Spatiotemporal mode-locking and dissipative solitons in multimode fiber lasers

a, Schematic diagram of dissipative soliton formation in SMF lasers and MMF lasers. b, An illustration of a typical STML MMF laser structure. c, Pulse reactions for 3 mechanisms as intermode dispersion will increase.

A proposed system to characterize STDSs.

a, Multimode nonlinear frequency conversion in STML lasers. b, Multimode achieve engineering. c, Multimode frequency combs. d, Intracavity management and multicore STML lasers.

CHINA, November 1, 2023 /EINPresswire.com/ — Multimode fiber (MMF) lasers could be invaluable for varied purposes, together with high-energy pulse technology, precision measurement, and nonlinear microscopy. In addition they function an excellent testbed for nonlinear spatiotemporal physics. The technology of ultrashort pulses in nonlinear multimode resonators depends upon spatiotemporal mode-locking (STML), which includes synchronization in each spatial and temporal dimensions. This overview focuses on the basics of STML, with a selected emphasis on the dynamics underneath massive intermode dispersion. Current progresses in spatiotemporal measurement methods, unique nonlinear dynamics of spatiotemporal dissipative solitons (STDS), and spatial mode engineering in MMF lasers are lined. We additionally present an outlook on future views for STML.

The delivery of spatiotemporal mode-locking (STML) can date again to the report of Wright et al., in 2017. Following this breakthrough, analysis on STML has thrived. Nevertheless, our comprehension and management of spatiotemporal dissipative solitons (STDSs) and STML in multi-mode fiber (MMF) lasers are usually not as mature as these in single-mode fiber lasers. Among the key challenges embody attaining ultrahigh pulse power and arbitrary mode profiles in MMF lasers and refining spatiotemporal characterization methods. Tackling these challenges would unlock numerous purposes for MMF lasers.

Not too long ago, a overview article entitled “Spatiotemporal mode-locking and dissipative solitons in multimode fiber lasers” was printed in “Gentle: Science & Functions” by the crew led by Changxi Yang and Chengying Bao from Tsinghua College, China. This overview summarizes the analysis progress on STML and STDS in MMF lasers and outlines a number of views which will carry breakthroughs for STML lasers.

Balancing intermode dispersion and synchronizing mode-resolved pulses are a prerequisite for STML. Relying on the magnitude of intermodal dispersion, three dominant mechanisms contributing to balancing intermode dispersion and govern STML: Kerr nonlinear dominant regime, spatiotemporal saturable absorber dominant regime, and spatial coupling dominant regime (Fig. 1b). Every regime reveals distinct dynamics for the three-dimensional pulses. These STDSs differ from typical ones with mounted pulse shapes as a result of advanced spatiotemporal coupling nature affecting their temporal, spectral, and spatial traits (Fig. 1c).

Multi-dimension measurement methods and nonlinear dynamics. – Measurement is important for understanding STDS behaviors. Presently, spectral filtering and spatial sampling can hardly seize the total dynamics of STDSs and hinders our capacity to manage STML lasers. Actual-time, multi-dimensional optical area measurements are essential to understand spatiotemporal dynamics. Combining methods like multimode dispersion Fourier remodel, time lenses, mode decomposition, and timing jitter measurements could make a strong system to characterize spatiotemporal dynamics of STDSs (Fig. 2). With full characterization of STDSs in spatial, temporal, and spectral dimensions, extra unique nonlinear dynamics could be captured and STML dynamics could be revealed.

Mode engineering and power scaling. – Mode area management and wavefront shaping have versatile purposes. Nevertheless, customizing mode parts in multimode lasers stays difficult. Beam self-cleaning, or introducing spatial mild modulators could allow mode area management of STML lasers. Attaining excessive pulse power with user-defined mode profile can open the door for a lot of thrilling purposes together with nonlinear microscopy. Furthermore, spatial coherence could add new prospects for purposes (e.g., chaotic Lidar) the place low coherence could be a bonus.

This part covers the purposes and novel technological pathways of spatiotemporal mode-locked lasers (Fig. 3). Subjects embody multimode optical frequency combs, wavelength-division multiplexing for multimode lasers, technology of multimode supercontinuum, mode-locked single-cavity twin/multi-combs, and coherently-pumped multimode lasers. These advances can push our capacity to manage photons in loosely confined, multi-mode, nonlinear, ultrafast methods to a brand new stage.

DOI
10.1038/s41377-023-01305-0

Unique Supply URL
https://doi.org/10.1038/s41377-023-01305-0

Funding info
This work is supported by the Nationwide Pure Science Basis of China (NSFC) (61975090, 62175127), by the Tsinghua College Initiative Scientific Analysis Program (20211080080, 2022108006), and by the Tsinghua-Toyota Joint Analysis Fund. The authors declare no conflicts of curiosity.

Lucy Wang
BioDesign Analysis
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