Analytic study on triple-S, triple-triangle structure interactions for solitons in inhomogeneous multi-mode fiber

Dark soliton control based on dispersion and nonlinearity for third-order nonlinear Schrödinger equation

In the long-distance optical fiber communication system, we consider the (3+1)-dimensional coupled nonlinear Schrodinger equation with perturbation functions, which controls the transverse effects, because of the complexity of nonlinear phenomena. Anti-dark two-soliton solutions are derived by the Hirota method. The perturbation function representing the dissipation rate is discussed. Five different transmission structures of solitons are presented. Besides, their propagation and collision dynamics are analyzed. Control methods for phase shift and oscillation are also suggested. We hope results in this paper are of guiding significance to the research of phase shifters, optical logic devices and ultrashort pulse lasers.

Phase shift, oscillation and collision of the anti-dark solitons for the (3+1)-dimensional coupled nonlinear Schrödinger equation in an optical fiber communication system

Analytic study on the influences of higher-order effects on optical solitons in fiber laser

Crack detection on metallic surfaces is important for the inspection of critical metallic devices. In this paper, a high-sensitivity near-field waveguide sensor loaded with a dielectric resonator for metallic crack detection is demonstrated. Both the numerical and experimental results reveal that this dielectric resonator-based waveguide sensor can effectively detect cracks on a metallic surface. The maximum depth sensitivity is 0.71 GHz/mm and the maximum width sensitivity is 1.24 GHz/mm, resulting from the localized electric field energy on the dielectric resonator in the broad side of the waveguide sensor. This work will be of interest to the development of metallic crack detection and related applications.

High-Sensitivity Dielectric Resonator-Based Waveguide Sensor for Crack Detection on Metallic Surfaces

An optically controlled system for generating and continuously steering radio frequency (RF) signals with double orbital angular momentum (OAM) modes is proposed and experimentally demonstrated. The optical carrier’s utilization efficiency can be doubled through the distinct electro-optical modulation, which is based on two single-sideband modulation operations on a single optical carrier through a customized dual-parallel Mach–Zehnder modulator. A constructive antenna phase feeding method of a circular antenna array for collectively forming and steering an OAM radio beam is proposed and illustrated. A proof-of-concept experiment is conducted to generate and steer a dual-mode RF-OAM beam to two different two-dimensional (2D) directions, independently and simultaneously. One 17 GHz OAM beam with mode L=1 is continuously steered to 2D directions (:, 0°, 0°), (:, 0°, 1.70°), (:, 0°, 3.87°), (:, 0°, 6.17°), and(:, 0°, 7.80°), with vortex properties, where “:” means “any value of.” Meanwhile, the 19 GHz OAM beam with mode L=−1 carried is steered from (:, 0°, 0°) to (:, 0°, −6.72°), and the constellations are obtained successfully.

2D optically controlled radio frequency orbital angular momentum beam steering system based on a dual-parallel Mach-Zehnder modulator.

Misalignment measurement is important in radio frequency orbital angular momentum (RF-OAM)-related communication and radar applications. Misalignment causes distorted vortex wavefront and OAM spectra dispersion, therefore a conventional gradient method cannot be used directly. We propose a misaligned measurement method for RF-vortex beams based on image processing. Theoretical analysis and numerical simulations of the misaligned OAM wavefront demonstrate that the misalignment information can be measured by extracting the features of the OAM mean value distribution and the OAM variance value distribution. It is found in this paper that the extrema of mean OAM distribution and OAM variance distribution correspond to the tilted singularity point and original pivot point, separately. These extrema points can be found by image processing algorithms that recognize round speckles. A proof-of-concept experiment is presented, which employs a 2-D scanning probe to measure a 10°-tilted OAM beam with mode +1. The tilt measurement error is only 0.39°.

Misalignment Measurement of Orbital Angular Momentum Signal Based on Spectrum Analysis and Image Processing

A photonics system for baseband-free arbitrary-phase-coded microwave waveform pulse (APCMWP) generation is proposed and demonstrated. The proposed system realizes the generation of APCMWP, and further solves the baseband components problem in the pulsed process. The system uses a polarization-multiplexing dual-drive Mach–Zehnder modulator (PM-DMZM) and an optical band pass filter (OBPF) to obtain a polarization-multiplexed single-sideband modulated (SSBM) optical signal with carrier intensity-phase modulation, then uses a balanced photodetector (BPD) to properly detect the polarization-multiplexed SSBM optical signal, APCMWP with baseband components suppression can be easily generated. A detailed theoretical analysis and a proof-of-concept experiment are provided. The generations of 1.2-GBaud 9.6-GHz and 2-GBaud 12-GHz baseband-free APCMWP are verified.

Photonics Generation of Baseband-Free Arbitrary-Phase-Coded Microwave Waveform Pulse

An analog photonic link (APL) based on a dual-polarization dual-parallel Mach–Zehnder modulator (DP-DPMZM) is proposed and experimentally demonstrated. The proposed APL can suppress the nonlinearity of modulator, compensate the power fading induced by dispersion (PFID), and improve the power efficiency of link, leading to large dynamic range. The PFID and the nonlinearity are suppressed by adjusting the phase of optical carrier (OC) and polarization controller (PC), respectively. In addition, by optimizing the optical carrier to sideband ratio (OCSR) in the DP-DPMZM, the output RF power and the power efficiency of link can be significantly improved while the total optical power received by the photodetector (PD) remains constant. An experiments are performed to demonstrate the feasibility of the APL. The results show that an spurious free dynamic range (SFDR) of 103.2 dB·Hz4/5 for 13.73 GHz is achieved after compensating PFID and nonlinearity, which is 32 dB higher than that of a conventional double sideband (DSB) assisted APL. After OCSR optimizing, the output RF power achieves 13-dB improvement, and the SFDR is further raised to 114.1 dB·Hz4/5.

High Power Efficiency and Dynamic Range Analog Photonic Link with Suppressed Dispersion-Induced Power Fading

A wideband microwave photonic phase shifter (MPPS) based on a dual-polarization dual-parallel Mach–Zehnder modulator (DP-DPMZM) is proposed and experimentally demonstrated. The proposed system has the features of chromatic dispersion (CD) immunity and tunable optical carrier to sideband ratio (OCSR), which can realize long fiber transmission distance with improved power efficiency. It is realized by carrier suppress double sideband (CS-DSB) plus optical carrier (OC) modulation at two orthogonal polarization states. The phases of output RF signals can be tuned continuously and independently by controlling the phases of the OCs. The experiment results show that the continuous 360° phase shifts of output RF signal over 5–25 GHz are both realized in the cases of back-to-back and fiber transmission. No CD-induced power fading and phase severe shaking of the RF signals appear after the dispersion compensating fiber (DCF) of −331 ps/nm at 1545 nm transmission. By optimizing the OCSR of the system, the output RF power efficiency of the proposed scheme realizes significantly improvement when input RF powers and output optical powers are both fixed. The possibility of generating frequency doubling signal is also verified.

Xiyao Song

Papers

2D optically controlled radio frequency orbital angular momentum beam steering system based on a dual-parallel Mach-Zehnder modulator.

Misalignment Measurement of Orbital Angular Momentum Signal Based on Spectrum Analysis and Image Processing

Photonics Generation of Baseband-Free Arbitrary-Phase-Coded Microwave Waveform Pulse

High Power Efficiency and Dynamic Range Analog Photonic Link with Suppressed Dispersion-Induced Power Fading

Wideband and Dispersion Immune Microwave Photonic Phase Shifter With Tunable Optical Carrier to Sideband Ratio