Recent Advances in Nonlinear Dynamics of Fiber Lasers and Amplifiers at Near-Infrared Spectrum

Abstract

Fiber lasers and amplifiers operating in the near-infrared III (NIR-III) spectral region, approximately 1550–1870 nm, are increasingly important for biomedical imaging, spectroscopy, optical communications, sensing, and advanced photonic systems because this wavelength range combines reduced scattering, useful tissue penetration, and compatibility with mature telecom-band fiber technology. However, direct ultrafast generation across the full NIR-III window remains difficult because erbium-, thulium-, holmium-, and bismuth-based gain media provide only fragmented gain coverage, limited efficiency, or restricted pulse-energy scaling. This review therefore focuses on how third-order nonlinear mechanisms in optical fibers overcome these gain limitations by shifting, broadening, and parametrically converting pulses from convenient pump wavelengths into the NIR-III region. Unlike general treatments of nonlinear fiber optics, the emphasis here is on NIR-III-specific design constraints: dispersion and phase matching near 1.55–1.9 um. Raman red-shift pathways from telecom-band sources, coherence and noise requirements for biomedical imaging, and the trade-off between tunability, pulse duration, spectral power density, and system complexity. Self-phase modulation, four-wave mixing, stimulated Raman scattering, soliton self-frequency shift, and supercontinuum generation are reviewed and compared using practical performance metrics, including wavelength coverage, pulse duration, output power, pulse energy, efficiency, coherence, and implementation complexity. The review concludes by identifying key opportunities in large-mode-area, hollow-core, and dispersion-engineered fibers, as well as hybrid gain-nonlinear architectures for stable, efficient, and application-driven NIR-III fiber sources.

Received: 3 February 2026 | Revised: 30 June 2026 | Accepted: 23 September 2026

Conflicts of Interest

The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Author Contribution Statement

Opeyemi Akanbi: Conceptualization, Writing – original draft, Supervision. Boluwatife Oluwasegun: Investigation, Writing – review & editing. Quadri O Adewuyi: Resources. Joshua Ejeka: Writing – original draft. Augusta Imomon: Writing – review & editing. Adetola Hassan-Kuti: Visualization. Adetoun Oginni: Writing – review & editing, Supervision. Enoch Nii-Okai: Visualization, Project administration. Michael Adelere: Investigation, Resources. Rebecca N Joshua: Investigation, Resources.