Scalable Hermite-Gaussian mode-demultiplexing hybrids

Area of Science:

• Optics and Photonics
• Optical Communications
• Integrated Optics

Background:

• Mode-division multiplexing (MDM) is a promising technique for increasing optical fiber communication capacity.
• Coherent detection of MDM signals requires complex optical components for demultiplexing and signal processing.
• Existing methods for mode demultiplexing often suffer from high insertion loss and fabrication complexity.

Purpose of the Study:

• To propose and demonstrate a novel Hermite-Gaussian (HG) mode-demultiplexing hybrid (MDH) for coherent detection of MDM signals.
• To simplify the construction of MDH devices by reducing the number of required phase masks.
• To achieve low insertion loss and mode-dependent loss in the MDH device.

Main Methods:

• The MDH is realized using the multi-plane light conversion technique.
• An isosceles right triangle output layout is employed to minimize the number of phase masks.
• Numerical simulations are used to demonstrate a 10-HG mode MDH with five phase masks.

Main Results:

• A 10-HG mode MDH was simulated, achieving an insertion loss (IL) as low as -2.3 dB and mode-dependent loss (MDL) of 1.7 dB.
• Optimization of MDH parameters, including input/output beam waists, further reduced the IL to -1.5 dB.
• The proposed device integrates demultiplexing, local oscillator splitting, and optical 90-degree mixing functionalities.

Conclusions:

• The developed HG-MDH offers a simplified and efficient solution for coherent detection of MDM signals.
• The device's compact design and low loss characteristics make it suitable for next-generation optical communication systems.
• Further optimization can lead to even lower losses, enhancing the performance of MDM systems.