Fig. 1. Schematic diagram of sampling performance test of SCF fan-out module. (a) The cross section of SCF. (b) The sampling result of SCF fan-out module. (c) The experimental device diagram for testing the sampling capacity of SCF fan-out module. SCF: seven-core fiber. CCD: charge-coupled device.

Fig. 2. Schematic diagram of STML laser and SCF-SMS. Pump: 980 nm laser diode. WDM: wavelength division multiplexer. LPFG: long-period fiber grating. L1, L2, L3: lenses. M1, M2, M3: mirrors. HWP: half-wave plate. QWP: quarter-wave plate. BS: beam splitter. PD-ISO: polarization-dependent isolator. SF: spectral filter. ODL: optical delay line. OC: optical coupler. DCF: dispersion compensating fiber. PD: photodetector.

Fig. 3. The basic characteristics of spatiotemporal mode-locking. (a) The spectrum. (b) Time domain pulses. (c) The RF spectrum. (d) The light fields (the black triangular markers correspond to the two acquisition channels).

Fig. 4. (a) The comparison of average spectra by spectrometer between two channels. (b) The comparison of average spectra by spectrometer and evolution spectra by TS-DFT in channel II.

Fig. 5. The transient establishment dynamics of spatiotemporal mode-locking within two channels. (a) The transient establishment data acquired from two channels by time-division multiplexing. The black solid and dashed lines delineate the four stages in the establishment process of spatiotemporal mode-locking: (i) Q-switching, (ii) beating dynamics, (iii) spatiotemporal soliton state transition dynamics, and (iv) stable dual-soliton. (b) Two-dimensional contour map of accumulated data ranging over 10,000 roundtrips (the pulses outside the white dashed box are the higher-order mode pulses due to the 1030 nm laser injection into the 1550 nm stretched fiber, which do not affect the evolutionary characteristics of the STML buildup process, so we have ignored this part in the subsequent studies). (c), (d) The enlarged details within the white dashed box in (b), and the white dashed line also marks the four stages. (e) The average mapping spectrum of two channels within stage iv. (f) The detailed diagram of the Q-switching process. (g), (h) The total energy evolution corresponding to two channels. The inset shows the enlarged energy variation during stage ii (indicated by the black dashed rectangle).

Fig. 6. The beating dynamics of spatiotemporal mode-locking. (a) The evolution of two-dimensional contour map of beating dynamics process. (b), (c) The beating dynamic enlarged details of channels II and VII. (d) The single-shot spectra of hybrid mode pulses i and ii at the white dashed line markers. (e) The single-shot spectra of hybrid mode pulses iii and iv at the white dashed line markers (the purple dashed box was used to compare the pulse details).

Fig. 7. Spatiotemporal soliton state transition dynamics of spatiotemporal mode-locking. (a) The slice evolution of spatiotemporal soliton state transition during the process of establishing spatiotemporal mode-locking. (b), (c) The detail display of the white dashed box in (a). (d) The single-cycle evolution spectrum marked by white dashed line markers in (b). (e) The single-cycle evolution spectrum marked by white dashed line markers in (c) (the blue dashed box was used to compare the pulse details).

Fig. 8. The slice evolution of pulsation soliton in detail. (a) The slice evolution of pulsation behavior of channel II from RT5800 to RT5840. (b) The slice evolution of pulsation behavior of channel VII from RT5800 to RT5840. (c) The overall energy evolution of four hybrid mode pulses during pulsation. (d) The energy details in the black dashed box in (c).

Fig. 9. The phase-space of the intensities and phases at fixed points in the autocorrelation for each roundtrip of four hybrid mode pulses during spatiotemporal soliton state transition dynamics.