Phase Modulation Formats Research Articles

Phase-locking-free all-optical matching system for 100 Gbaud QPSK optical signal.

Photonic firewall is a monitoring protection device that will directly detect and locate optical network attacks at the optical layer, which can effectively ensure the security of optical networks. An all-optical matching system is the core part of photonic firewall, which determines the performance of a photonic firewall, so it is of great significance to research and develop all-optical matching system for high-speed and high-order modulation formats signals. At present, an all-optical matching system for binary modulation formats is relatively mature, but the all-optical matching system for high-order phase modulation format signals is still limited by how to solve the problem of phase synchronization. In this paper, a new all-optical matching system based on self-interference matching is proposed for quadrature phase shift keying (QPSK) optical signal, which avoids the introduction of local target sequence optical signals and phase-locking circuits. The theoretical analysis and simulation verification are conducted for the designed system. The results demonstrate that the system can accurately identify and locate 4-symbol or 8-symbol target sequences in the input QPSK optical signals with 16-symbol and 32-symbol data sequences at a data rate of 100 Gbaud.

Reconfigurable all-optical pattern-matching system for phase modulation formats based on phase-sensitive amplification in highly nonlinear fiber

All-optical pattern-matching system is to compare the input data with the target sequence to implement the data filtering directly in the optical layer. However, for current all-optical pattern-matching systems, one pattern-matching system can only match one modulation format, which limits its application. In this paper, a reconfigurable all-optical pattern-matching system for phase modulation formats is proposed. Taking advantage of phase-sensitive amplification (PSA) in highly nonlinear fiber (HNLF), the system can match various phase modulation formats through optical switches configured by a controller. We first evaluate the feasibility of the proposed system for binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK) modulation formats with the transmission rates of 100 Gbaud and 200 Gbaud. The results show that our proposed system can correctly recognize and locate the position of the target sequence. Next, we analyze the extinction ratio (ER), contrast ratio (CR), Q factor, and bit error rate (BER) by changing the optical signal-to-noise ratio (OSNR) values of BPSK and QPSK signals to evaluate the noise performance. The proposed reconfigurable all-optical pattern-matching system provides an effective method to recognize signals with different phase modulation formats, which is suitable for future dynamically reconfigurable optical networks.

All-optical matching structure for multi-order modulation formats

With the development and popularity of the Internet, network security has become a popular topic. The traditional solution for screening the security of network information is to convert the signal transmitted in the optical fiber into an electrical signal through an optical conversion. Then we perform symbol matching within the electronic firewall to determine whether the signal is a risk. However, due to the limitation of carrier recovery time in the semiconductor, the photoelectric converter cannot handle signals with too high rate, and it also causes a large power consumption. To improve the efficiency and scalability of signal matching, we propose an all-optical matching structure. This structure can identify the position of the target sequence in the input data sequence in the all-optical environment, and the structure is suitable for any amplitude and phase modulation format. The matching result of each bit of the target sequence and input data sequence is obtained by phase delay and interference. Then the matching result of each bit of the target sequence and input data sequence is integrated by logic AND gate, regenerator, and delay line. Finally, the matching result between the whole target sequence and the input data sequence is obtained. This structure can avoid photoelectric transformation and processes the signal directly at the optical domain, which greatly reduces the consumption of time and energy. We use VPItransmissionMaker software to simulate and verify the structure. The length of the input signal during the simulation is 8 bits, the length of the target signal is 4 bits, and the transmission rate of the signal is 100 GBaud. We simulated the binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 8-phase shift keying (8PSK), and 16 quadrature amplitude modulation (16QAM) modulation formats and analyzed the noise performance of the system. The results show that the structure can achieve all-optical matching of high-speed optical signals in BPSK, QPSK, 8PSK, and 16QAM modulation formats and has good anti-noise performance.

Analysis of a photonic integrated circuit for passive optical network for 5G NR.

This work presents the performance analysis of a passive optical network (PON) proposal with photonic integrated circuits (PIC). The PON architecture was simulated on MATLAB, focusing on the main functionalities of the optical line terminal, distribution network, and network unity regarded its effects on the physical layer. We show a simulated PIC, implemented on MATLAB through its analytic transfer function equation, used to implement orthogonal frequency division multiplexing in the optical domain to enhance the current optical networks for the 5G New-Radio (NR) scenario. We analyzed the OOK and optical PAM4 compared with phase modulation formats such as the DPSK and DQPSK. All modulation formats can be directly detected for the case in the study, simplifying the reception. Consequently, this work achieved a maximum symmetric transmission capacity of 1.2Tbps over 90km of standard single-mode fiber with 128 carriers, 64 carriers for downstream and 64 for upstream, obtained from an optical frequency comb with 0.3dB flatness. We concluded that phase modulation formats associated with PIC could increase PON capability and push further our current scenario to the 5G new era.

Novel Wide-Range Frequency Offset Estimation and Compensation for Burst-mode CPFSK Upstream Signaling in TDM-Based Digital Coherent PON

The burst-mode continuous phase frequency shift-keying (CPFSK) transmitter that combines a directly modulated laser diode, an electro absorption modulator and a semiconductor optical amplifier is attractive as a cost-effective transmitter for phase modulation formats for digital signal processing (DSP)-based coherent passive optical network (PON) upstream signaling. However, since highly accurate wavelength controllers for the transmitters in optical network units (ONUs) create excessive cost burdens, large carrier frequency offsets (CFOs) must be expected. Thus, a CFO compensation method with wide compensation range is required. This paper proposes a novel CFO estimation and compensation method for burst-mode CPFSK signals in upstream PON signaling. The proposed method is based on a simple blind algorithm and does not require any training symbols. We demonstrate wide CFO compensation range, from −12 to 14 GHz, with high receiver sensitivity, less than −42.5 dBm for 10 Gbit/s binary CPFSK signals. This range far exceeds that of the conventional CFO compensation method using a blind algorithm. Moreover, the proposed method can enhance the convergence of finite impulse response (FIR) filters. The feasibility of the proposed CFO compensation technique is successfully demonstrated for burst-mode CPFSK signals.

Frequency‐to‐voltage converter based dual‐loop phase‐locked loop with variable phase locking capability

A novel frequency-to-voltage converter based phase-locked loop (PLL) is proposed to overcome the inability of a frequency-to-voltage converter based frequency-locked loop to lock phase. The proposed dual-loop PLL adds variable phase-locking capability, such that the phase locking angle can vary from 0–360°. The additional variable phase-locking can be applied in data communication in the form of phase modulation. The design is targeted for a 0.5-μm CMOS process. The proposed design generates a 480 MHz clock from a reference clock of 15 MHz. In simulation, the proposed PLL locks within 3.56 μs while consuming 1.61 mW of power.

Interpolarization Forward Stimulated Brillouin Scattering in Standard Single‐Mode Fibers

AbstractForward stimulated Brillouin scattering in standard single‐mode fibers draws increasing interest toward sensing and signal processing applications. The process takes place through two classes of guided acoustic modes: purely radial ones and torsional‐radial modes with twofold azimuthal symmetry. The latter case cannot be described in terms of scalar models alone. In this work, the polarization attributes of forward stimulated Brillouin scattering in single‐mode fibers are investigated in analysis and experiment. Torsional‐radial acoustic modes are stimulated by orthogonally polarized pump tones, a first such report in standard single‐mode fibers. The scattering of optical probe waves by torsional‐radial modes may take up the form of phase modulation, cross‐polarization coupling, or a combination of both, depending on polarization. Lastly, this analysis predicts that circular and orthogonal pump tones may stimulate acoustic vortex beams: torsional‐radial modes that are rotating. The rotation represents the transfer of angular momentum between the polarization degree of freedom of the light field and the acoustic wave.

Performance analysis of differential quadrature phase shift keying modulation schemes for a radio over fiber system

Radio over fiber systems have become one of the best options for backhaul due to their larger bandwidth, low propagation loss, and competitive cost. Advanced modulation formats play a key role in enhancing the performance of fiber optic communication systems by providing higher bit rates and less susceptibility to noise in long distance transmission. This paper presents a detailed analysis of differential quadrature phase shift keying modulation in a radio over fiber system at 60 GHz for 5G applications. The differential quadrature phase shift keying modulation is combined with two different advanced phase modulation formats, i.e., return-to-zero and carrier suppressed return-to-zero to provide higher spectral efficiency. The performance of the system has been investigated at 10 and 20 Gbps data rates for 10 to 50 km transmission lengths of different types of fiber. Overall, it has been observed that carrier suppressed return-to-zero differential quadrature phase shift keying is better as compared with return-to-zero differential quadrature phase shift keying at both 10 and 20 Gbps data rates up to a transmission length of 50 km.

Highly Tunable Heterodyne Sub-THz Wireless Link Entirely Based on Optoelectronics

This article presents the experimental demonstration of a fully photonics-based heterodyne subterahertz (sub-THz) system for wireless communications. A p-i-n photodiode is used as a broadband transmitter to upconvert the signal to the sub-THz domain and a photoconductive antenna downconverts the received wave to an intermediate frequency around 3.7 GHz. The optical signals used for photomixing are extracted from two independent optical frequency combs with different repetition rates. The optical phase locking reduces the phase noise of the sub-THz signal, greatly improving the performance of the system when phase modulation formats are transmitted. The sub-THz carrier is tuned between 80 and 320 GHz in 40-GHz steps, showing a power variation of 21.8 dB. The phase noise at both ends of the communication link is analyzed and compared with the phase noise of the received signal with different wireless carriers. As a proof-of-concept, a 100-Mbit/s binary-phase-shift-keying signal is successfully transmitted over 80-, 120-, and 160-GHz carriers, achieving a bit error rate below 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> in the first two cases. These results show the great potential of THz communications driven by photonics to cover an extensive portion of the THz range without relying on electronic components that limit the operating range of the system to a concrete frequency band.

Design and evaluation of 2.3 Tb/s (23 ch. × 100 Gb/s) multi-carrier WDM optical transmission systems

Multilevel phase modulation formats with coherent detection enable a new generation of high speed optical transport platform. We demonstrate 23 × 100 Gbps (2.3 Tb/s) WDM Optical systems employing multicarrier generation concept. Three lasers are used to generate 23 sub-carriers using multicarrier generator at transmitter section. Each sub-carrier transmits at a transmission rate of 100 Gbps using polarization division multiplexed quadrature phase shift keying (PDM-QPSK) modulation format with spacing of 25 GHz between sub carriers. The analysis is carried out for 23 × 100 Gb/s (2.3 Tb/s) PDM-QPSK WDM optical systems with ultra large area fiber (ULAF), standard single mode fiber (SSMF) and large effective area fiber (LEAF) at transmission reach from 600 to 5000 km. Coherent detection with DSP is used for all the systems at receiving end. Systems are verified with parameters like symbol error rate, error vector magnitude (EVM) and Q-factor using analytical and simulation results. Improvement of 1.66 dB to 3.21 dB and 2.08 dB to 4.63 dB is noted in Q-factor for system with ULAF in comparison with system using SSMF and LEAF respectively over 600 km to 5000 km transmission reach. EVM values are found 2.24% to 2.68% and 2.68% to 12.43% lower in system with ULAF than system with SSMF and LEAF respectively. Log of estimated symbol error is observed less for system with ULAF than systems with SSMF and LEAF fibers, respectively, at transmission distance of 5000 km. The results clearly show that WDM optical system with ULAF fiber gives better performance.

Optical Power Budget Enhancement in 50–90 Gb/s IM-DD PONs With NOMA-CAP and SOA-Based Amplification

We report experimental results of a semiconductor optical amplifier (SOA) for optical amplification in a 50-90 Gb/s IM-DD optical access system using non-orthogonal multiple access multiplexing combined with multi-band carrierless amplitude phase modulation format (NOMA-CAP). Specifically, the SOA has been investigated as both booster and pre-amplifier for downstream applications in PONs. The measured optical power budgets resulting from performing booster amplification and pre-amplification simultaneously, assuming a BER threshold at $2.2\times 10^{-3}$ , are 28.7(23.7) dB and 23.6(18.9) dB at 50(90) Gb/s for the strong and weak NOMA levels, respectively, compared to the budgets for the strong and weak NOMA levels of 12.4(8.7) dB and 9.4(5.2) dB when no optical amplification is used.

Visible Laser Light Communication Based on LDPC-Coded Multi-Band CAP and Adaptive Modulation

In this paper, a multi-band carrierless amplitude and phase (CAP) modulation format based on a low-density parity-check (LDPC) code and an adaptive modulation is experimentally demonstrated in visible laser light communication (VLLC) for the first time. To achieve high spectral efficiency (SE) of the VLLC system, the effects of the LDPC code and adaptive modulation for the VLLC system are investigated. In addition, the relationship between SE and subcarrier m , where m = {1, 2, 4} with a total bandwidth of 862.5 MHz, is analyzed. The experimental results show that the optimal tradeoff between SE and bit error ratio (BER) performance is 64/64/64/16-quadrature amplitude modulation for 4-CAP system, with SE (net bit rate) of 3.56 b/s/Hz (3.08 Gb/s) under the BER of 10−3.

Optimization of Phase Modulation Formats for Suppression of Stimulated Brillouin Scattering in Optical Fibers

We theoretically investigate nonlinear optimization of periodic phase modulation for suppression of stimulated Brillouin scattering (SBS) in single-mode optical fibers. We use nonlinear multiparameter Pareto optimization to find modulations that represent the best tradeoff between SBS and optical linewidth, as measured by its rms value. The optimization uses a temporal-amplitude-domain finite-difference Brillouin solver with noise initiation to find the best phase modulation patterns in the presence of coherent so-called cross-interactions. These can be important in short fibers, when the period is large enough to make the frequency-domain separation of the modulated signal comparable to, or smaller than, the Brillouin gain linewidth. We calculate the SBS threshold for the optimized modulation patterns and find that smaller spectral line spacing improves the SBS threshold for the same linewidth. By contrast, whereas the maximum modulation depth and modulation frequency influence the range of accessible linewidths, they do not significantly alter the threshold for a given linewidth. We investigate the dependence on fiber length and find that while shorter fibers have a higher threshold, the increase is smaller than the often-assumed inverse dependence on length. Furthermore, we find that optimized formats are superior in terms of SBS threshold as well as in terms of linewidth control, compared to random modulation.

Waveguide Integrated Balanced Photodetectors for Coherent Receivers

This paper presents a brief review of waveguide integrated balanced photodetectors for coherent receivers and describes some of their recent progresses. Waveguide integrated balanced photodetectors and balanced photodiodes (PD) monolithically integrated to InP-based coherent receiver photonic integrated circuits (PIC) are discussed. On one hand, the devices focus on high-end market for long-haul transmission, and on the other hand on short reach transmission for data centers. In this paper, also a balanced photodetector with the highest ever reported 3-dB bandwidth of 115 GHz is demonstrated. Moreover, a low-power concept for a homodyne receiver PIC with balanced avalanche PD is emphasized to introduce phase modulation formats to data center transmissions.

A Carrierless Amplitude Phase (CAP) Modulation Format: Perspective and Prospect in Optical Transmission System

The explosive demand of broadband services nowadays requires data communication systems to have intensive capacity which subsequently increases the need for higher data rate as well. Although implementation of multiple wavelengths channels can be used (e.g. 4 × 25.8 Gb/s for 100 Gb/s connection) for such desired system, it usually leads to cost increment issue which is caused by employment of multiple optical components. Therefore, implementation of advanced modulation format using a single wavelength channel has become a preference to increase spectral efficiency by increasing the data rate for a given transmission system bandwidth. Conventional advanced modulation format however, involves a degree of complexity and costly transmission system. Hence, carrierless amplitude phase (CAP) modulation format has emerged as a promising advanced modulation format candidate due to spectral efficiency improvement ability with reduction of optical transceiver complexity and cost. The intriguing properties of CAP modulation format are reviewed as an attractive prospect in optical transmission system applications.

A Tunable Single Passband Microwave Photonic Filter of Overcoming Fiber Dispersion Induced Amplitude Fading

A tunable single passband microwave photonic filter (MPF) of overcoming fiber dispersion induced amplitude fading of the microwave passband is proposed and demonstrated. The passband amplitude of the MPF can be kept invariant for different central frequencies. The scheme is realized based on a dual-drive Mach–Zehnder modulator (DDMZM) and a broadband optical source sliced by a delay interferometer. The DDMZM is single-electrode driven and the microwave signal is modulated onto the optical carrier with simultaneous phase and intensity modulation formats. The ratio of the two modulation formats can be controlled by adjusting the bias of DDMZM to compensate the dispersion-induced amplitude fading at any passband of the MPF. In the experiment, the proposed MPF can be tuned between 0 and 30 GHz and the rejection ratio exceeds 30 dB.

Performance Evaluation and Nonlinear Mitigation through DQPSK Modulation in 32 × 40 Gbps Long-Haul DWDM Systems

AbstractHigher spectral efficiency and greater data rate per channel are the most cost-effective strategies to meet the exponential demand of data traffic in the optical core network. Multilevel modulation formats being spectrally efficient enhance the transmission capacity by coding information in the amplitude, phase, polarization or a combination of all. This paper presents the design architecture of a 32-channel dense wavelength division multiplexed (DWDM) system, where each channel operates with multi-level phase modulation formats at 40 Gbps. The proposed design has been simulated for 50 GHz channel spacing to numerically compute the performance of both differential phase-shift keying (DPSK) and differential quadrature phase-shift keying (DQPSK) modulation formats in such high-speed DWDM system. The transmission link is analyzed with perfect dispersion compensation and also with under-compensation scheme. The link performance in terms of quality factor (

Low-cost bidirectional hybrid fiber-visible laser light communication system based on carrier-less amplitude phase modulation

We propose a bidirectional hybrid fiber-visible laser light communication (fiber-VLC) system. To reduce the cost of the system, the cheap and easy integration red vertical cavity surface emitting lasers, low-complexity carrier-less amplitude phase modulation format, and wavelength reuse technique are utilized. Meanwhile, the automatic gain control amplifier voltage and bias voltage for downlink and uplink are optimized. The simulation results show that, by using the proposed system, the bit error rate of 3.8×10−3 can be achieved for 16-Gbps CAP signal after 30-km standard single mode fiber and 8-m VLC bidirectional transmission. Therefore, it indicates the feasibility and potential of proposed system for indoor access network.

Performance measurements on NIF beamlines for future experiments to support polar direct drive

We are studying the implementation of polar direct drive (PDD) ignition experiments on the National Ignition Facility (NIF) laser system. Part of this preparation involves testing the performance of the NIF laser system over a broader span of center wavelengths, 3.6 nm, where the laser currently operates and that gain models describe. The temporal shape for the PDD pulses consists of a drive pulse preceded by three lower power “picket pulses”. These picket pulses require a multi-FM sinusoidal phase modulation format with a bandwidth of ∼ 200 GHz and a more dispersive grating in the preamplifier module (PAM) for smoothing-by-spectral-dispersion (SSD). In this paper we discuss recent measurements of gain on the NIF laser system over this broader wavelength range. We measured FM-to-AM conversion over the 3.6 nm wavelength range. The possibility of pinhole closure due to the larger bandwidth and dispersion associated with multi-FM SSD was studied at LLE on the OMEGA EP laser.

System Performance and Limits of Optical Modulation Formats in Dense Wavelength Division Multiplexing Systems

In this paper we investigate in OptSim software environment the system performance of intensity and phase modulation formats for different network scenarios and dense wavelength division multiplexing grids. OptSim employs the Time Domain Split Step method to implement the signal distribution equation in a fiber. We investigate intensity formats, such as Non Return to Zero, Return to Zero, Carrier-Suppressed Return to Zero and DuoBinary, and phase modulation formats like Differential Phase-Shift Keying and Differential Quadrature Phase-Shift Keying. The main goal is to compare these formats in terms of bit error rate, Q-factor, optical reach and grid limitations for transmission rates 10, 40 and 100 Gbps per channel and discuss the possibilities of increasing their spectral efficiency. We also focus on other advanced solutions such as the polarization division multiplexing combined with phase modulations, coherent detection and advanced digital signal processing which mainly benefits in spectral efficiency, optical signal to noise ratio and chromatic dispersion tolerances. DOI: http://dx.doi.org/10.5755/j01.eie.22.2.9599