Endlessly single-mode photonic crystal fiber as a high resolution probe

Area of Science:

• Optics and Photonics
• Fiber Optics
• Interferometry

Background:

• Characterizing optical fields, especially diffraction-limited spots, is crucial for microscopy and spectroscopy.
• Existing methods for analyzing optical field details can be complex and expensive.
• Endlessly single-mode (ESM) photonic crystal fibers offer unique light-guiding properties.

Purpose of the Study:

• To develop a novel, cost-effective method for high-resolution characterization of optical fields.
• To demonstrate super-resolution imaging capabilities using ESM fibers and interferometry.
• To explore the guidance of high numerical aperture (NA) light fields within ESM fiber structures.

Main Methods:

• Utilizing ultra-broadband light focused onto a diffraction-limited spot.
• Employing an endlessly single-mode (ESM) photonic crystal fiber for light sampling.
• Detecting both field amplitude and phase with a SEA TADPOLE interferometer.

Main Results:

• Achieved spatial resolution up to 2.5 times finer than the fiber mode size.
• Resolved periodic features within the bipolar oscillating field in the transverse section.
• Demonstrated guidance of a high-NA light field within the fine structure of an ESM fiber mode.

Conclusions:

• The developed technique provides an inexpensive method for characterizing the point-spread function of optical fields.
• The super-resolution enhancement is applicable to intensity measurements in various single-mode fibers.
• Results are particularly valuable for fiber-based devices like interferometers, spectrometers, and sensors where fiber tips define spatial resolution.