Search

Optical interferometry is a promising alternative for acoustic detection as it records the changes of interference patterns. Apart from interferometric sensor heads, readout systems also play a crucial role in sensing performance. Here, inspired by the soliton molecule vibrations in ultrafast lasers, we introduce an efficient real-time spectral interferometry (RSI) approach to read out the Fabry–Pérot interferometer (FPI) for acoustic detection. Broadband pulses, emitted from an ultrafast fiber laser, are launched into the FPI sensor. Pseudo dual-pulse molecule is constructed by virtue of the equivalent two-beam interference of the FPI and modulated by the diaphragm transducer. The acoustic driven "molecular vibration" conforms to the sound applied on the metal diaphragm. Hence, the acoustic signals can be directly recorded by the successive dual-pulse spectral interferograms, imaged as a spectral encoded "soundtrack." We experimentally achieve the real-time characterization of both the audible and ultra sounds by retrieving the relative phase evolutions with a phase resolution of 37.6 mrad and preliminarily verifying the feasibility of the RSI in acoustic detection. This approach to wideband acoustic detection highlights an advanced application of ultrafast laser sources and paves an efficient way for interrogating the interferometric fiber sensors. [ABSTRACT FROM AUTHOR]

The self-assembly of optical solitons propagating in nonlinear dissipative systems spreads the concept of soliton molecules. Assisted with the real-time spectral interferometry, plentiful internal dynamics has been probed within the multi-pulse patterns, emphasizing the striking analogies with the matter molecules. Therefrom, these particle-like behaviors would yield more intriguing landscapes toward the extended degrees of freedom considering increased constituents. Here, we transfer the concept of "isomer" to the experimental investigation on the unexplored isomeric dynamics of soliton molecules in parallel. Particularly, two isomers for soliton triplets and four isomers for soliton quadruplets are captured under different self-assembled forms, within each of which the binding separations and relative phases of the constituents are governed by mutual soliton interactions. With the diverse separation-phase evolving trajectories mapped in the interaction plane, detailed insights into the temporal distribution and the transient dynamics are displayed with respect to a panorama of the isomeric dynamics. The perspective of optical isomers shed new light on the analogy with matter molecules, and the underlying isomeric dynamics may stimulate the artificial manipulation of various soliton molecules for ultrafast applications. [ABSTRACT FROM AUTHOR]

• Passively mode-locked fiber laser. • Time-stretch dispersion Fourier transform. • Internal dynamics and temporal distributions of tri-pulse structures. • Polarization and gain control. • Manipulation mechanism on internal dynamics. Self-assembly of ultrashort pulses highlights the complex patterns of dissipative solitons, termed soliton molecules in consideration of the particle-like behaviors. Multi-constituent temporal patterns release the degrees of freedom of versatile internal motions, emphasizing the molecular-analogous soliton dynamics and the advanced laser applications. Beyond previous studies, exploring the artificial manipulation of the intra-molecular dynamics would spread a new research horizon of ultrafast science. Here, we report the research on the manipulation mechanism on the internal dynamics under a tri-soliton model via the implementation of the polarization and gain control. Assisted with real-time spectral interferometry, both the binding separations and the relative phases are retrieved to unfold the intra-molecular dynamics of soliton triplets. Particularly, we present the switching among tri-soliton states identified by different binding separations and phase-evolving velocities, and further unveil the universal rules of the internal dynamics. All these findings provide an evident manifestation of the artificial manipulation on the temporal distributions and intra-molecular dynamics, as well as enable promising access to rapid multi-pulse reconfiguration applicable to fiber laser platforms. [ABSTRACT FROM AUTHOR]

Ultrafast fiber laser as a dissipative nonlinear system is capable of generating various dynamical soliton molecules, providing an abundant platform for investigating the transient soliton dynamics. Here, we report on the real-time internal motions of harmonically mode-locked soliton molecules (HMLSMs) in a passively mode-locked fiber laser with nonlinear polarization rotation (NPR). Assisted with time-stretch dispersive Fourier transform (DFT), various real-time scenarios towards multi-pulse states are revealed. Particularly, both the stationary and evolving HMLSMs are respectively observed, indicating that each soliton molecule in one roundtrip possesses identical intra-molecular motions. These vivid internal motions are mainly dominated by the underlying interactions and energy flow between the adjacent constituents. All these findings provide an intriguing perspective in dynamical intra-molecular evolution of ultrafast nonlinear phenomena and further enrich the research of fundamental science. • Various mode-locking states certify the harmonic mode-locking mechanisms. • Stationary and evolving soliton molecules reveal transient soliton dynamics. • Inherent similarity of harmonically mode-locked soliton molecules. [ABSTRACT FROM AUTHOR]

Rapid progress in multi-state pulse generation spreads a new concept of multiplexed fiber laser. The investigations of laser designing and nonlinear soliton dynamics accelerate the discovery with respect to vivid working regimes of ultrashort pulsed lasers, as well as extending the potential application scenarios. Here, we report on the formation of multi-state solitons in a dual-wavelength mode-locked fiber laser. Attributing to the nonlinear polarization rotation (NPR) induced birefringence filtering effect inside the cavity, the fiber laser approaches dual-wavelength working regime, which simultaneously delivers modulation-instability (MI) solitons and conventional solitons in different wavebands. In particular, MI soliton singlets and conventional soliton molecules can be respectively emitted from these two lasing wavebands with asynchronous repetition rates. The soliton molecules exhibit various assembling forms with different bound-pulse number and pulse separations. The findings highlight the feasibility of multi-state soliton generation via waveband multiplexing and bring insight into various behaviors of soliton molecules. • Multi-state soliton generation based on waveband multiplexing with different pulse properties. • Various soliton compounds with manipulable multi-pulse structures. • 'Mapping' relationship unveils multi-pulse distribution. [ABSTRACT FROM AUTHOR]