Three-dimensional Ag₂S cubes for switchable multi-wavelength ultrashort pulse application.

Area of Science:

• Materials Science
• Optoelectronics
• Laser Physics

Background:

• Three-dimensional (3D) materials possess excellent nonlinear optical properties crucial for optoelectronics and ultrafast fiber lasers.
• Silver sulfide (Ag2S), a 3D material with a cubic structure and high absorption, is investigated for its potential in laser applications.

Purpose of the Study:

• To characterize the nonlinear optical properties of Ag2S.
• To demonstrate the use of Ag2S as a saturable absorber (SA) in a fiber laser.
• To achieve and analyze dual-wavelength mode locking and wavelength tunability.

Main Methods:

• A double-balance detection system was employed to measure the saturation absorption intensity and modulation depth of Ag2S.
• Ag2S was integrated as a saturable absorber into a ring fiber laser cavity.
• Polarization controllers were used to tune the laser output from dual-wavelength to multiple wavelengths.

Main Results:

• The saturation absorption intensity of Ag2S was measured at 226.6 MW cm⁻² with a modulation depth of 13.9%.
• Stable dual-wavelength mode locking was achieved at 1536.9 nm and 1544.5 nm with 3 dB bandwidths of 1.3 nm and 1.5 nm, respectively.
• A tunable range of 13.1 nm was realized by adjusting the polarization controller, transitioning from dual- to multi-wavelength operation.

Conclusions:

• This study reports the first multiplexed fiber laser utilizing Ag2S as a saturable absorber.
• The results highlight Ag2S as a promising material for developing multifunctional compact fiber lasers.
• The demonstrated system offers potential applications in fiber sensing, telecommunications, and optical communication.