Abstract

Compact and low-loss waveguide bends are vital for enhancing the integration density of on-chip photonic devices. The bend loss becomes extremely critical, particularly for compact bends in low-index-contrast platforms such as Indium Phosphide (InP). To address this issue, we introduce an elliptical width-modulated bend, which exhibits low loss. For example, at 6 µm radius bend loss for elliptical width-modulated bend is 0.22 dB per 90°, resulting in 40% and 27% reduction compared to conventional circular bends and circular width-modulated bends, respectively with only a 15% increase in footprint providing a better loss–area trade-off. Additionally, conventional effective-index-based analytical models do not account for the impact of width modulation. In this work, we develop an enhanced analytical bend-loss formulation that incorporates these effects and validates its accuracy through close agreement with full three-dimensional Finite-Difference Time-Domain (3D-FDTD) simulations.

Abstract

Compact and low-loss waveguide bends are vital for enhancing the integration density of on-chip photonic devices. The bend loss becomes extremely critical, particularly for compact bends in low-index-contrast platforms such as Indium Phosphide (InP). To address this issue, we introduce an elliptical width-modulated bend, which exhibits low loss. For example, at 6 µm radius bend loss for elliptical width-modulated bend is 0.22 dB per 90°, resulting in 40% and 27% reduction compared to conventional circular bends and circular width-modulated bends, respectively with only a 15% increase in footprint providing a better loss–area trade-off. Additionally, conventional effective-index-based analytical models do not account for the impact of width modulation. In this work, we develop an enhanced analytical bend-loss formulation that incorporates these effects and validates its accuracy through close agreement with full three-dimensional Finite-Difference Time-Domain (3D-FDTD) simulations.

Abstract

Compact and low-loss waveguide bends are vital for enhancing the integration density of on-chip photonic devices. The bend loss becomes extremely critical, particularly for compact bends in low-index-contrast platforms such as Indium Phosphide (InP). To address this issue, we introduce an elliptical width-modulated bend, which exhibits low loss. For example, at 6 µm radius bend loss for elliptical width-modulated bend is 0.22 dB per 90°, resulting in 40% and 27% reduction compared to conventional circular bends and circular width-modulated bends, respectively with only a 15% increase in footprint providing a better loss–area trade-off. Additionally, conventional effective-index-based analytical models do not account for the impact of width modulation. In this work, we develop an enhanced analytical bend-loss formulation that incorporates these effects and validates its accuracy through close agreement with full three-dimensional Finite-Difference Time-Domain (3D-FDTD) simulations.

Abstract

Compact and low-loss waveguide bends are vital for enhancing the integration density of on-chip photonic devices. The bend loss becomes extremely critical, particularly for compact bends in low-index-contrast platforms such as Indium Phosphide (InP). To address this issue, we introduce an elliptical width-modulated bend, which exhibits low loss. For example, at 6 µm radius bend loss for elliptical width-modulated bend is 0.22 dB per 90°, resulting in 40% and 27% reduction compared to conventional circular bends and circular width-modulated bends, respectively with only a 15% increase in footprint providing a better loss–area trade-off. Additionally, conventional effective-index-based analytical models do not account for the impact of width modulation. In this work, we develop an enhanced analytical bend-loss formulation that incorporates these effects and validates its accuracy through close agreement with full three-dimensional Finite-Difference Time-Domain (3D-FDTD) simulations.