Silicon Multimode Photonic Integrated Devices for on-Chip Mode-Division-Multiplexed Optical Interconnects

Abstract

Abstract-Multimode spatial-division multiplexing (SDM) technology has attracted much attention for its potential to enhance the capacity of an optical-interconnect link with a single wavelength carrier. For a mode-multiplexed optical-interconnect link, the functional elements are quite different from the conventional ones as multiple modes are involved. In this paper we give a review and discussion on multimode photonic integrated devices for mode-multiplexed opticalinterconnects. Light propagation and mode conversion in tapered waveguides as well as bent waveguides are discussed first. Recent progress on mode converter-(de)multiplexers is then reviewed. The demands of some functional devices used for mode-multiplexed opticalinterconnects are also discussed. In particular, the fabrication tolerance is analyzed in detail for our hybrid demultiplexer, which enables mode-/polarization-division-(de)multiplexing simultaneously.

Mode hybridization and conversion in silicon-on-insulator nanowires with angled sidewalls

“…6(d). This indicates this type of adiabatic taper is robust for the applications of polarization rotation (as demonstrated in [23][24][25][26]), which might be useful for on-chip polarization-handling systems as well as mode-division-multiplexed optical interconnect systems [39]. For this kind of applications, one can further strengthen this kind of mode hybridization and mode conversion by e.g.…”

“…For an SOI nanowires with angled sidewalls, mode conversion between the TM 0 mode and higher-order TE modes might happens due to the mode hybridization in the regions around some specific waveguide widths. This mode conversion efficiency is possible to be very high (even close to 100%) when the taper is long enough to be adiabatic, which might be useful for some applications of multimode photonics [39,43]. For example, the TM 0 → TE 1 mode conversion can be utilized to realize polarization splitter-rotators [23][24][25][26].…”

“…For example, the TM 0 → TE 1 mode conversion can be utilized to realize polarization splitter-rotators [23][24][25][26]. Such a kind of mode conversion also possibly enables the data-exchange between these two mode channels for a mode-divison-multiplex optical interconnect link [39]. On the other hand, the mode conversion will become harmful due to the possible excess loss as well as crosstalk.…”

10‐Channel Mode (de)multiplexer with Dual Polarizations

“…[12][13][14][15] Various silicon-based on-chip (de)multiplexers have been demonstrated in the past years, [6] including arrayed-waveguide gratings for WDM, [17] and onchip polarization-handling devices for PDM, [18] as well as mode (de)multiplexers for MDM. [19][20][21] In particular, mode (de)multiplexer for MDM have been proposed by utilizing multimode interferometers, [22] asymmetric Y-junctions, [23,24] topology structures, [25] adiabatic couplers, [26,27] and asymmetric directional couplers (ADCs), [28][29][30] etc. Among them, ADC-based mode (de)multiplexers are popular [30] because of the structural simplicity, the scalability, and the flexibility to excite a desired high-order mode from a launched fundamental mode.…”

On the Possibility of a Perfect Power Combiner

“…Therefore, we can make a power combiner of 100% efficiency if we let the two input fields have different wavelengths (i.e., the well-known wavelength-division-multiplexing technology, see, e.g., [4]), or have different polarizations (i.e., polarization multiplexing, see, e.g., [5]), or be of two modes orthogonal to each other (i.e., spatial mode multiplexing, see, e.g., [6]). Fig.…”