source) to generate the optical carriers required for bidirectional transmission. We demonstrate the feasibility of implementing a WDM-PON over a 30 km standard single-mode fiber (SSMF-28), with downstream transmission at 640 Gbps and upstream at 160 Gbps. The proposed method involves comparing two WDM-PON networks with 16 channels, which have similar characteristics. In the first system, we use 32 carriers – 16 for downstream and 16 for upstream – while in the second system, only 16 carriers are used for both directions. In addition, this configuration allows us to easily double the total bandwidth of the network by increasing the number of ONUs to 32 and incorporating the unused carriers (the 16 other unused carriers from the second configuration).

Multifunctional hybrid plasmonic gates using the effect of voltage on the surface plasmons frequency change

Development of plasmonic technology has accelerated in recent years, especially considering the benefits of reducing the scattering limit on bends and low losses as well as the small elemental size. In this paper, the effect of voltage application on changing the frequency of surface plasmons is investigated. Our hybrid device controls light sources using electric voltage. By applying an external voltage to the metal plates and creating a magnetic field, the density of the electrons on the metal surface changes; thus, surface plasmons resonance frequency shifts. To this end, a multifunctional plasmonic gate with a dimension of 95 nm × 95 nm was designed and simulated to evaluate this effect. This structure is suitable for use as AND, NOR, NOT, XOR, and NAND gates. The contrast ratio between the change of state from logic “0” to logic “1” is approximately 29 dB, and the transfer ratio (transmittance ratio) of output in logic “1” is over 85%. The proposed device has low dimensions, a high contrast ratio, and a high transmittance ratio. This device uses four gates: AND, NOR, NOT, XOR, and NAND, which can be achieved in plasmonic integrated circuits with the wavelength division multiplexing (WDM) technique.

Integrated lithium niobate Vernier micro-ring filter with wide and fast tuning capabilities

Tunable optical micro-ring filters play significant roles in optical communications, microwave photonics, and photonic neural networks. Typical micro-ring filters are based on either a thermo-optic (TO) effect with microsecond timescales or an electro-optic (EO) effect with a limited tuning range. Here, we report a continuously tunable lithium niobate on insulator (LNOI) Vernier cascaded micro-ring filter with wire-bonded packaging integrated with both TO and EO tuning electrodes, featuring a 40-nm free spectral range (FSR), 2.3 GHz EO bandwidth, and a high sidelobe suppression ratio of 21.7 dB, simultaneously. Our high-performance optical micro-ring filter could become an important element in future LNOI photonic circuits with applications in high-capacity wavelength-division multiplexing (WDM) systems, broadband microwave photonics, fast-tunable external-cavity lasers, and high-speed photonic neural networks.

Demonstration of a Three Node Wavelength Division Multiplexed Hybrid Quantum-Classical Network through Multicore Fiber

Demonstration of a Three Node Wavelength Division Multiplexed Hybrid Quantum-Classical Network through Multicore Fiber

Advanced Modulation Formats for 400 Gbps Optical Networks and AI-Based Format Recognition.

The integration of communication and sensing (ICAS) in optical networks is an inevitable trend in building intelligent, multi-scenario, application-converged communication systems. However, due to the impact of nonlinear effects, co-fiber transmission of sensing signals and communication signals can cause interference to the communication signals, leading to an increased bit error rate (BER). This paper proposes a noncoherent solution based on the alternate polarization chirped return-to-zero frequency shift keying (Apol-CRZ-FSK) modulation format to realize a 4 × 100 Gbps dense wavelength division multiplexing (DWDM) optical network. Simulation results show that compared to traditional modulation formats, such as chirped return-to-zero frequency shift keying (CRZ-FSK) and differential quadrature phase shift keying (DQPSK), this solution demonstrates superior resistance to nonlinear effects, enabling longer transmission distances and better transmission performance. Moreover, to meet the transmission requirements and signal sensing and recognition needs in future optical networks, this study employs the Inception-ResNet-v2 convolutional neural network model to identify three modulation formats. Compared with six deep learning methods including AlexNet, ResNet50, GoogleNet, SqueezeNet, Inception-v4, and Xception, it achieves the highest performance. This research provides a low-cost, low-complexity, and high-performance solution for signal transmission and signal recognition in high-speed optical networks designed for integrated communication and sensing.

Optical light scattering to improve image classification via wavelength division multiplexing

Machine learning is constantly contributing significant progress in many areas while posing huge demands for computing resources. It has been demonstrated the feasibility of leveraging random light scattering to decrease the computational resource demands of image classification algorithms. However, optical devices in optical random scattering systems, such as cameras, constrain the bandwidth of the entire system. In this study, a high-speed scattering system based on wavelength division multiplexing (WDM) was proposed. By employing the high bandwidth semiconductor lasers and quadrant PIN detectors, this WDM scattering system achieves over a 1000-times increase in acquisition speed compared to the traditional camera-based spatial scattering system. Moreover, this WDM scattering system has been demonstrated to improve the classification accuracy for RC on nine datasets, including MNIST, Chest_X-ray, and Malaria, by 26.15%.

From Optical Fiber Communications to Bioimaging: Wavelength Division Multiplexing Technology for Simplified in vivo Large-depth NIR-IIb Fluorescence Confocal Microscopy.

Near-infrared II (NIR-II, 900-1880nm) fluorescence confocal microscopy offers high spatial resolution and extensive in vivo imaging capabilities. However, conventional confocal microscopy requires precise pinhole positioning, posing challenges due to the small size of the pinhole and invisible NIR-II fluorescence. To simplify this, a fiber optical wavelength division multiplexer (WDM) replaces dichroic mirrors and traditional pinholes for excitation and fluorescence beams, allowing NIR-IIb (1500-1700 nm) fluorescence and excitation light to be coupled into the same optical fiber. This streamlined system seamlessly integrates key components-excitation light, detector, and scanning microscopy-via optical fibers. Compared to traditional NIR-II confocal systems, the fiber optical WDM configuration offers simplicity and ease of adjustment. Notably, this simplified system successfully achieves optical sectioning imaging of mouse cerebral blood vessels up to 1000µm in depth. It can discern tiny blood vessels (diameter: 4.57µm) at 800µm depth with a signal-to-background ratio (SBR) of 5.34. Additionally, it clearly visualizes liver vessels, which are typically challenging to image, down to a depth of 300µm.

Enhanced Carrier Phase Recovery Using Dual Pilot Tones in Faster-than-Nyquist Optical Transmission Systems

Compared with high spectrum efficiency faster-than-Nyquist (FTN) backbone network, an enhanced carrier phase recovery based on dual pilot tones is more sensitive to capital cost in FTN metropolitan areas as well as inter-datacenter optical networks. The use of distributed feedback (DFB) lasers is a way to effectively reduce the cost. However, under high symbol rate FTN systems, equalization-enhanced phase noise (EEPN) induced by a DFB laser with large linewidth will significantly deteriorate the system performance. What is worse, in FTN systems, tight filtering introduces inter-symbol interference so severe that the carrier phase estimation (CPE) algorithm of the FTN systems is more sensitive to EEPN, thus it will lead to a more serious cycle slip problem. In this paper, an enhanced carrier phase recovery based on dual pilot tones is proposed to mitigate EEPN and suppress cycle slip, in which the chromatic dispersion (CD)-aware Tx and LO laser phase noise is estimated, respectively. Offline experiments results under 40 Gbaud polarization multiplexing (PM) 16-quadrature amplitude modulation (QAM) FTN wavelength division multiplexing (FTN-WDM) systems at 0.9 acceleration factor, 5 MHz laser linewidth, and 500 km transmission demonstrate that the proposed algorithm could bring about 0.65 dB improvement of the required SNR for the normalized generalized mutual information of 0.9 compared with the training sequence-based cycle slip suppression carrier phase estimation (TS-CSS) algorithm.

Switchable multi-wavelength pulse fiber laser with mode conversion

A switchable multi-wavelength pulse fiber laser based on dual-Sagnac comb filter, nonlinear optical loop mirror (NOLM) and a homemade mode selective coupler (MSC) is proposed and experimentally demonstrated. The dual-Sagnac comb filter and the NOLM are adopted as wavelength selective filter and saturable absorber (SA) in this work, respectively. This proposed fiber laser has a maximum output wavelength number of four. And the fiber laser can output multi-wavelength pulse lasers within a certain interval of the integer times of 1 nm and 1.9 nm. Moreover, when the pump power is 150 mW, the mode-locked fiber laser with the pulse repetition frequency of 120 MHz, a pulse duration of 4 ns and pulse interval of 8.3 ns have been realized via carefully adjusting the PC. And the fiber laser has a maximum output power of 226 μW under 300 mW pump power. In addition, the homemade MSC is utilized as mode converter to realize mode conversion up to LP31 and the mode purity is higher than 92 %. This work can find applications in wavelength division multiplexing (WDM) and the optical communication.

Maximizing transmission capacity in optical communication systems utilizing a microresonator comb laser source with adaptive modulation and bandwidth allocation strategies

Traditional optical communication systems employ bulky laser arrays that lack coherence and are prone to severe frequency drift. Dissipative Kerr soliton microcombs offer numerous evenly spaced optical carriers with a high optical signal-to-noise ratio (OSNR) and coherence in chip-scale packages, potentially addressing the limitations of traditional wavelength division multiplexing (WDM) sources. However, soliton microcombs exhibit inhomogeneous OSNR and linewidth distributions across the spectra, leading to variable communication performance under uniform modulation schemes. Here, we demonstrate, for the first time, to our knowledge, the application of adaptive modulation and bandwidth allocation strategies in optical frequency comb (OFC) communication systems to optimize modulation schemes based on OSNR, linewidth, and channel bandwidth, thereby maximizing capacity. Experimental verification demonstrates that the method enhances spectral efficiency from 1.6 to 2.31 bit ⋅ s−1 ⋅ Hz−1, signifying a 44.58% augmentation. Using a single-soliton microcomb as the light source, we achieve a maximum communication capacity of 10.68 Tbps after 40 km of transmission in the C-band, with the maximum single-channel capacity reaching 432 Gbps. The projected combined transmission capacity for the C- and L-bands could surpass 20 Tbps. The proposed strategies demonstrate promising potential of utilizing soliton microcombs as future light sources in next-generation optical communication.

All‐Optical Imaging Using Perovskite Nanocrystals Based on Spectro‐Spatial Correlation

AbstractThe exponential growth of data from sensors and internet‐connected devices has challenged traditional electronic computing, particularly in processing speed and power efficiency. Optical information processing, with its inherent high speed and parallelism, offers a promising solution. Moreover, optical processing is vital for developing all‐optical networks, where all‐optical imaging is essential. In this paper, a novel all‐optical imaging technique that leverages in situ anion exchange reactions between perovskite nanocrystals to create an array of pixels with tunable emission wavelengths is proposed. This method enables the conversion of UV light, whether transmitted or reflected by an object, into the visible spectrum, thereby establishing a direct correlation between spectral and spatial information. By employing wavelength division multiplexing (WDM), the approach reduces the dimensionality of information acquisition from two dimensions to one, enhancing imaging speed. This innovation paves the way for significant advancements in all‐optical imaging and image processing, offering new possibilities for faster and more efficient imaging technologies.

RGB-Single-Chip OLEDs for High-Speed Visible-Light Communication by Wavelength-Division Multiplexing.

Organic light-emitting diodes (OLEDs) have been developed for high-speed transmitters of visible-light communication (VLC) but so far the possibility of direct fabrication of multiple colors on a single substrate has not been exploited for multi-Gbps data transmission. Very fast red-, green-, and blue (RGB)-emitting OLEDs are developed on a single substrate to realize high data transmission speed by wavelength division multiplexing (WDM). -6dB electrical bandwidth of over 100MHz is achieved for all colors by selecting fluorescent materials with nanosecond emission lifetimes and little overlap between their emission spectra and incorporating them into OLEDs designed for high-speed operation. Optical microcavities in top-emitting OLED structures are used to minimize spectral overlap. A record data transmission rate for an OLED transmitter system of 3.2Gbps is demonstrated, by transmitting data with the 3 colors simultaneously and separating each data by dichroic mirrors. The results show that WDM with integrated RGB pixels is a useful way to increase the data transmission rate of a VLC system based on OLED transmitters, which has the potential to enable multi-gigabit transmission by displays. The availability of high-speed multiple-color devices as developed here also expands applications of OLEDs for spectroscopy, sensing, and ranging.

Multi-task photonic reservoir computing: wavelength division multiplexing for parallel computing with a silicon microring resonator

Nowadays, as the ever-increasing demand for more powerful computing resources continues, alternative advanced computing paradigms are under extensive investigation. Significant effort has been made to deviate from conventional Von Neumann architectures. In-memory computing has emerged in the field of electronics as a possible solution to the infamous bottleneck between memory and computing processors, which reduces the effective throughput of data. In photonics, novel schemes attempt to collocate the computing processor and memory in a single device. Photonics offers the flexibility of multiplexing streams of data not only spatially and in time, but also in frequency or, equivalently, in wavelength, which makes it highly suitable for parallel computing. Here, we numerically show the use of time and wavelength division multiplexing (WDM) to solve four independent tasks at the same time in a single photonic chip, serving as a proof of concept for our proposal. The system is a time-delay reservoir computing (TDRC) based on a microring resonator (MRR). The addressed tasks cover different applications: Time-series prediction, waveform signal classification, wireless channel equalization, and radar signal prediction. The system is also tested for simultaneous computing of up to 10 instances of the same task, exhibiting excellent performance. The footprint of the system is reduced by using time-division multiplexing of the nodes that act as the neurons of the studied neural network scheme. WDM is used for the parallelization of wavelength channels, each addressing a single task. By adjusting the input power and frequency of each optical channel, we can achieve levels of performance for each of the tasks that are comparable to those quoted in state-of-the-art reports focusing on single-task operation. We also quantify the memory capacity and nonlinearity of each parallelized RC and relate these properties to the performance of each task. Finally, we provide insight into the impact of the feedback mechanism on the performance of the system.

High gain distributed Raman amplifier for orbital angular momentum mode-division multiplexing and wavelength-division multiplexing in a 104-km ring-core fiber over the C + L band.

Mode-division multiplexing (MDM) and wavelength-division multiplexing (WDM) are regarded as effective solutions for enhancing the communication capacity of fiber-optic transmission systems. To extend the transmission distance, a suitable amplification technique is required to amplify the signal light, with distributed Raman amplifier (DRA) offering a high-flat gain. In this paper, we experimentally demonstrate the transmission of 3 orbital angular momentum (OAM) mode-division multiplexing and 9 wavelength-division multiplexing ranging from 1530 nm to 1610 nm over a 104-km self-designed ring-core fiber (RCF) with the assistance of DRA. The homemade all-fiber mode selective couplers (MSCs) can (de)multiplex OAM modes (OAM01, OAM11, OAM21) efficiently in long-distance MDM + WDM fiber-optic transmission systems. The OAM-DRA provides high gain (with an on-off gain greater than 10 dB) as well as flat gain (with a differential wavelength gain of less than 0.88 dB and a differential mode gain of less than 0.28 dB) over the C + L band.

Over 10‐W, 2.0‐μm, Broadband, All‐Fiber Amplified Spontaneous Emission Source Based on Spectrum Combination

Herein, Tm‐doped fiber (TDF) amplified spontaneous emission (ASE) and Ho‐doped fiber ASE to realize a high‐power, 2.0‐μm‐broadband, all‐fiber ASE source are combined. By in‐band pumping the Ho‐doped fiber ASE with TDF ASE, an output power of 17.7 W is achieved. Subsequently, a 1500–1970/1980–2200‐nm wavelength division multiplexer is utilized to combine the Tm‐doped and Ho‐doped fiber ASE sources. The combined ASE source exhibits a maximum output power of 10.9 W, a full width at half maximum of 67 nm, a spectral range of 1910–2086 nm, a root–mean–square power fluctuation of 0.17% in 30 min, no self‐pulsing, and no self‐excited oscillation. To the best of knowledge, such a high output power has not been previously reported for Ho‐doped fiber ASE sources and 2.0‐μm‐broadband all‐fiber ASE sources. Thus, spectrum combination can effectively yield a high‐power fiber ASE source with a broad bandwidth.