Mode multi/demultiplexing with parallel waveguide for mode division multiplexed transmission.

We propose a planar lightwave circuit (PLC)-based mode multi/demultiplexer (MUX/DEMUX) with an asymmetric parallel waveguide for mode division multiplexed (MDM) transmission. The PLCb-ased mode MUX/DEMUX has advantage of selectively exciting higher-order mode. We realize three-mode (LP(01), LP(11)a, and LP(21)a) multiplexing by using an asymmetric parallel waveguide. We then design and fabricate a PLC-based mode MUX/DEMUX on one chip by using our proposed LP(11) mode rotator to allow us to utilize the LP(11)b mode. We successfully multiplex the LP(01), LP(11)a, and LP(11)b modes and achieve a relatively low insertion loss over the C-band using our fabricated mode MUX/DEMUX. Our results indicate that the PLC-based mode MUX/DEMUX with a uniform height has the potential to increase the mode number by using an LP(11)b mode.

Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission.

We proposed a PLC-based mode multi/demultiplexer (MUX/DEMUX) with an asymmetric parallel waveguide for mode division multiplexed (MDM) transmission. The mode MUX/DEMUX including a mode conversion function with an asymmetric parallel waveguide can be realized by matching the effective indices of the LP(01) and LP(11) modes of two waveguides. We report the design of a mode MUX/DEMUX that can support C-band WDM-MDM transmission. The fabricated mode MUX/DEMUX realized a low insertion loss of less than 1.3 dB and high a mode extinction ratio that exceeded 15 dB. We used the fabricated mode MUX/DEMUX to achieve a successful 2 mode x 4 wavelength x 10 Gbps transmission over a 9 km two-mode fiber with a penalty of less than 1 dB.