Optical Integrated Device Spot Size Converter Waveguide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of semiconductor optical amplifiers and phase modulators on the same substrate leads to increased connection loss and reflection due to differences in waveguide layer thicknesses, affecting the performance and tolerance of optical integrated devices.
Innovation Solution
The optical integrated device incorporates a passive waveguide region with a spot size conversion mechanism, featuring mesa structures and refractive index variations to optimize the thickness of waveguide layers, reducing connection loss and improving tolerance to peripheral optical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of waveguide layers is optimized for each element (phase modulator and semiconductor optical amplifier), then the performance of each element is improved, but the connection loss at the joint between elements is increased
Solution Approach 1:
A spot size converter is introduced as an intermediary waveguide structure between the phase modulator and semiconductor optical amplifier. This converter has a gradually changing cross-sectional area that adiabatically transforms the optical mode from the thick waveguide of the phase modulator to the thin waveguide of the semiconductor optical amplifier, enabling efficient coupling while allowing each element to maintain its optimal waveguide thickness
Solution Approach 2:
The waveguide structure transitions from a uniform thickness to a variable thickness structure in the spot size converter region. The cross-sectional area of the waveguide is gradually changed along the propagation direction, creating a continuous transformation of the optical mode that reduces reflection and coupling loss between elements with different thickness requirements
2Reliability
If the thickness of waveguide layers is optimized for each element, then element performance is improved, but reflection at the joint between elements becomes greater
Solution Approach 1:
The spot size converter acts as a transition region that mediates between the thick and thin waveguide sections. By gradually changing the waveguide dimensions, it prevents abrupt refractive index changes that cause reflection, allowing each element to maintain its optimal thickness while minimizing harmful reflections at the interface
Solution Approach 2:
The waveguide parameters (cross-sectional area, confinement factor) are continuously changed along the propagation direction in the spot size converter. This gradual parameter transformation creates an adiabatic transition that minimizes reflection by keeping the optical mode adapted to the local waveguide dimensions throughout the transition region
3Reliability
If waveguide layer thickness is optimized for each integrated element, then element-specific performance is improved, but tolerance to peripheral optical devices is reduced
Solution Approach 1:
The spot size converter serves as an interface mediator between the integrated elements and peripheral optical devices. It provides a transition region that can be optimized for coupling to external components while the internal elements maintain their optimal waveguide thicknesses, thereby preserving both element performance and external tolerance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables efficient spot size conversion and reduces connection loss, enhancing the performance and tolerance of optical integrated devices by optimizing waveguide layer thickness and refractive index differences.
Implementation Method 1
a quantum well layer arranged within a range of a mode field of light guided through the first core layer, the quantum well layer being configured to amplify light with electric current injected thereto
Implementation Method 2
The passive waveguide region includes a second spot size conversion region having, in addition to the first mesa structure, a second mesa structure having a first core portion, a lower cladding portion, and a second core portion
Data Source
AI summary
An optical integrated device includes a substrate a passive waveguide region and an active region. The active region and the passive waveguide region include a first mesa structure having an upper cladding portion formed of a same material as the upper cladding layer. The passive waveguide region includes a second spot size converter having the first mesa structure, a second mesa structure having a first core portion, a lower cladding portion, and a second core portion that are formed of same materials as the first core layer, the lower cladding layer, and the second core layer, respectively. The second mesa structure has a width wider than a width of the first mesa structure, and the width of the first mesa structure continuously changes along a longitudinal direction in which light is guided through the second core portion, the width being along a direction perpendicular to the longitudinal direction.