All-fiber few-mode optical coherence tomography using a modally-specific photonic lantern.

Area of Science:

• Biomedical Optics
• Optical Engineering
• Medical Imaging

Background:

• Few-mode fiber (FM) Optical Coherence Tomography (OCT) has shown promise for enhanced contrast and resolution.
• Previous FM-OCT systems utilized sequential time-domain demultiplexing, limiting practical application.
• Robustness and efficiency are crucial for translating OCT technologies to clinical settings.

Purpose of the Study:

• To develop and present an all-fiber FM-OCT system employing a parallel modal demultiplexing scheme.
• To introduce a novel modally-specific photonic lantern (MSPL) for improved performance in FM-OCT.
• To establish a comprehensive coupling model for interpreting FM-OCT images and validate its predictions.

Main Methods:

• Development of a custom-built, wavelength-independent MSPL for OCT at 930 nm.
• Implementation of a parallel modal demultiplexing scheme within an all-fiber assembly.
• Validation using *in vitro* microbead phantoms and *ex vivo* biological samples.

Main Results:

• The MSPL achieved maximal fringe visibility for each fiber mode, ensuring robustness for clinical use.
• The developed coupling model accurately predicted FM-OCT image characteristics.
• The all-fiber FM-OCT system successfully demonstrated its capabilities on phantoms and biological tissues.

Conclusions:

• The novel all-fiber FM-OCT system with parallel modal demultiplexing and MSPL offers a robust platform for advanced biomedical imaging.
• The validated coupling model aids in the interpretation of complex FM-OCT data.
• This technology holds significant potential for improving diagnostic capabilities in clinical settings.