Transmission matrix of a multimode fiber: In-line vs off-axis holography

Area of Science:

• Optics and Photonics
• Wavefront Engineering
• Fiber Optics

Background:

• Multimode fibers (MMFs) offer potential for advanced imaging but present challenges due to complex light propagation.
• Accurate measurement of the MMF transmission matrix (TM) is crucial for precise wavefront control in MMF-based systems.

Purpose of the Study:

• To compare in-line and off-axis holography as phase retrieval methods for MMF TM measurement.
• To evaluate wavefront shaping quality for different target shapes using these holographic techniques.

Main Methods:

• Implemented a single optical setup to perform both in-line and off-axis holography.
• Measured the transmission matrix (TM) of a multimode fiber using both holographic techniques.
• Analyzed wavefront shaping performance for single-mode and complex free-form target projections.

Main Results:

• In-line holography demonstrated superior focus quality for single-mode target shapes.
• Off-axis holography proved more effective for projecting complex-shaped targets.
• A clear trade-off exists between the two holographic methods regarding wavefront shaping capabilities.

Conclusions:

• The choice between in-line and off-axis holography depends on the specific imaging application and target complexity.
• Findings guide the selection and optimization of holographic techniques for multimode fiber imaging.
• This research facilitates improved wavefront control in MMF-based optical systems.