Short and broadband silicon asymmetric Y-junction two-mode (de)multiplexer using fast quasiadiabatic dynamics

Abstract

A short and broadband silicon asymmetric Y-junction two-mode (de)multiplexer is proposed and simulated. An adiabaticity parameter suitable for high index-contrast silicon waveguides is defined. The fast quasiadiabatic dynamics protocol is used to homogeneously distribute adiabaticity over the device length. This protocol limits the power coupled into the unwanted waveguide eigenmode under a fixed value along the propagation. A 16 μm long mode (de)multiplexer with crosstalk < -34 dB is obtained. Simulations show that the optical bandwidth is as large as 300 nm (1400 nm ~ 1700 nm). The design is also fabrication tolerant.

Ultrashort and broadband silicon polarization splitter-rotator using fast quasiadiabatic dynamics

“…Previously, the FAQUAD strategy was applied to homogenize the adiabaticity in mode (de)multiplexing Y-junctions where the two modes have the same polarization [29,30]. From the analysis above, we have successfully verified that the FAQUAD strategy can be applied to the analysis of eigenmodes which goes through polarization conversion via mode hybridization, showing the versatility of the FAQUAD approach.…”

“…The result in Eq. 8improves the previous FAQUAD algorithm in [29,30], where the adiabaticity parameter and z are not completely decoupled in the analysis, leading to a less than optimal FAQUAD design. We use a commercial software (FIMMWAVE, Photon Design) [34] employing a finite difference method (FDM) to calculate the transverse component of the electric field E 2t and magnetic field H 3t associated with the second eigenmode (TM 0 to TE 1 ) and the third eigenmode (TE 1 to TM 0 ) of the taper, and the propagation constants β 2 of the second mode and β 3 of the third mode of the linear taper, and substitute E 2t , H 3t , β 2 and β 3 of the linear taper into Eq.…”

“…Asymmetric Y-junctions are often used to as mode sorters in photonic integrated circuits [29,30,35]. It has a two-modes stem waveguide and two single-mode output arms with different widths.…”

“…When the fundamental (second) mode of the stem propagates through the junction, it evolves into the fundamental mode of the wider (narrower) output arm, and vice versa. Previously, we have used the FAQUAD strategy to design an asymmetric Y-junction two-mode (de)multiplexer in silicon buried waveguide [30]. In this paper, we use the SOI strip waveguide structure, as shown in Fig.…”

“…By driving a single control parameter as close to the adiabatic limit as possible during the evolution, slow adiabatic evolution in the device can be significantly sped up. The FAQUAD approach has been applied to the design of Y-junction mode (de)multiplexers using the low index contrast polymer platform [29] as well as the high index contrast SOI platform [30]. However, the application of the FAQUAD protocol to polarization manipulation has yet to be investigated.…”