The nonlinearity of a transmission fiber may be compensated by a specialty fiber and an optical phase conjugator. Such combination may be used to pre-distort signals before each fiber span so to linearize an entire transmission line.
Record-Breaking 1935.6 bit/s/Hz Spectral Efficiency in 19-Ring-Core Fiber Transmission of GMI-Estimated 25.24 Pb/s Capacity Using Low-Complexity 4x4 MIMO
Nonlinear Inference Capacity of Fiber-Optical Extreme Learning Machines
Leibniz-Institute of Photonic Technology(莱布尼茨光子技术研究所);Institute of Physical Chemistry, Friedrich Schiller University Jena(耶拿弗里德里希·席勒大学物理化学研究所);Institute of Applied Optics and Biophysics, Friedrich Schiller University Jena(耶拿弗里德里希·席勒大学应用光学与生物物理学研究所)
Compensation of nonlinear phase shifts with third-order dispersion: fiber stretchers can out-perform grating stretchers in short-pulse fiber amplifiers
We report the experimental observation of SOP scattering in Stokes space caused by nonlinear depolarization (NLDP) of light in fiber. In addition to our previous characterizations of NLDP by SOP speed histograms and Stokes vector spectra, we measure SOP scattering angles. For trans-Pacific propagation distances these angles range within a few degrees.
Research on multimode optical fibers is arousing a growing interest, for their capability to transport high-power laser beams, coupled with novel nonlinear optics-based applications. However, when beam intensities exceed a certain critical value, optical fiber breakdown associated with irreversible modifications of their refractive index occurs, triggered by multiphoton absorption. These processes have been largely exploited for fiber material microstructuration. Here we show that, for intensities slightly below the breakdown threshold, nonlinear absorption strongly affects the dynamics of a p…
We study the coherence characteristics of light propagating in nonlinear graded-index multimode fibers after attaining optical thermal equilibrium conditions. The role of optical temperature on the spatial mutual coherence function and the associated correlation area is systematically investigated. In this respect, we show that the coherence properties of the field at the output of a multimode nonlinear fiber can be controlled through its optical thermodynamic properties.
We theoretically and experimentally demonstrate a novel mode-locked ytterbium-doped fiber laser with a saturable absorber based on nonlinear Kerr beam cleanup effect. The saturable absorber was formed by a 2-m graded-index multimode fiber and a single-mode fiber segment served as a diaphragm. With an all-normal-dispersion-fiber configuration, the laser generated dissipative soliton pulses with pulse duration of 26.38 ps and pulse energy more than 0.25 nJ; output pulses could be compressed externally to 615.7 fs. Moreover, the self-starting mode-locking operation of this laser exhibited a high …
Nonlinear propagation of signals in single-mode fiber is well understood, and is typically observed by measuring the temporal profile or optical spectrum of an emerging signal. In multimode fibers, the nonlinearity has both a spatial and a temporal element, and a complete investigation of the interactions between propagating modes requires resolving the output in both space and time. We report here spatiotemporal measurements of two nonlinear interacting LP$_{0m}$ modes of a step-index few-mode fiber (FMF). We describe a method to selectively excite two propagating modes through the use of a p…
We experimentally investigate a nonlinear switching mechanism in a dual-core highly nonlinear optical fiber. We focus the input beam of femtosecond pulses on one core only, to identify transitions between inter-core oscillations, self-trapping in the cross core, and self-trapping of the pulse in the straight core. A model based in the system of coupled nonlinear Schrodinger equations provides surprisingly good agreement with the experimental findings.
Multimode fiber systems are desirable for industrial and scientific applications. As an interesting effect for the laser beam propagation in a multimode fiber, nonlinear Kerr beam cleanup has attracted considerable research interest due to the spatial beam compressing. However, its physical mechanisms, especially the influences of input conditions on its performances, remain unclear. Here, we report a new self-organized regime for the multimode beam propagation in a graded-index multimode fiber: when the input laser has a dominant mode in which most of the laser energy is concentrated, the bea…
We propose a nonlinear fiber system for shot-noise limited, all-optical intensity-noise reduction and signal amplification. The mechanism is based on the accumulation of different nonlinear phase shifts between orthogonal polarization modes in a polarization-maintaining fiber amplifier in combination with an implemented sinusoidal transmission-function. The resulting correlation between the input intensity-fluctuations and the system transmission enables tunable intensity noise reduction of the input pulse train. In the experiment, the noise spectral density of a mode-locked oscillator is supp…
The characterization of the complex spatiotemporal dynamics of optical beam propagation in nonlinear multimode fibers requires the development of advanced measurement methods, capable of capturing the real-time evolution of beam images. We present a new space-time mapping technique, permitting the direct detection, with picosecond temporal resolution, of the intensity from repetitive laser pulses over a grid of spatial samples from a magnified image of the output beam. By using this time-resolved mapping, we provide the first unambiguous experimental observation of instantaneous intrapulse non…
In this work, we investigate the steady-states of a fiber lasers mode-locked with a nonlinear amplifying loop-mirror that has an inherent amplitude noise-suppression mechanism. Due to the interaction of the sinusoidal transmission function with the fluctuating intracavity pulse amplitude we show that this mechanism may lead to a detectable difference in relative intensity noise at the reflected and transmitted output port under specific preconditions. We present systematic intensity noise measurements with a nonlinear fiber-based system that replicates a single roundtrip in the laser cavity. E…