Satellite-to-ground optical downlink model using mode mismatching multi-mode photonic lanterns.

Area of Science:

• Optical Communications
• Free-Space Optics (FSO)
• Photonics

Background:

• Free-space optical communications (FSOC) face significant atmospheric turbulence interference.
• Photonic lanterns (PLs) are crucial for mode diversity to mitigate turbulence.
• Satellite-to-ground links require robust solutions for reliable optical communication.

Purpose of the Study:

• To present and evaluate mode-mismatching multimode photonic lanterns (MM-PLs) for satellite-to-ground FSOC.
• To compare the performance of MM-PLs against mode-selective (MSPLs) and non-mode-selective (NSPLs) PLs.
• To analyze the impact of fiber position error (FPE) on coupling efficiency and SNR.

Main Methods:

• Evaluated coupling characteristics of MSPLs and NSPLs under varying turbulence intensities.
• Investigated the influence of fiber position error (FPE), including focal length deviation and lateral offset.
• Calculated and compared coupling power and signal-to-noise ratio (SNR) for few-mode PLs (FM-PLs) and MM-PLs.

Main Results:

• MSPLs outperform NSPLs under weak turbulence conditions.
• MM-PLs exhibit superior tolerance to fiber position errors (lateral offset > 12µm) compared to FM-PLs (3µm).
• MM-PLs show gentle SNR decrease (0.67-1.16 dB) at 12µm offset under weak turbulence, unlike FM-PLs (6.50-8.49 dB).

Conclusions:

• Mode-mismatching multimode photonic lanterns (MM-PLs) demonstrate significant advantages over few-mode photonic lanterns (FM-PLs).
• MM-PLs offer enhanced turbulence resistance and greater fiber position tolerance for satellite-to-ground FSOC.
• The findings highlight MM-PLs as a superior solution for reliable satellite-to-ground optical downlinks.