Orbital angular momentum mode groups multiplexing transmission over 2.6-km conventional multi-mode fiber

Area of Science:

• Optics and Photonics
• Optical Communications

Background:

• Twisted light with orbital angular momentum (OAM) features helical phase fronts and doughnut intensity profiles.
• OAM light has applications in microscopy, metrology, and quantum optics, with emerging use in optical communications.
• Current OAM communication systems often rely on specialty fibers, limiting widespread adoption.

Purpose of the Study:

• To investigate the feasibility of using conventional graded-index multi-mode fibers (MMF) for OAM-based optical communications.
• To demonstrate data transmission using multiple OAM mode groups over a standard MMF.

Main Methods:

• Utilized fiber-compatible mode exciting and filtering elements to generate the first four OAM mode groups within an MMF.
• Conducted a 2.6-km transmission experiment transmitting four data-carrying OAM mode groups (OAM_0,1, OAM_+1,1/OAM_-1,1, OAM_+2,1, OAM_+3,1).
• Performed multiplexing transmission of two data-carrying OAM mode groups over the 2.6-km MMF.

Main Results:

• Successfully transmitted data using four OAM mode groups over a 2.6-km conventional MMF.
• Demonstrated multiplexing of two OAM mode groups with low crosstalk.
• Achieved this multiplexing transmission without the need for multiple-input multiple-output digital signal processing (MIMO-DSP).

Conclusions:

• Conventional MMFs can be directly utilized for OAM optical communications.
• The proposed method offers a cost-effective and practical approach for OAM communication systems.
• This research opens new avenues for fiber-based OAM applications using existing fiber infrastructure.