Wavelength-Selectable Laser Using Diffraction Grating

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Solution Overview

Problem

Current WDM-PON systems face inefficiencies in bandwidth utilization and maintenance due to the need for multiple fibers and the high cost and complexity of continuously tunable lasers, which are sensitive to external conditions and require precise alignment.

Innovation Solution

A wavelength-selectable laser device using a dispersive optical element, such as a diffraction grating, to spatially select wavelengths by directing different wavelengths to specific locations on a reflector, allowing for selection without continuous tuning, and employing a mirror array or spatial filter for stable and cost-effective operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If continuously tunable lasers are used to provide wavelength selection, then wavelength tunability is achieved, but device complexity and cost increase due to sensitivity to external conditions and requirement for external locking mechanisms

Engineering Contradiction:

Improvewavelength tunabilityVSAvoidcomplexity of external locking mechanisms

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the wavelength selection function from a continuously tunable laser and implements it using a fixed-wavelength laser combined with a tunable filter. This separates the wavelength generation (fixed laser) from the wavelength selection (tunable filter), eliminating the need for complex external locking mechanisms while maintaining wavelength tunability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a tunable filter as an intermediary component between the fixed-wavelength laser and the optical output. This mediator enables wavelength selection without requiring the laser itself to be continuously tunable, thereby reducing device complexity and eliminating the need for external locking mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If multiple fibers are deployed to connect multiple users, then network capacity increases, but deployment and management expense increases

Engineering Contradiction:

Improvenetwork capacityVSAvoiddeployment expense

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent merges multiple wavelength channels onto a single optical fiber using wavelength division multiplexing. By enabling a single laser device to operate at multiple wavelengths, the system can carry multiple data streams simultaneously over one fiber, replacing the need for multiple separate fibers and reducing deployment costs.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a universal laser device that can function at multiple wavelengths through wavelength selection. This multi-functional device can serve multiple network roles and connect to multiple users via wavelength multiplexing, eliminating the need for dedicated fibers for each user and reducing overall network deployment expense.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If TDM approach is used to share fiber among transmitters, then fiber count is reduced, but bandwidth utilization efficiency decreases

Engineering Contradiction:

Improvefiber countVSAvoidbandwidth utilization efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent contrasts TDM's periodic time-slot-based transmission with WDM's simultaneous wavelength-based transmission. While TDM uses periodic time slots that leave gaps for stabilization, the wavelength-selectable laser enables continuous transmission on multiple wavelengths simultaneously, eliminating the periodic interruptions and improving bandwidth utilization efficiency.

Inventive Principle:

Principle #19Periodic action

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

Enables efficient bandwidth utilization and simplified maintenance by allowing a single device to be used across different locations, reducing the need for precise alignment and external locking mechanisms, while maintaining stability over time.

Implementation Method 1

a dispersive optical element for spatially separating different wavelengths of the light such that different wavelengths are directed from the dispersive optical element at different angles

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

a back reflector for reflecting at least one selected wavelength of the wavelengths of light back to the laser emitter

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS10418782B2Wavelength-selectable laser device providing spatially-selectable wavelenth(s)

Publication Date: 2019.09.17 APPLIED OPTOELECTRONICS INC(US)

AI summary

A wavelength-selectable laser device providing spatially-selectable wavelength(s) may be used to select one or more wavelengths for lasing in a tunable transmitter or transceiver, for example, in a wavelength division multiplexed (WDM) optical system such as a WDM passive optical network (PON). The wavelength-selectable laser device uses a dispersive optical element, such as a diffraction grating, to disperse light emitted from a laser emitter and to direct different wavelengths of the light toward a reflector at different spatial positions such that the wavelengths may be selected by allowing light to be reflected from selected spatial position(s) back into the laser emitter. Thus, the reflected light with a wavelength at the selected spatial position(s) is allowed to complete the laser cavity.