Observation of High-Order Polarization-Locked Vector Solitons in a Fiber Laser

We report on the experimental observation of a new type of polarization-locked vector soliton in a passively mode-locked fiber laser. The vector soliton is characterized by the fact that not only are the two orthogonally polarized soliton components phase-locked, but also one of the components has a double-humped intensity profile. Multiple phase-locked high-order vector solitons with identical soliton parameters and harmonic mode locking of the vector solitons were also obtained in the laser. Numerical simulations confirmed the existence of stable high-order vector solitons in the fiber laser.

Figure 1

Schematic of the vector soliton fiber laser. WDM: Wavelength division multiplexer. EDF: Erbium-doped fiber.

Figure 2

Polarization resolved soliton spectra and autocorrelation traces of the vector soliton observed. (a) Soliton spectra. (b) Autocorrelation traces.

Figure 3

Oscilloscope trace of a harmonically mode-locked high-order phase-locked vector soliton state. Lc: Cavity round-trip time. Eight vector solitons coexist in the cavity.

Figure 4

A stable high-order phase-locked vector soliton state numerically calculated. (a) Soliton intensity profiles of the two orthogonally polarized components. (b) The corresponding optical spectra of (a).