Diffractive Optical Multiplexer With Integer Period Gratings

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Solution Overview

Problem

Current optical multiplexers and demultiplexers face challenges in efficiently separating and combining optical signals of different wavelengths without wavelength-dependent angular deflection and signal loss, particularly in telecommunications, due to limitations in diffractive optical elements and spacer materials.

Innovation Solution

The use of first and second transmissive diffractive optical elements with specific grating-normal vector directions and wavevector magnitudes, along with an optical spacer, allows for the transmissive and dispersive diffraction of optical signals, ensuring each wavelength propagates along a distinct beam path without reflection, thereby reducing angular deflection and enhancing signal separation and combination efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional diffractive optical elements are used for wavelength separation, then optical signals can be multiplexed or demultiplexed, but wavelength-dependent angular deflection and signal loss occur

Engineering Contradiction:

Improvesignal separation accuracyVSAvoidsignal loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the physical parameters of the diffractive optical elements, specifically using a first DOE with a first period and a second DOE with a second period that is an integer multiple of the first period. This parameter relationship ensures that diffracted orders from the first element are suppressed by the second element, eliminating wavelength-dependent angular deflection and reducing signal loss while maintaining reliable wavelength separation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If diffractive optical elements with different periods are used, then angular deflection can be reduced, but device complexity increases

Engineering Contradiction:

Improveangular deflection controlVSAvoiddiffractive element configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a universal design where the second diffractive optical element serves multiple functions: it acts as a diffraction grating for wavelength separation and simultaneously functions as a suppressor of unwanted diffracted orders from the first element. The period relationship (integer multiple) enables this dual functionality, controlling angular deflection without requiring additional components, thus managing device complexity while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If multiple diffractive optical elements are implemented, then signal combination efficiency improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvemultiplexing efficiencyVSAvoidgrating period accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent establishes a specific parameter relationship where the period of the second diffractive optical element is an integer multiple of the first element's period. This mathematical relationship simplifies the manufacturing requirements by creating a scalable design - once the first element's period is precisely manufactured, the second element's period can be derived through a simple integer multiple relationship, reducing the overall manufacturing precision burden while maintaining high multiplexing efficiency.

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 configuration effectively separates and combines optical signals of different wavelengths, reducing signal loss and ensuring parallel or evenly spaced demultiplexed beam paths, improving the efficiency and accuracy of optical multiplexing and demultiplexing processes.

Implementation Method 1

be transmissively, dispersively diffracted by the first diffractive optical element

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

The first diffractive optical element includes a multiplexed transmission region characterized by a corresponding average grating-normal vector direction, a corresponding average grating wavevector magnitude, and a corresponding average grating wavevector direction

Methodology Applied

Scientific EffectDispersive diffraction: Diffraction Grating

Data Source

PatentUS9618708B2Multiplexer/demultiplexer based on diffractive optical elements

Publication Date: 2017.04.11 II VI DELAWARE INC

AI summary

A first transmissive diffraction grating includes a multiplexed transmission region; a second diffraction grating includes multiple demultiplexed transmission regions that are spatially displaced from one another and characterized by average corresponding grating-normal vector direction, grating wavevector magnitude, and grating wavevector direction. The demultiplexed transmission regions differ with respect to at least one of those parameters. The gratings are arranged such that each one of multiple optical signals at corresponding different wavelengths co-propagating to the multiplexed transmission region along a multiplexed beam path would: (i) be transmissively, dispersively diffracted by the first diffractive optical element; (ii) propagate directly, without any intervening reflection, between the multiplexed transmission region and a corresponding one of the demultiplexed transmission regions; (iii) be transmissively, dispersively diffracted by the second diffractive optical element; and (iv) propagate from the corresponding demultiplexed transmission region along a corresponding one of multiple demultiplexed beam paths.