Hybrid Optical Waveguide Structure for Low Loss and Precision

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Solution Overview

Problem

Conventional silica-based planar light circuits face challenges in reducing optical loss and increasing manufacturing complexity, particularly in forming compact optical devices with low power consumption and high precision, as they struggle to balance optical characteristics and dimension precision.

Innovation Solution

An optical device is designed with a structure that combines a channel-type and rib-type optical waveguide, featuring a core layer, slab layer, and rib layer with specific sectional area changes, optically coupled to minimize optical loss and facilitate easy manufacturing, using a silicon microfabrication technique on an SOI substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a channel-type optical waveguide is used to form bending optical waveguides with small radius of curvature, then optical loss is reduced, but manufacturing precision requirements increase significantly

Engineering Contradiction:
Improveoptical lossVSAvoiddimension precision
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The patent merges the channel-type optical waveguide and rib-type optical waveguide into a single integrated structure. The channel-type waveguide provides low optical loss for bending sections, while the rib-type waveguide offers manufacturing robustness. The two waveguide types are optically coupled through a coupling section where the channel-type waveguide transitions to the rib-type waveguide, allowing the system to simultaneously achieve low optical loss and reduced manufacturing precision requirements.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If a rib-type optical waveguide is used, then manufacturing precision requirements are reduced, but optical loss in bending waveguides increases

Engineering Contradiction:
Improvedimension precisionVSAvoidoptical loss
Core Design Contradiction:
Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent combines the advantages of both channel-type and rib-type waveguides by integrating them into a hybrid structure. The channel-type section is used specifically for bending waveguides where low optical loss is critical, while the rib-type section is used for straight waveguides where manufacturing ease is more important. The optical coupling between the two types ensures continuous light transmission with minimal loss.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If silica-based PLC is used for optical circuits, then manufacturing ease is maintained, but device dimension and power consumption increase

Engineering Contradiction:
Improvemanufacturing easeVSAvoiddevice dimension
Core Design Contradiction:
Ease of manufactureVSVolume of moving object

Solution Approach 1:

The patent changes the substrate material from conventional silica-based PLC to SOI (Silicon On Insulator) substrate, which enables the use of silicon microfabrication techniques. This parameter change allows for the formation of smaller, more compact optical devices with reduced dimensions while maintaining manufacturing feasibility through established silicon processing technologies. The high refractive index contrast of silicon enables tighter confinement of light, allowing for smaller device footprints.

Inventive Principle:
Principle #35Parameter changes

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 approach allows for the formation of optical devices with reduced optical loss and improved manufacturing ease, enabling the creation of compact, low-power optical circuits with enhanced precision and performance.

Implementation Method 1

the core layer (13) and both of the slab layer (14) and the rib layer (15) are optically coupled

Methodology Applied
Scientific EffectOptical coupling: Waveguide (optics)

Data Source

PatentEP2634613B1Optical device, optical transmitter, optical receiver, optical transceiver, and method of manufacturing optical device
Publication Date: 2017.12.06 FUJITSU LTD
  • EP2634613B1 patent drawingFigure 1
  • EP2634613B1 patent drawingFigure 2
  • EP2634613B1 patent drawingFigure 3

AI summary

An optical device includes: a first cladding layer (12); a core layer (13) disposed on the first cladding layer (12) and, with increase in its sectional area, extending from a first end which receives/outputs light along a direction from the first end toward a second end; a slab layer (14) disposed on the first cladding layer (12) and extending to the second end along the direction from the first end toward the second end; a rib layer (15) disposed on the slab layer (14) and, with decrease in its sectional area, extending to the second end along the direction from the first end toward the second end; and a second cladding layer disposed on the core layer (13)and the rib layer (15). The core layer (13) and both of the slab and rib layers (14, 15) are optically coupled in a part in which the sectional are of the core and rib layers (14, 15) is the maximum.