Suspended-core fiber with embedded GaSe nanosheets for second harmonic generation

We report an all-fiber scheme for the second harmonic generation (SHG) by embedding gallium selenide (GaSe) nanosheets into a suspended-core fiber (SCF). Based on modes analysis and theoretical calculations, the phase-matching modes from multiple optional modes in the SHG process and the optimal SCF length are determined by calculating the effective refractive index and balancing the SHG growth and transmission loss. Due to the long-distance interaction between pumped fundamental mode and GaSe nanosheets around the suspended core, an SHG signal is observed under a milliwatt-level pump light, and exhibits a quadratic growth with the increased pump power. The SHG process is also realized in a broad wavelength range by varying the pump in the range of 1420 similar to 1700 nm. The SCF with the large air cladding and suspended core as an excellent platform can therefore be employed to integrate low-dimensional nonlinear materials, which holds great promise for the applications of all-fiber structures in new light source generating, signal processing and fiber sensing. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

We present an all-fiber scheme for second harmonic generation (SHG) by incorporating gallium selenide (GaSe) nanosheets into a suspended-core fiber (SCF). The phase-matching modes and optimal SCF length are determined through mode analysis and theoretical calculations. The SHG signal, observed under milliwatt-level pump light, exhibits a quadratic growth with increasing pump power due to the long-distance interaction between the pumped fundamental mode and GaSe nanosheets. Additionally, the SHG process is achieved over a broad wavelength range by varying the pump wavelength.