Low-crosstalk orbital angular momentum fiber coupler design.

Area of Science:

• Optoelectronics
• Photonics
• Fiber optics

Background:

• Orbital angular momentum (OAM) multiplexing offers enhanced data capacity in fiber optic communications.
• Efficient and low-crosstalk beam splitters are crucial for implementing OAM-based systems.

Purpose of the Study:

• To propose and analyze a novel fiber coupler for splitting OAM modes.
• To achieve low crosstalk and high mode purity in the OAM beam splitter.
• To demonstrate tunable coupling over the C-band for practical OAM fiber systems.

Main Methods:

• Design of a fiber coupler using two separate, parallel microfibers.
• Optimization of microfiber center-to-center distance to minimize crosstalk.
• Utilizing a thermosensitive liquid to tune the operating wavelength across the C-band.

Main Results:

• Achieved crosstalk below -20 dB, ensuring OAM mode purity greater than 99%.
• Demonstrated high coupling efficiency (>97%) within the 1545-1560 nm range.
• Successfully tuned the coupler's operating wavelength across the entire C-band.

Conclusions:

• The proposed microfiber coupler is a promising component for low-crosstalk OAM mode splitting.
• Tunable coupling across the C-band enhances its applicability in future OAM fiber communication systems.
• This design facilitates the development of more robust and efficient OAM fiber networks.