Wavelength Multiplexer/Demultiplexer Adhesive Mounting for Low Insertion Loss
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Solution Overview
Problem
Conventional wavelength multiplexers/demultiplexers experience increased insertion loss due to changes in environmental temperature, which cause the multilayer film to incline away from or towards the base plate, altering the optical path and increasing reflection loss.
Innovation Solution
The wavelength multiplexer/demultiplexer design includes a base plate with wavelength selective filters fixed by a cured adhesive that does not contact the multilayer film, reducing thermal stress and maintaining the optical path alignment by increasing the adhesive's contact area with the substrate's side and bottom surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the adhesive contacts the multilayer film to fix the wavelength selective filter, then the filter is securely fixed to the base plate, but the multilayer film inclines due to thermal stress when temperature changes, increasing insertion loss
Solution Approach 1:
The adhesive application area is segmented into two distinct zones: the bottom surface of the substrate and the side surface, while explicitly excluding the multilayer film area. This segmentation allows the adhesive to provide secure fixing without causing thermal stress to the multilayer film during temperature changes, thereby preventing inclination and maintaining low insertion loss.
Solution Approach 2:
The adhesive is applied with different properties in different locations: on the bottom surface and side surface of the substrate, the adhesive provides strong bonding and mechanical support, while avoiding contact with the multilayer film ensures thermal stability. This local differentiation of adhesive application quality resolves the contradiction between secure fixing and thermal stress prevention.
2Reliability
If the adhesive contact area with the substrate is increased to reduce thermal stress, then the multilayer film inclination is suppressed, but the adhesive may contact the multilayer film and cause optical path deviation
Solution Approach 1:
The adhesive application area is segmented into two distinct zones: the bottom surface of the substrate and the side surface, while explicitly excluding the multilayer film area. This segmentation allows the adhesive to provide secure fixing without causing thermal stress to the multilayer film during temperature changes, thereby preventing inclination and maintaining low insertion loss.
Solution Approach 2:
The side surface of the substrate acts as an intermediary area that allows the adhesive to provide sufficient bonding area and mechanical support without directly contacting the multilayer film. This intermediary zone enables thermal stress management while preventing optical path deviation by maintaining a clear separation between the adhesive and the optical functional layer.
3Reliability
If the adhesive is applied only on the bottom surface, then the multilayer film is protected from thermal stress, but the fixing strength may be insufficient
Solution Approach 1:
The adhesive application extends from the two-dimensional bottom surface into the third dimension by utilizing the side surface of the substrate. This dimensional extension increases the total adhesive contact area and provides enhanced mechanical anchoring through side bonding, significantly improving fixing strength while maintaining thermal stress resistance by avoiding multilayer film contact.
Solution Approach 2:
The adhesive application area is segmented into two distinct zones: the bottom surface of the substrate and the side surface, while explicitly excluding the multilayer film area. This segmentation allows the adhesive to provide secure fixing without causing thermal stress to the multilayer film during temperature changes, thereby preventing inclination and maintaining low insertion loss.
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 design suppresses the inclination of the multilayer film and reduces insertion loss by minimizing optical path deviation even with temperature changes, ensuring stable signal transmission.
Implementation Method 1
a collimating lens optically coupled to an end portion of the first optical waveguide
Implementation Method 2
The multilayer film is configured to transmit an optical signal in a specific transmission wavelength band and reflect an optical signal in a wavelength band other than the specific transmission wavelength band
Implementation Method 3
Each of the M-number of wavelength selective filters is fixed to the placement surface by a cured adhesive
Data Source
AI summary
A wavelength multiplexer/demultiplexer includes a first collimator, M-number of second collimators, M-number of wavelength selective filters, and a base plate. Each of the wavelength selective filters includes a substrate having optical transparency and a multilayer film. The substrate includes a first main surface and a second main surface, and a bottom surface facing a placement surface of the base plate. The multilayer film is formed on the first main surface and transmits an optical signal in a specific transmission wavelength band and reflect an optical signal in a wavelength band other than the specific transmission wavelength band. Each of the wavelength selective filters is fixed to the placement surface by a cured adhesive. The cured adhesive is in contact with the bottom surface and is in non-contact with the multilayer film in at least one wavelength selective filter among the wavelength selective filters.