Athermal AWG MZI Optical Multiplexer Temperature Compensation
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Solution Overview
Problem
Athermal MZI-synchronized AWG optical wavelength multiplexing/de-multiplexing circuits face challenges in perfectly compensating temperature dependence of center transmission wavelength due to second-order temperature components in silica glass waveguides and temperature compensation materials, leading to residual temperature dependence across operating temperature ranges, which affects accuracy and performance, especially in narrow wavelength channel spacing and wide temperature ranges.
Innovation Solution
The optical wavelength multiplexing/de-multiplexing circuit incorporates a phase difference generation coupler with temperature-dependent optical path length differences, modulating the temperature dependence of the Mach-Zehnder interferometer to compensate for remaining temperature dependence in the arrayed waveguide grating, using a temperature-dependent type phase difference generation coupler with grooves and temperature compensation materials to adjust optical path lengths and phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature compensation material is inserted in grooves of the arrayed waveguide grating to compensate for temperature dependence, then the first-order temperature dependence is reduced, but residual second-order temperature dependence remains affecting transmission wavelength accuracy
Solution Approach 1:
The invention divides the temperature compensation function into two independent parts: the arrayed waveguide grating handles first-order temperature dependence compensation through traditional groove structures, while the Mach-Zehnder interferometer separately handles second-order temperature dependence compensation. This segmentation allows each component to optimize for its specific temperature order without interfering with the other, achieving comprehensive temperature compensation across the full range.
Solution Approach 2:
The Mach-Zehnder interferometer acts as an intermediary component that specifically targets and compensates for the residual second-order temperature dependence that the arrayed waveguide grating cannot eliminate. By introducing this intermediate compensation stage, the system achieves complete temperature compensation without requiring the arrayed waveguide grating to handle all temperature orders alone.
2Ease of operation
If athermal AWG design is used to reduce temperature dependence, then temperature adjustment apparatus can be omitted, but residual temperature dependence remains due to second-order temperature components
Solution Approach 1:
The invention merges two different wavelength multiplexing/de-multiplexing technologies - the arrayed waveguide grating and the Mach-Zehnder interferometer - into a single hybrid system. This combination allows the system to maintain the simplicity of athermal design while achieving superior temperature compensation performance that neither component could achieve alone, eliminating residual second-order temperature dependence.
Solution Approach 2:
The invention creates a composite optical system combining silica glass waveguides (for the arrayed waveguide grating) with temperature compensation materials (for the Mach-Zehnder interferometer). This composite structure leverages the complementary temperature compensation characteristics of different materials to achieve complete cancellation of both first-order and second-order temperature dependence effects.
3Loss of energy
If multiple grooves are formed in slab waveguides to reduce radiation loss, then transmission loss is reduced, but device complexity increases
Solution Approach 1:
The invention segments the optical circuit into distinct functional modules - the arrayed waveguide grating module and the Mach-Zehnder interferometer module - each with its own groove structures optimized for specific functions. This modular segmentation allows multiple grooves to be implemented efficiently in each module without creating excessive overall complexity, as each module independently benefits from the radiation loss reduction.
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 achieves a low-loss, high-spectrum flatness optical wavelength multiplexing/de-multiplexing circuit with improved accuracy of center transmission wavelength across a wide temperature range, reducing residual temperature dependence to a minimal variation, enhancing performance and reliability.
Implementation Method 1
The AWG having the reduced temperature dependence of the transmission wavelength is referred to as a temperature independent AWG or athermal AWG. The athermal AWG disclosed in Patent documents 1 and 2 is realized by means of forming a groove which is disposed so as to intersect with the propagation axis of a lightwave in each waveguide (arrayed waveguide or slab waveguide) within the AWG and by inserting material having a refractive index temperature coefficient different from that of the effective refractive index of the waveguide
Implementation Method 2
An arrayed waveguide grating (AWG) utilizing this PLC technology is a circuit realizing optical wavelength multiplexing/de-multiplexing and plays an important role as an optical communication component
Implementation Method 3
a phase difference generation coupler with temperature-dependent optical path length differences, modulating the temperature dependence of the Mach-Zehnder interferometer to compensate for remaining temperature dependence in the arrayed waveguide grating
Data Source
AI summary
An optical wavelength multiplexing/de-multiplexing circuit having a low loss and a flat transmission spectrum is provided. The optical wavelength multiplexing/de-multiplexing circuit compensates a temperature dependence of a center transmission wavelength which remains in an athermal AWG, and has an excellent accuracy of the center transmission wavelength in a whole operating temperature range or has a comparatively wide operable temperature range. The temperature dependence of the transmission wavelength in the athermal MZI is modulated and set so as to cancel the temperature dependence of the center wavelength which remains in the athermal AWG. The present invention focuses particularly on an optical coupler in the MZI and modulates the temperature dependence of the transmission wavelength in the MZI by providing the optical coupler itself with a mechanism which changes a phase difference between two outputs by temperature.