Planar Optical Waveguide Circuit Leaked Light Reflection

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Solution Overview

Problem

In planar optical waveguide circuits, leaked light propagating through undetermined routes interferes with output signals, reducing signal quality, especially when input optical signals are focused and combined in an input optical waveguide, and the propagation path of leaked light changes with variations in angle of incidence.

Innovation Solution

A planar optical waveguide circuit with a groove structure having reflective interfaces at +45 degrees and -45 degrees relative to the output optical waveguides, arranged alternately, to reflect leaked light and prevent interference with the output signal, along with a groove filled with a light-blocking material to attenuate light intensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a groove structure with a single reflective interface is used to separate leaked light, then the propagation path of leaked light can be separated from output light in determined paths, but it becomes ineffective when leaked light propagates through undetermined routes with varying angles of incidence

Engineering Contradiction:

Improveeffectiveness of leaked light separationVSAvoidhandling of undetermined propagation paths

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies asymmetry by using reflective interfaces at +45 degrees and -45 degrees relative to the output optical waveguide, arranged alternately. This asymmetric angular configuration ensures that leaked light regardless of its propagation direction (positive or negative angles) will be reflected away from the output path, making the solution effective for undetermined propagation routes.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent segments the single reflective interface into multiple alternating reflective interfaces at different angles (+45 degrees and -45 degrees). This segmentation creates multiple reflection opportunities for leaked light propagating at different angles, ensuring comprehensive coverage of undetermined propagation paths that a single interface cannot handle.

Inventive Principle:

Principle #1Segmentation

2Volume of moving object

If input light is focused with a focus lens and combined in an input optical waveguide to reduce module size, then the module size is reduced, but leaked light propagating through various routes interferes with the output signal

Engineering Contradiction:

Improvemodule sizeVSAvoidinterference from leaked light

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful leaked light into a beneficial reflected light path by using alternating reflective interfaces. The leaked light that would normally interfere with the output signal is instead reflected at +45/-45 degrees alternately, directing it away from the output optical waveguide and turning a harmful factor into a controlled reflection that no longer degrades signal quality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent addresses the leaked light interference problem by introducing angular dimensionality with reflective interfaces at +45 degrees and -45 degrees. This adds a dimensional approach to light path control, reflecting leaked light in angular directions away from the output path, thereby solving the interference issue while maintaining the compact focused lens configuration.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

The solution effectively reduces the interference of leaked light with the output signal by reflecting it away from the output path, improving signal quality and optical characteristics.

Implementation Method 1

a groove formed in the cladding layer, the groove having a reflective interface configured to reflect leaked light propagating in the cladding layer

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS11835761B2Planar optical waveguide circuit

Publication Date: 2023.12.05 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

The invention provides a planar optical waveguide circuit capable of preventing part of the input signal light that has not been combined in the waveguide and propagates as leaked light from interfering with the output signal. A planar optical waveguide circuit having an optical waveguide embedded in a cladding layer includes: a plurality of parallel output optical waveguides configured to emit light from a same end face; a groove having a reflective interface formed at an angle of +45 degrees relative to the output optical waveguides and configured to reflect leaked light propagating in the cladding layer; and a groove having a reflective interface formed at an angle of −45 degrees, the reflective interface formed at an angle of +45 degrees, the output optical waveguide, and the reflective interface formed at −45 degrees being arranged repeatedly in that order.