Enhanced Kerr nonlinearity in sub-wavelength diameter As(2)Se(3) chalcogenide fiber tapers

Area of Science:

• Nonlinear optics
• Materials science
• Optical fiber technology

Background:

• Chalcogenide glasses, such as As2Se3, exhibit high intrinsic nonlinear refractive index (n2).
• Sub-wavelength tapering of optical fibers offers a route to confine light to extremely small effective mode areas.

Purpose of the Study:

• To experimentally demonstrate and quantify enhanced nonlinear optical effects in highly nonlinear As2Se3 chalcogenide fibers with sub-wavelength waist diameters.
• To investigate the potential for ultra-low threshold supercontinuum generation using these tapered fibers.

Main Methods:

• Fabrication of As2Se3 chalcogenide fibers tapered to a sub-wavelength waist diameter (1.2 µm).
• Characterization of nonlinear effects using self-phase modulation (SPM) measurements.

Main Results:

• Demonstration of enhanced Kerr nonlinear effects in the tapered As2Se3 fibers.
• Inferred nonlinearity of 68 W⁻¹m⁻¹, which is 62,000 times greater than in standard silica single-mode fiber.
• Attribution of enhancement to a high n2 (500x silica) and small effective mode area (125x smaller than silica).

Conclusions:

• Highly nonlinear As2Se3 chalcogenide fibers tapered to sub-wavelength dimensions exhibit dramatically enhanced Kerr nonlinearity.
• These fibers present a promising platform for applications requiring strong nonlinear optical interactions, such as ultra-low threshold supercontinuum generation.