Mode control in a multimode fiber through acquiring its transmission matrix from a reference-less optical system.

Area of Science:

• Optics and Photonics
• Computational Imaging
• Optimization Algorithms

Background:

• Multimode fibers (MMFs) are crucial for high-capacity communication but suffer from modal dispersion.
• Characterizing the transmission matrix (TM) of MMFs is essential for controlling light propagation.
• Existing methods often require complex setups and interferometric measurements.

Purpose of the Study:

• To develop a simplified method for acquiring the transmission matrix (TM) of a multimode fiber.
• To enable precise control of light modes within optical fibers.
• To overcome limitations of existing TM characterization techniques.

Main Methods:

• A simple imaging system combined with semidefinite programming (a convex optimization algorithm).
• Utilizing a phase-only spatial light modulator to shape input light modes.
• Acquiring the TM using only intensity measurements, without reference arms or interferometry.

Main Results:

• Successfully generated the transmission matrix (TM) of a multimode fiber using intensity-only measurements.
• Demonstrated the ability to induce strong mode interference at the fiber output by modulating input signal phase.
• Validated a non-interferometric, reference-free approach for TM characterization.

Conclusions:

• The developed method offers a simple and powerful way to characterize multimode fiber transmission matrices.
• This technique can compensate for modal dispersion in fiber optic communication systems.
• Potential applications include next-generation biomedical imaging, quantum communication, and cryptography.