Multiplexed Data Transmission Research Articles

Multidimensional Fiber‐to‐Chip Optical Processing Using Photonic Integrated Circuits

AbstractMultidimensional multiplexing technologies have been proven to be a promising scheme to meet the demands of high‐capacity optical interconnects and optical processing networks. However, challenges remain to realize multidimensional hybrid multiplexing data transmission and signal processing between few‐mode fiber transmission links and on‐chip optical processing networks, since the optical coupling between fiber and chip is almost exclusively in the single‐mode regime. Here, a multidimensional fiber‐to‐chip optical processing system is proposed and demonstrated for hybrid wavelength‐, mode‐, and polarization‐division multiplexing signals, where multidimensional coupling between few‐mode fiber transmission link and on‐chip multi‐mode processing network is realized by using a 3D photonic integrated (de)multiplexers on a glass chip as well as 2D photonic integrated (de)multiplexers on a silicon chip, and the on‐chip multidimensional optical processing network composed by parallel cascaded micro‐ring resonator array performs a function of reconfigurable optical add/drop multiplexer. By operating wavelength‐division multiplexing in conjunction with mode‐division multiplexing and polarization‐division multiplexing, the communication bandwidth of fiber‐to‐chip optical processing systems can be further scaled.

An Ultrasound Matrix Transducer for High-Frame-Rate 3-D Intra-cardiac Echocardiography

Described here is the development of an ultrasound matrix transducer prototype for high-frame-rate 3-D intra-cardiac echocardiography. The matrix array consists of 16×18 lead zirconate titanate elements with a pitch of 160 µm×160 µm built on top of an application-specific integrated circuit that generates transmission signals and digitizes the received signals. To reduce the number of cables in the catheter to a feasible number, we implement subarray beamforming and digitization in receive and use a combination of time-division multiplexing and pulse amplitude modulation data transmission, achieving an 18-fold reduction. The proposed imaging scheme employs seven fan-shaped diverging transmit beams operating at a pulse repetition frequency of 7.7 kHz to obtain a high frame rate. The performance of the prototype is characterized, and its functionality is fully verified. The transducer exhibits a transmit efficiency of 28 Pa/V at 5 cm per element and a bandwidth of 60% in transmission. In receive, a dynamic range of 80 dB is measured with a minimum detectable pressure of 10 Pa per element. The element yield of the prototype is 98%, indicating the efficacy of the manufacturing process. The transducer is capable of imaging at a frame rate of up to 1000 volumes/s and is intended to cover a volume of 70°×70°×10 cm. These advanced imaging capabilities have the potential to support complex interventional procedures and enable full-volumetric flow, tissue, and electromechanical wave tracking in the heart.

Handling mode and polarization in fiber by fs-laser inscribed (de)multiplexer and silicon switch array

The emergence of dynamic optical switching has opened up new perspectives for lightening the ever growing load on the electrical switches and routers, to meet the increasing demand on high-speed and flexible data processing and management in fiber-optic communications. Despite diversity schemes of optical switching in the single-mode regime, multi-mode switching of the hybrid fiber and chip system enabled by photonic integrated circuits, especially for the fiber-chip-fiber system, is still an outstanding challenge. Here, we propose and demonstrate the mode and polarization transmission and switching fiber-chip-fiber system with few-mode fibers (FMFs), including the FMF links for mode- and polarization-division multiplexing data transmission, the femtosecond (fs)-laser inscribed 3-dimensional (3D) photonic lantern silica chip for (de)multiplexing and coupling between FMFs and chip, and the topology-optimized N × N non-blocking 2-dimensional (2D) silicon switch array chip for switching and routing. Using 30-Gbaud quadrature phase-shift keying signals on wavelength-division multiplexing (WDM) channels, the WDM-compatible hybrid mode/polarization transmission, switching and routing system with FMFs, fs-laser inscribed silica (de)multiplexing chip and silicon switch array chip are demonstrated in the experiment with favorable operation performance. The demonstration may open the door for developing robust multi-dimensional optical data processing in fiber-optic communication systems with versatile fibers and chips.

Wideband and Low-Loss Mode Scrambler for Few-Mode Fibers Based on Distributed Multiple Point-Loads

We propose a new type of all-fiber mode scrambler for mode division multiplexed data transmission based on few mode fibers. By randomly placing multiple point-loads along the fiber length, low loss and wideband mode coupling is obtained amongst all the guided modes. The effect of mode coupling is simulated from a single point-load to multiple point-loads with a specific focus on the insertion loss and wavelength dependence. In an exemplar experimental demonstration we present a mode scrambler for step-index two mode fibers incorporating 150 randomly located point-loads. Uniform mode coupling is achieved over the C band with an insertion loss of less than 1 dB.

Applications of Multiplexers and Demultiplexers in Network Communication

The aim of this research paper is to provide a general overview of Mux and Demux. This research paper starts with a brief description of these electronic devices. A multiplexer, also known as a data selector, is a system that can merge two or more data lines into a single data line for transmission to another venue. A demultiplexer, also known as a data distributor, is a device that divides a single, multiplexed data transmission line into individual data signals. This article addresses the 1 to 4 multiplexer and demultiplexer. Various applications of mux and demux in the fields of telephone and satellite communication, as well as uses of computer science, are discussed.

Polarization control and mode optimization of 850\xa0nm multi-mode VCSELs using surface grating

To control the polarization of 850 nm multi-mode oxide-confined vertical-cavity surface-emitting lasers (VCSELs), monolithically integrated surface gratings are investigated. VCSELs with different grating parameters are simulated by the rigorous coupled-wave analysis (RCWA) method. Optical field intensity of two polarization orientations with different grating periods and duty cycles is obtained. The mode characteristics of VCSELs with different grating parameters are achieved by FDTD method. 850 nm surface grating VCSELs are fabricated and characterized, a maximum orthogonal polarization suppression ratio (OPSR) of 20.7 dB is observed. Meanwhile, VCSEL’s output mode characteristics are improved by integrating the surface grating. Application of integrated surface grating technique to achieve dynamically polarization-stable multi-mode VCSELs which enable polarization division multiplexed data transmission, the data throughput over a given link can be doubled.

Downlink data transmission for high‐speed trains in 5G communication systems

In this study, a new transmitter–receiver approach for high-speed train (HST) downlink orthogonal frequency division multiplexing (OFDM) data transmission and detection in fifth generation (5G) communication systems is proposed. The proposed method uses a new Doppler shift frequency (DSF) estimation method, proposed in this study, to calculate the channel tap DSFs at the HST receiver. These estimated DSFs are used to calculate the channel taps’ angle of departure (AoD). Using the projected AoDs, the transmitter beamformer adjusts its coefficients to suppress the non-line-of-sight (NLoS) channel taps and a DSF compensation block is used to mitigate the line-of-sight channel tap DSF. Simulation results indicate the fidelity of the proposed DSF estimation method and the proposed transmitter–receiver approach. Due to the accuracy of the proposed DSF estimation method and the effectiveness of the beamformer in suppressing the NLoS channel taps, the approach of using a classic digital modulation and demodulation method instead of the OFDM scheme is appraised. Simulation results indicate that this shift from the OFDM modulation to the classic modulation results in a data detection approach which has acceptable accuracy, low computational complexity, and high spectral efficiency.

Satellite Communication System adopts OFDM-MIMO Technology with High Speed Connectivity

The space communication development has strong urgent requirement for technology upgrading and evolution. The satellite communication capacity can be advanced by the application of higher data transmission efficiency. It will be contented with diversified High Throughput Satellite (HTS) communication application requirements. A satellite communication system architecture design featured by higher transmission efficiency using Multi-Input & Multi-Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) technology which has been wildly used in next generation of terrestrial wireless communications has been presented. It is proposed to solving problems on multiplexing data transmission, receiving signal’s anti-interference, and supporting various multi-user terminals. The throughput and application analysis was done to evaluate system performance in terms of diverse HTSs. A comprehensive evaluation and simulation analysis of space communication application efficiency are carried out to verify the feasibility of basic space application under the diverse simulation conditions. The total throughput of the communication system can reach up to 259Gbps as extremely high speed connectivity, and the maximum spectrum efficiency is close to the ultimate performance of 100bits/s/Hz.

Adiabatic higher-order mode microfibers based on a logarithmic index profile.

Optical fibers with a logarithmic index profile can provide invariant mode field diameters along a tapered fiber, which enables adiabatic mode transitions for higher-order mode (HOM) microfibers. A microfiber with a waist diameter of ∼2 µm is fabricated with an insertion loss lower than 0.03 dB for the LP01 and 0.11 dB for the LP11 mode. The concept of the low loss HOM microfibers can be further extended to include more than one fiber and a 2×2 few mode microfiber coupler is fabricated/characterized in our experiments. These single or multiple spatial channel HOM microfibers are beneficial for various applications, including in particle propulsion, atom trapping, optical sensing and space division multiplexed data transmission systems.

Photonic crystal structured blue µLED with aperture size dependent data transmission performance in plastic fiber link

A comprehensive comparison on the data transmission performance of photonic crystal structured micro light-emitting diodes (PC-µLEDs) with different aperture sizes is realized for high-speed visible light communication application. The 120×120-µm2 large PC-µLED exhibits the largest optical power of 580 µW and the highest external quantum efficiency of 2.5%; however, it also demonstrates the lowest analog modulation bandwidth of only 72 MHz. By contrast, the smallest PC-µLED with 20×20-µm2 aperture emits the lowest optical power of 37 µW but provides the highest 3-dB bandwidth of 162 MHz. After optimizing the operating parameters for data transmission, the trade-off between output power and encoding bandwidth is observed to improve the transmission performance. The PC-µLED with mesa length of 60–80 µm can transmit on-off keying (OOK) data format at 500 Mbit/s under error-free BER criterion. In particular, the device with a mesa area of 80×80-µm2 successfully carries the 300-MBaud 4-level pulse amplitude modulation (PAM-4) data with corresponding data rate of 600 Mbit/s under KP4 forward error correction (FEC) required BER. Furthermore, the quadrature-amplitude-modulation (QAM) orthogonal frequency division multiplexing (OFDM) data transmission is also performed, and the highest data rate of 2 Gbit/s under FEC criterion is allowable by using the PC-µLED with a mesa aperture of 80×80-µm2.

Nonlinearity-Free Coherent Transmission in Hollow-Core Antiresonant Fiber

We demonstrate the first multiterabit/s wavelength division multiplexing data transmission through hollow-core antiresonant fiber (HC-ARF). In total, 16 channels of 32-GBd dual-polarization Nyquist-shaped 256QAM signal channels were transmitted through a 270-m-long fiber without observing any power penalty. In a single-channel high power transmission experiment, no nonlinearity penalty was observed for up to 1 W of received power, despite the very low chromatic dispersion of the fiber (<2 ps/nm/km). Our simulations show that such a low level of nonlinearity should enable transmission at 6.4 Tb/s over 1200 km of HC-ARF, even when the fiber attenuation is significantly greater than that of SMF-28. As signals propagate through hollow-core fibers at close to the speed of light in vacuum such a link would be of interest in latency-sensitive data transmission applications.

Filtered Multicarrier OFDM Encoding on Blue Laser Diode for 14.8-Gbps Seawater Transmission

A GaN blue laser diode (BLD)-based visible-light communication link is demonstrated in a seawater environment to provide 16-quadrature amplitude modulation orthogonal frequency-division multiplexing (QAM OFDM) data transmission at 14.8 Gbps over 1.7 m. Lengthening the seawater distance to 10.2 m only decreases the transmission data rate by 4 Gbps, as caused by the frquency response limitation of the used avalanche photodiode. To optimize the QAM-OFDM transmission, the sampling rate of the encoded data is compromised to avoid the aliasing and oversampling effects during the waveform extraction procedure. The sampling rate is optimized to 3–5 times of the encoded data bandwidth for suppressing peak-to-average power ratio. Oversampling not only filters out background noise but also attenuates data amplitude to degrade transmission performance. Without using the multicarrier spectrally filtered OFDM, the 16-QAM OFDM data format only promotes the transmission capacity of BLD up to 7.6 Gbps in seawater. With spectrally filtering out the sidelobes of each OFDM subcarrier, the allowable modulation bandwidth is greatly improved from 1.9 to 2.7 GHz, as the intercarrier interference induced crosstalk between subbands is relieved to improve the SNR of the carried data with a raw data rate of up to 10.8 Gbps.

Elliptical Core Few Mode Fibers for Multiple-Input Multiple Output-Free Space Division Multiplexing Transmission

We experimentally demonstrate space division multiplexed data transmission using the LP01, LP11a and LP11b modes over a 1 km length of elliptical-core few mode fiber at 1550 nm using 10 Gb/s ON–OFF keying data per spatial channel. Space division multiplexed transmission without the use of any multiple input multiple output digital signal processing showed no power penalty relative to the single-mode or the back to back cases.

Full-duplex bidirectional data transmission link using twisted lights multiplexing over 1.1-km orbital angular momentum fiber.

We present a full-duplex bidirectional data transmission link using twisted lights multiplexing over 1.1-km orbital angular momentum (OAM) fiber. OAM+1 and OAM−1 modes carrying 20-Gbit/s quadrature phase-shift keying (QPSK) signals are employed in the downlink and uplink transmission experiments. The observed mode crosstalks are less than −15.2 dB, and the full-duplex crosstalks are less than −12.7 dB. The measured full-duplex optical signal-to-noise ratio (OSNR) penalties at a bit-error rate (BER) of 2 × 10−3 are ~2.4 dB in the downlink transmission and ~2.3 dB in the uplink transmission. The obtained results show favorable full-duplex twisted lights multiplexing data transmission performance in a km-scale OAM fiber link.

5-port optical router based on Si microring optical switches for photonic networks-on-chip

We demonstrate a five-port optical router composed of eight silicon microring optical switches tuned by thermo-optic effect. The optical signal-to-noise ratio of the device on the tested routing states is over 11 dB at the working wavelength. 32-Gb/s data transmission has been performed on its 20 optical links, and eight-channel wavelength division multiplexing data transmission in the wavelength range from 1525 to 1565 nm has been implemented to expand its communication capacity. The average energy efficiency of the optical router is 68.2 fJ/bit, and its response time is $\sim 20~\mu \text{s}$ .

Characterization of Mode Coupling in Few-Mode FBG With Selective Mode Excitation

We present the results on fabrication and the characterization of few-mode fiber Bragg gratings (FM-FBGs) inscribed in two mode and four mode step-index fibers. Under the conditions of selective input mode launching, coupling between specific modes of interest can be selectively excited and the self-coupling and cross-coupling properties at the associated resonant wavelengths can be clearly identified and verified by observing the reflected mode intensity profiles. Such FM-FBGs can potentially be used as reflective mode-converters for mode division multiplexed data transmission systems.

Reconfigurable non-blocking four-port optical router based on microring resonators.

A reconfigurable non-blocking four-port optical router with the least optical switches is demonstrated. The device is based on microring resonators tuned through thermo-optic effect. The optical signal-to-noise ratio of the device at its nine routing states is about 15dB. A 25Gbps data transmission has been performed on its whole 12 optical links, and 8-channel wavelength division multiplexing data transmission has been implemented to expand its communication capacity. The energy efficiency of the device is 23fJ/bit, and the response time of the device is about 25μs.

Dual mode fused optical fiber couplers suitable for mode division multiplexed transmission

We experimentally demonstrate 2 × 2 and 3 × 3 fused fiber couplers made from dual mode fiber. A unique mode dependent power transfer characteristics as a function of pulling length is obtained that support various optical functionalities. Exploiting this we demonstrate several devices of interest for mode division multiplexed data transmission including LP11 mode filter, LP11 mode tap coupler, and 50:50 power splitter for both LP01 and LP11 modes.

무선 센서 망에서 생체 시스템 기반 에너지 효율적인 노드 스케쥴링 기법

센서 네트워크에서 기본적으로 고려되어야 하는 것은 센서 노드의 에너지 소모 문제이다. 이를 해결하기 위해 많은 연구들이 진행되어 왔지만 에너지 소모 문제와 더불어 트레이드오프 관계를 갖는 지연 문제도 간과할 수 없는 부분이다. 본 논문은 생체시스템을 모방하여 무선 센서망에서 에너지의 소모와 지연시간을 줄이기 위한 BISA(Bio-inspired Scheduling Algorithm)를 제안한다. BISA는 에너지 효율성이 높은 라우팅 경로를 탐색하고 다중채널을 이용하여 데이터 전송의 경로를 다중화하여 데이터 전송을 위한 에너지 소모와 지연시간을 최소화한다. 모의실험을 통해 제안한 방식이 효율적으로 에너지를 소모함과 동시에 요구지연시간을 보장함을 확인한다. The energy consumption problem should be taken into consideration in wireless sensor network. Many studies have been proposed to address the energy consumption and delay problem. In this paper, we propose BISA(Bio-inspired Scheduling Algorithm) to reduce the energy consumption and delay in wireless sensor networks based on biological system. BISA investigates energy-efficient routing path and minimizes the energy consumption and delay using multi-channel for data transmission by multiplexing data transmission path. Through simulation, we confirm that the proposed scheme guarantees the efficient energy consumption and delay requirement.

Towards high-capacity fibre-optic communications at the speed of light in vacuum

Wide-bandwidth signal transmission with low latency is emerging as a key requirement in a number of applications, including the development of future exaflop-scale supercomputers, financial algorithmic trading and cloud computing. Optical fibres provide unsurpassed transmission bandwidth, but light propagates 31% slower in a silica glass fibre than in vacuum, thus compromising latency. Air guidance in hollow-core fibres can reduce fibre latency very significantly. However, state-of-the-art technology cannot achieve the combined values of loss, bandwidth and mode-coupling characteristics required for high-capacity data transmission. Here, we report a fundamentally improved hollow-core photonic-bandgap fibre that provides a record combination of low loss (3.5 dB km-1) and wide bandwidth (160 nm), and use it to transmit 373 x 40 Gbit s-1 channels at a 1.54 ms km-1 faster speed than in a conventional fibre. This represents the first experimental demonstration of fibre-based wavelength division multiplexed data transmission at close to (99.7%) the speed of light in vacuum