Experimental demonstration of a two-mode (de)multiplexer based on a taper-etched directional coupler

Abstract

We experimentally demonstrate a compact, low-cross talk and fabrication-tolerant two-mode (de)multiplexer on the silicon-on-insulator platform. The device consists of a silicon wire waveguide coupled to a taper-etched waveguide. The partially etched taper structure is used to relax fabrication tolerance and thus to ensure high mode-conversion efficiency. The device is 68 μm in length, with a TE0-to-TE1 mode conversion loss of better than -0.8 dB demonstrated over the C-band wavelengths. In addition, the device demonstrates a low TE0-to-TE0 through waveguide insertion loss of better than -1.3 dB with modal cross talk lower than -26 dB, over a 65 nm wavelength range. Finally, we have experimentally demonstrated that the device is tolerant of fabrication errors of up to 20 nm. Better than -6 dB TE0-TE1 conversion loss with a cross talk lower than -23 dB over a 55 nm bandwidth has been obtained with a fabrication tolerance as large as 40 nm.

Silicon chip-scale space-division multiplexing: from devices to system

“…For ACs comprising two waveguides nearby, the geometry or refractive index of at least one waveguide is gradually varied along the propagation direction by tapering or partially etching [39,[45][46][47][48][49][50][51][52][53]. Although two supermodes are supported in the coupling region, only one can be excited.…”

Experimental realization of an O-band compact polarization splitter and rotator

“…Therefore, the control of fabrication dimensions is needed in order to achieve a low loss below 0.5 dB. However, we can also modify the structure for improving the fabrication tolerance, such as applying the tapered structures [16,19]. Fig.…”

WDM-compatible multimode optical switching system-on-chip

“…The coupling and conversion of the modes is easy to achieve by the precise fabrication capability of the waveguide structure with the advanced CMOS fabrication techniques, and the device performance is quite stable. A library of functional devices for multimode on-chip optical communications has been developed on a silicon photonics platform, including optical modulators [18][19][20][21][22][23], mode multiplexers and demultiplexers [24][25][26][27][28][29][30][31][32][33][34][35][36], multimode waveguide crossings [37], multimode waveguide bends [38], and multimode optical switches [39][40][41][42][43][44]. Moreover, germanium photodetectors are available for on-chip integration [45][46][47].…”