Compact silicon 10-mode multi/demultiplexer for hybrid mode- and polarisation-division multiplexing system

Abstract

To further increase the capacity of the optical transmission system, the hybrid mode- and polarisation-division multiplexing (MDM-PDM) technology has been proved to be an efficient approach by multiplexing dual polarisations for each orthogonal eigen mode. A hybrid (de)multiplexer [(De)MUX] is one of the most important fabrics for the hybrid MDM-PDM networks. A compact silicon 10-mode hybrid (De)MUX is proposed based on three cascaded asymmetric directional couplers (ADCs) based sections, three adiabatic tapers, and a polarisation beam splitter (PBS). The phase-matching conditions can be achieved by varying the widths of the bus waveguides for the TM modes and then by varying the widths of the access waveguides for the TE modes. The simulated results show that a compact total coupling length for TM1 ~ TM3 and TE1 ~ TE5 modes can be achieved to be 55.4 μm. In addition, the total loss of the proposed hybrid (De)MUX can be reduced benefitting from the fewer tapers compared with the conventional cascaded ADCs. The PBS is also optimised with a compact length of 7.0 μm and high extinction ratios of 32.9 dB and 15.4 dB for the TM0 and TE0 modes, respectively.

On-chip silicon photonic controllable 2 × 2 four-mode waveguide switch

“…The constructed structure can permit the switching operation of four WDM groups in the 2×2 configuration. Recently, adiabatic couplers are popularly used for multiplexing low-order modes into a multimode waveguide that such structures can carry up to dozens of optical modes in a multimode waveguide 9 , 59 , 60 .…”

“…Since each mode is an independent channel thus potentially makes a myriad of single channel capacity for optical communications systems and optical interconnects when it combines with the wavelength division multiplexing (WDM) technique 6 , 7 . Various kinds of MDM systems have been proposed, for example, mode demultiplexer 8 , 9 , mode converter 10 , 11 , waveguide crossing 12 , 13 , mode selective switch 14 , 15 , mode add-drop multiplexer 16 , 17 , and mode router 18 .…”

Topology design of digital metamaterials for ultra-compact integrated photonic devices based on mode manipulation

“…Besides reciprocal unidirectional transmission, mode division multiplexing (MDM) is another promising application of precise mode order manipulation, which enhances the transmission capacity of on-chip optical interconnection from an additional dimension to the wavelength. 19,21,32,39 Each mode inside the bus waveguide carries information individually, even at identical wavelength. Here, we focus on topologically designing a compact 1 Â 2 demultiplexer.…”

“…Manipulation of mode order in silicon waveguides has attracted extensive attention in terms of acting as promising building blocks in novel applications, such as on-chip all-optical diodes and mode division multiplexing systems. [1][2][3][4][5] Several conventional schemes have been proposed to achieve mode order conversion in waveguides, which include interferometer, [6][7][8] twodimensional photonic crystal structure, [9][10][11][12][13] metasurface, 14 deformed silicon waveguide, 15 partial etching, [16][17][18] direct waveguide coupling 5,19 and sub-wavelength grating coupling. 20,21 However, the footprints of the reported photonic devices based on the above mentioned schemes are mostly around 5 to 10 microns and even larger.…”

Mode hybridization analysis in thin film lithium niobate strip multimode waveguides

“…Hybrid modes are also reported to exhibit large group velocity dispersion compared to qTE and qTM modes, which could be useful in tunable time delays and optical signal processing applications 12 . While hybridization phenomenon is useful for mode converters and delays, the same could cause high-crosstalk in mode division multiplexing (MDM) applications 13 – 15 . Hybrid modes in SOI nanowires and LNOI are observed and reported in 4 , 9 .…”