On-chip multiplexing conversion between wavelength division multiplexing–polarization division multiplexing and wavelength division multiplexing–mode division multiplexing

Abstract

A compact silicon-on-insulator device used for conversions between polarization division multiplexing (PDM) and mode division multiplexing (MDM) signals is proposed and experimentally demonstrated by utilizing a structure combining the improved two-dimensional grating coupler and two-mode multiplexer. The detailed design of the proposed device is presented and the results show the extinction ratio of 16 and 20 dB for X- and Y-pol input, respectively. The processing of 40 Gb/s signal is achieved within the C-band with good performance. The proposed converter is capable of handling multiple wavelengths in wavelength division multiplexing (WDM) networks, enabling the conversions between WDM-PDM and WDM-MDM, which is promising to further increase the throughput at the network interface.

Proposal for fabrication-tolerant SOI polarization splitter-rotator based on cascaded MMI couplers and an assisted bi-level taper

“…Figures 6(b)-6(c) show the mode propagation in this bi-level taper for different input modes and one can note that the mode conversion in the taper are achieved as we expected. [27,28], the width of our PS is broadened towards the outside of the central waveguide to reduce the undesired coupling and thus a lower crosstalk can be expected. One can note that a 0.5π phase difference can be achieved when dW = ~0.05 μm or 0.3 μm.…”

Multimode interference couplers as compact and robust static optical phase shifters

“…Recently, they have been used in novel optical 90°hybrids [1] and compact two-mode multi/demultiplexers [2]. For these devices, adiabatic tapers are typically used to slowly vary the width of an optical waveguide [1,3]. Tapering alters the propagation constant of the guided waveguide mode, causing its path length relative to an untapered waveguide of equal length to vary.…”

A fabrication-tolerant SOI polarization splitter-rotator with cascaded MMI couplers and an assisted bi-level taper

“…Figure 3(b) shows the phase difference between lights propagating through a straight waveguide and a phase shifter with the same length LPS = 10 μm. Compared with the PS in [7,8], the width of our PS is broaden towards outside of the waveguide to reduce the coupling with the central waveguide and thus a lower crosstalk can be obtained. One can note that a 0.5π phase difference can be achieved when dW = ~ 0.05 μm or 0.3 μm.…”