Mode Demultiplexing Hybrid Simplifies Coherent Optical Front End

Technology #34398

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Guifang Li, Ph.D.
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He Wen, Ph.D.
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Patent Protection

US Patent Pending
Mode demultiplexing hybrids for mode-division multiplexing coherent receivers
Photonics Research, Vol. 7, Issue 8, pp. 917-925 (2019).


  • Multi-functional device reduces the size and power consumption of space-division multiplexing (SDM) receivers
  • Can simultaneously perform mode demultiplexing, local oscillator power splitting, and optical 90-degree phase deconstruction using multi-plane light conversion (MPLC)


Researchers at the University of Central Florida have designed a single device that integrates mode demultiplexing, local oscillator power splitting, and optical 90-degree phase deconstruction using a multi-plane light converter (MPLC). As a result, the invention enables more reliable and robust coherent optical signals for communications systems.

Today’s current optical front ends use hybrids that require a large footprint and complicated receiver structures. In contrast, the UCF Mode-Demultiplexing Hybrid (MDH) can reduce the number of devices needed in a space-division multiplexing (SDM) coherent receiver while reducing power consumption. Besides simplifying current coherent optical front ends for mode-division multiplexing (MDM) receivers, the MDH can also improve multicore fiber systems, where the mode demultiplexer is replaced by a fan-out device.

Technical Details

The invention comprises an MDH apparatus and methods for designing the MDH. In one example, the apparatus can consist of an entrance plane adapted to receive inputs, including a signal with a specified phase/amplitude profile and a reference. The signal and reference inputs are spatially separated, occupy non-overlapped areas, and can coherently interfere. The MDH contains a reflective cavity MPLC with input optically coupled to the signal and reference inputs. Lastly, an exit plane is optically coupled to an output of the MPLC, which has spatially overlapping signal and reference spots. Each spot has a different respective phase shift imposed by the MPLC so that all the output spots are mutually orthogonal. Thus, a single MDH enables mode demultiplexing and optical 90-degree mixing of the inputs. In numerical simulations, the research team demonstrated the use of a three-mode MDH using four phase plates—one more than required by an MPLC mode demultiplexer. The performance is comparable to that of commercial single-mode 90-degree hybrids.

Partnering Opportunity

The research team is looking for partners to develop the technology further for commercialization.


  • Simplifies the structure of the coherent optical front end
  • Improves system performance and reduces costs
  • Operates across multiple wavelength-MDM channels
  • Eliminates the need for phase stabilization, resulting in power savings

Market Application

  • Optical communication systems
  • Mode-division multiplexed optical transmission