Design of a single-mode fiber coupling system based on the modified Gerchberg-Saxton algorithm

Area of Science:

• Optics
• Optical Engineering
• Antenna Technology

Background:

• Cassegrain antennas suffer low coupling efficiency with hollow beams into single-mode fibers.
• Converting hollow beams to solid beams is a known method to enhance coupling efficiency.

Purpose of the Study:

• To design diffractive optical elements (DOEs) for converting hollow beams to solid beams.
• To improve the coupling efficiency of Cassegrain antenna systems.
• To analyze the adaptability of DOEs with varying focal length coupling lenses.

Main Methods:

• Designed shaping diffractive optical elements (DOEs) using a modified Gerchberg-Saxton algorithm (MGS) with Fresnel diffraction.
• Applied the MGS algorithm for circular symmetric beam shaping.
• Simulated and compared the performance of systems with and without shaping DOEs.

Main Results:

• Achieved a total transmission efficiency of 77.81% for the receiving antenna system at 1550 nm wavelength, accounting for system losses.
• Demonstrated that the DOEs shaping system shows better adaptability to different focal length coupling lenses.
• The variation in maximum coupling efficiency for the DOEs shaping system across different focal lengths was within 2.00%, a 6.73% improvement over lens shaping systems.

Conclusions:

• The developed DOEs effectively convert hollow beams to solid beams, significantly improving antenna coupling efficiency.
• The DOEs shaping system offers superior adaptability and stability with varying focal length coupling lenses.
• This research provides a reverse design approach for optical coupling systems, applicable to other optical designs.