InP optical amplifiers with Euler U-bend waveguide geometry for low-loss flip-chip hybrid integration

TL;DR

This paper presents the development of low-loss InP optical amplifiers with Euler U-bend waveguides, enhancing hybrid integration on silicon photonics by reducing coupling losses and simplifying chip alignment.

Contribution

It introduces a novel U-bend waveguide geometry for InP amplifiers, demonstrating low loss performance and integration advantages on silicon photonics platforms.

Findings

Achieved 0.56 dB loss in a 50 μm bend radius U-bend waveguide.

Analyzed interface effects between bends and straight waveguides.

Demonstrated successful integration on silicon-on-insulator platform.

Abstract

We report on the development of InP-based semiconductor amplifiers with a U-bend waveguide geometry having the input and output ports on one facet only. This waveguide geometry simplifies the chip alignment during the hybrid integration on silicon photonics platforms ultimately reducing the coupling losses, improving the integration yield, and minimizing the length of the optoelectronic chip. To achieve low loss U-bends with small footprint, we utilize the Euler bend geometry previously demonstrated on silicon and GaAs platforms. We analyze the gain properties of the devices by operating them as laser diodes at room temperature. Low loss U-bend performance with a 0.56 dB for a 50 $\mu$m effective bending radius bend in a single-mode strip InP waveguide is demonstrated. The interface between bend and straight waveguides was studied by comparing deep etched waveguides to a combination of shallow straight waveguides and deep etched bends. The effects of this interface on the device losses, electric properties and spectrum are reported. The implications related to having a bend section on the carrier injection and gain are discussed. Finally, results on the integration trials on silicon-on-insulator platform are presented.