Fiber-to-Chip Optical Coupler with Curved Mirrors and Spacer

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Solution Overview

Problem

Current methods for coupling optical fibers to photonic integrated circuits (PICs) face challenges such as poor assembly tolerance, signal losses, and complex alignment requirements, making mass production of PICs and optical couplers inefficient and costly.

Innovation Solution

An adaptive optical coupling solution using a spacer with first and second curved mirrors and a tilted flat mirror, allowing for high tolerance alignment and passive positioning of optical fibers relative to PICs, enabling efficient and scalable fiber-to-chip and chip-to-fiber connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional butt connection or angled tip techniques are used to couple optical fibers to PICs, then coupling efficiency can be achieved, but assembly tolerance becomes very tight and alignment precision requirements become extremely high

Engineering Contradiction:
Improvecoupling efficiencyVSAvoidalignment tolerance
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces a fiber optic connector as an intermediary component between the optical fiber and the PIC. This connector includes a groove structure that passively positions and aligns the optical fiber with the PIC, eliminating the need for complex active alignment mechanisms. The intermediary connector absorbs the alignment tolerance requirements, allowing for much looser assembly specifications while maintaining high coupling efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The connector groove is pre-formed with specific geometric dimensions and orientation that automatically guide the optical fiber into the correct alignment position with the PIC. This preliminary structural preparation ensures that when the fiber is inserted into the groove, it is passively aligned to the waveguide coupling point without requiring post-assembly adjustment or expensive active positioning equipment.

Inventive Principle:
Principle #10Preliminary action

2Loss of energy

If precise active positioning and alignment techniques are used to achieve efficient fiber-to-PIC connectivity, then signal loss is reduced, but manufacturing cost increases and mass production becomes infeasible

Engineering Contradiction:
Improvesignal lossVSAvoidmanufacturing cost
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The connector groove structure is designed to self-align the optical fiber with the PIC through its geometric constraints. The groove dimensions and shape automatically position the fiber at the correct location and orientation, allowing the assembly to self-correct alignment errors without requiring external positioning equipment or manual adjustment. This self-aligning mechanism dramatically reduces manufacturing complexity and enables cost-effective mass production while maintaining low signal loss.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The fiber optic connector acts as a mediator that translates the loose tolerance requirements of mass production into precise alignment at the fiber-PIC interface. The connector's pre-formed groove structure absorbs the alignment tolerance, allowing inexpensive manufacturing processes to produce components that achieve high coupling efficiency when assembled together.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If complex alignment equipment and labor intensive assembly solutions are used, then alignment precision is improved, but productivity decreases and mass production is not feasible

Engineering Contradiction:
Improvealignment precisionVSAvoidmass production capability
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The connector groove is pre-manufactured with precise geometric dimensions that encode the alignment information. This preliminary structuring of the alignment function into the connector's physical form allows for rapid assembly without requiring complex measurement or positioning equipment during the assembly process, thereby enabling high-volume production while maintaining alignment precision.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The self-aligning groove structure eliminates the need for expensive active positioning equipment and labor-intensive manual alignment procedures. The geometric constraints of the groove automatically guide the fiber into the correct position, allowing unskilled workers or automated assembly machines to achieve precise alignment quickly and consistently, thereby dramatically increasing productivity and enabling mass production.

Inventive Principle:
Principle #25Self-service

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 solution provides high signal efficiency with relaxed alignment tolerances, enabling compact and secure packaging of PICs and facilitating mass production by reducing the need for precise and expensive alignment techniques.

Implementation Method 1

a first curved mirror (140), a second curved mirror (150), and a tilted flat mirror (160) arranged to reflect and redirect an optical signal from the optical fiber (120) to the PIC (110)

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a first curved mirror (140), a second curved mirror (150)

Methodology Applied
Scientific EffectFocusing: Focusing

Implementation Method 3

arranged to reflect and redirect an optical signal from the optical fiber (120) to the PIC (110)

Methodology Applied
Scientific EffectCollimation:

Data Source

PatentEP3347751B1A fiber to chip optical coupler and method of manufacturing thereof
Publication Date: 2021.09.01 TERAMOUNT LTD
  • EP3347751B1 patent drawingFigure 1
  • EP3347751B1 patent drawingFigure 2
  • EP3347751B1 patent drawingFigure 3A

AI summary

An optical coupler for coupling an optical fiber to a photonic integrated circuit (PIC) is presented. The optical coupler comprises a first curved mirror included in a first substrate layer of the PIC and at a first predefined lateral distance from an optical transceiver associated with the PIC; a second curved mirror included in a second substrate layer and placed at a second predefined lateral distance from the optical fiber; and a spacer located between the first substrate layer and the second substrate layer.