Super-resolving binary-source hypothesis testing with a double-clad fiber coupler

Area of Science:

• Optics and Photonics
• Astronomical Instrumentation

Background:

• Distinguishing between single and multiple point sources is crucial in various scientific fields, including astronomy.
• Traditional methods often face limitations due to the Rayleigh criterion, which defines the resolution limit for optical instruments.

Purpose of the Study:

• To develop and demonstrate a new technique for binary spatial mode demultiplexing.
• To utilize this technique for hypothesis testing of one or two point sources in an optical field.
• To assess the technique's capability in resolving sources below the classical diffraction limit.

Main Methods:

• Employing a double-clad fiber coupler as an optical mode sorter.
• Demultiplexing an incident optical field into fundamental and higher-order modes.
• Analyzing the ratio of multi-mode to single-mode power for source classification.

Main Results:

• Successfully demonstrated the capability to accurately identify two point sources separated below the Rayleigh limit.
• Achieved correct identification of two optical sources with relative brightness differences down to -20 dB.
• Showcased accurate detection of sources with separations 50x smaller than the Rayleigh limit for sources with <5 dB relative power difference.

Conclusions:

• The presented technique offers a simple and effective method for super-resolving classification of point emitters.
• This approach holds significant potential for applications in astronomical imaging, particularly for resolving binary systems.
• The technique provides a powerful tool for enhancing resolution beyond conventional limits.