III-V Semiconductor Optical Phase Shifter for Silicon Photonics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing silicon-based optical phase shifters in photonic integrated circuits suffer from inefficient phase shifting due to the weak plasma dispersion effect, leading to reduced variations in refractive index and increased optical losses.
Innovation Solution
The proposed optical device incorporates a phase shifter with an optical waveguide featuring a PN or PIN junction and a waveguide integrated capacitor, where a III-V semiconductor layer is heterogeneously integrated using a thin oxide bonding layer, allowing for dual control of charge carrier densities and enhanced phase shifting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma dispersion effect is used in silicon-based optical phase shifters, then phase shifting can be achieved, but the phase shifting efficiency is low due to weak effect strength
Solution Approach 1:
The patent employs a composite structure combining silicon waveguide with III-V semiconductor layer (such as InGaAsP) to enhance the plasma dispersion effect. The III-V layer has stronger electro-optic properties than pure silicon, creating a composite material system that achieves superior phase shifting efficiency while maintaining compatibility with standard silicon photonic platforms
Solution Approach 2:
The invention introduces a localized III-V semiconductor layer specifically at regions where optical mode confinement is strongest, typically at the waveguide core or cladding interfaces. This local enhancement strategy concentrates the electro-optic effect where it matters most for phase modulation, maximizing efficiency without requiring complete restructuring of the entire waveguide
2Reliability
If carrier depletion mode is used in PN junction, then phase shift is achieved, but optical losses increase
Solution Approach 1:
The patent optimizes multiple parameters including the thickness of the III-V layer, doping concentrations in both silicon and III-V regions, and junction geometry to achieve the desired phase shift with minimal carrier depletion. By carefully tuning these parameters, the design reduces the required carrier density change, thereby lowering optical absorption losses while maintaining effective phase control
Solution Approach 2:
The III-V semiconductor layer acts as an intermediary that enhances the electro-optic interaction between the applied electrical field and the optical mode. This intermediary layer amplifies the plasma dispersion effect, allowing for effective phase shifting with smaller carrier density changes, thus reducing the harmful optical losses associated with large carrier depletion
3Reliability
If carrier injection mode is used in PIN junction, then phase shift is achieved, but optical losses increase
Solution Approach 1:
The patent optimizes doping profiles, layer thicknesses, and junction dimensions to minimize the carrier injection requirement for achieving the desired phase shift. By reducing the necessary carrier injection level, the design minimizes free carrier absorption losses while maintaining adequate phase modulation depth
4Reliability
If MOSCAP structure is used, then phase shift is achieved through carrier accumulation, but optical losses increase
Solution Approach 1:
The invention replaces or supplements the conventional MOSCAP structure with a heterostructure involving III-V semiconductor layers that exhibit stronger electro-optic effects. This composite approach achieves the necessary carrier accumulation for phase shifting with reduced optical loss compared to standard silicon-based MOSCAP devices
Data Source
AI summary
Examples described herein relate to an optical device that entails phase shifting an optical signal. The optical device includes an optical waveguide having a first semiconductor material region and a second semiconductor material region formed adjacent to each other and defining a junction therebetween. Further, the optical device includes an insulating layer formed on top of the optical waveguide. Moreover, the optical device includes a III-V semiconductor layer formed on top of the insulating layer causing an optical mode of an optical signal passing through the optical waveguide to overlap with the first semiconductor material region, the second semiconductor material region, the insulating layer, and the III-V semiconductor layer thereby resulting in a phase shift in the optical signal passing through the optical waveguide.