Wavelength demultiplexer in multimode fiber that uses optimized holographic optical elements

Area of Science:

• Optics
• Photonics
• Fiber Optics

Background:

• Multimode fiber systems require efficient wavelength demultiplexing for signal processing.
• Existing demultiplexing technologies face challenges with broadband performance and crosstalk.

Purpose of the Study:

• To develop and demonstrate a single-transmission holographic optical element (HOE) demultiplexer.
• To achieve broadband five-channel demultiplexing in multimode fiber with high crosstalk isolation.

Main Methods:

• The demultiplexer integrates a dichromated gelatin hologram with a computer-generated hologram.
• A design utilizing nonspherical wavefronts, ray tracing, and optimization minimizes aberrations from wavelength shifts.
• The system was tested using a 780-nm laser diode source.

Main Results:

• The holographic optical element demultiplexer successfully achieved five-channel demultiplexing.
• High crosstalk isolation was maintained by reducing aberrations caused by recording-readout wavelength shifts.
• A channel separation of 300 µm (20 nm wavelength difference) was realized within the 0.8-0.88 µm operating range.

Conclusions:

• The developed holographic optical element demultiplexer is feasible for broadband five-channel applications in multimode fiber.
• This technology offers a promising solution for high-performance optical signal processing and communication.