Optical memory effect in square multimode fibers.

Area of Science:

• Optics and Photonics
• Waveguide Technology
• Materials Science

Background:

• Optical memory effects are crucial for information processing and storage.
• Multimode fibers typically exhibit complex light scattering, making predictable light manipulation challenging.
• Square-core fibers offer unique symmetry properties not found in circular-core fibers.

Purpose of the Study:

• To experimentally demonstrate and theoretically model the translational optical memory effect in square-core multimode fibers.
• To investigate the influence of waveguide symmetry on light propagation and output patterns.
• To quantify the shift distances and fiber lengths over which the effect is observable.

Main Methods:

• Experimental setup using 532-nm coherent light source.
• Utilizing a square-core step-index multimode fiber.
• Analyzing output speckle pattern shifts in response to input beam displacements.
• Developing a theoretical model based on a perfectly reflective square waveguide.

Main Results:

• Observed a translational optical memory effect where input shifts result in output shifts along four directions.
• The symmetry of the square core is identified as the cause of this directional shifting.
• The effect was demonstrated for input shift distances up to 10 µm.
• The phenomenon persisted after propagation through several centimeters of fiber.

Conclusions:

• Square-core multimode fibers exhibit a unique translational optical memory effect.
• The observed effect is governed by the waveguide's symmetry properties.
• This finding opens possibilities for novel optical manipulation and sensing applications in square-core fiber systems.