Mode-Locked All-Fiber Laser Emitting Two-Color High-Order Transverse Mode

We demonstrate that the mode-locked all-fiber laser can simultaneously emit two-color broadband LP
₁₁
transverse mode in the near-infrared region by sharing a common mode-selective coupler (MSC). The MSC mode converter is designed to achieve simultaneous dual-channel mode conversion corresponding to the wavelength regions at 1.0 and 1.5μm, in which each channel possesses broadband mode conversion from LP
₀₁
to LP
₁₁
mode with high mode purity. As a proof of concept, we implement an all-fiber ytterbium (Yb)- and erbium (Er)-doped fiber lasers with a mode-locked two-color LP
₁₁
modal output. The laser consists of two ring cavities combined with a common MSC mode converter. The generated LP
₁₁
modal pulses have a full width at half maximum of 11 and 8.1 nm for Yb- and Er-doped fiber laser, respectively. The presented fiber laser would represent a promising light source in the field of structured light and ultrafast optics.