Analysis and characterization of Er-Yb codoped-depressed inner cladding fiber

Area of Science:

• Optical Fiber Technology
• Photonics
• Materials Science

Background:

• Traditional step-index fiber designs face limitations in balancing effective area and bending sensitivity.
• Developing advanced fiber structures is crucial for high-power and portable optical applications.

Purpose of the Study:

• To investigate a 125 μm-diameter erbium-ytterbium-codoped single-mode fiber with a depressed inner cladding.
• To optimize structural parameters for improved performance characteristics.
• To evaluate the fiber's suitability for high-power, compact optical devices.

Main Methods:

• Fabrication of a depressed inner cladding fiber.
• Systematic investigation of structural parameters (core radius, subsidence layer width) influencing cutoff wavelength, effective area, and macrobend loss.
• Characterization of single-mode properties, macrobend loss, and optical gain at 1550 nm and C-band.

Main Results:

• Achieved a macrobend loss of 0.06 dB/loop at a 10 mm bending radius.
• Maintained an effective area of 164.22 μm² with single-mode properties at 1550 nm.
• Obtained a maximum small signal gain of 40.9 dB with <1 dB gain fluctuation in the C-band.

Conclusions:

• The depressed inner cladding design effectively improves the trade-off between effective area and bending sensitivity.
• The developed fiber exhibits excellent performance, including low macrobend loss and high gain.
• The fiber is well-suited for high-power, small, portable, and handy optical fiber devices.