Infrared antenna measurement of the spatial coherence function

Area of Science:

• Optics and Photonics
• Electromagnetism
• Antenna Theory

Background:

• Partially coherent optical fields are fundamental in various optical phenomena.
• Measuring the degree of coherence is essential for characterizing optical wave propagation.
• Existing methods may face limitations in accuracy or applicability.

Purpose of the Study:

• To develop and validate a novel method for measuring the degree of coherence of partially coherent monochromatic optical fields.
• To utilize a dual-dipole phased-array antenna system coupled with a metal-oxide-metal tunnel diode detector for coherence measurements.
• To establish a calibration procedure for accurate coherence function extraction.

Main Methods:

• Employed a dual-dipole phased-array antenna system.
• Utilized a metal-oxide-metal tunnel diode detector for signal detection.
• Developed a calibration method to correct for propagation loss and device nonuniformity.
• Performed measurements at a wavelength of 10.6 µm.

Main Results:

• Successfully measured the degree of coherence for a partially coherent monochromatic optical field.
• Demonstrated that the degree of coherence correlates with electric field reception by antenna elements as a function of separation.
• Validated measurement results using electromagnetic simulations.
• Compared experimental findings with predictions from the Van Cittert-Zernike theorem.

Conclusions:

• The dual-dipole phased-array antenna system provides a viable method for measuring the degree of coherence.
• The developed calibration technique enhances measurement accuracy by mitigating system imperfections.
• The results align with established electromagnetic theories, confirming the method's validity.