Measuring the complex frequency response of multimode optical fibers.

Area of Science:

• Optical Engineering
• Fiber Optics Communications
• Metrology

Background:

• Measuring the complex frequency response (transfer function) of multimode optical fibers is crucial for understanding signal propagation.
• Accurate phase angle measurement of the transfer function (H(omega)) in multimode fibers presents significant technical challenges.
• Existing methods often lack the precision required for detailed optical fiber characterization.

Purpose of the Study:

• To introduce an improved frequency-sweeping method for measuring the complex frequency response of multimode optical fibers.
• To address the difficulties in accurately measuring the phase angle of H(omega).
• To provide a more reliable technique for optical fiber analysis.

Main Methods:

• A novel frequency-sweeping technique is proposed.
• A single-mode optical fiber is utilized as a reference for phase angle measurements.
• The method focuses on overcoming the inherent difficulties in phase angle determination for H(omega).

Main Results:

• The proposed method successfully measures the complex frequency response, including the phase angle, of multimode optical fibers.
• Measurements were performed on two distinct multimode fibers.
• Results obtained using the new technique were compared with those from a conventional pulse method.

Conclusions:

• The developed frequency-sweeping method offers an improved approach to measuring multimode optical fiber transfer functions.
• The use of a single-mode fiber reference effectively resolves phase angle measurement inaccuracies.
• This technique enhances the accuracy and feasibility of characterizing multimode optical fiber properties.