Tunable Optical Add/Drop Multiplexer With Tiltable Mirror
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Solution Overview
Problem
Conventional tunable optical add/drop multiplexers experience intermittent data loss, known as 'data hits,' when tuning between wavelength channels due to the need to rotate both the mirror and thin film filter simultaneously, leading to alignment challenges and signal disruption.
Innovation Solution
A tunable optical add/drop module utilizing a tiltable mirror and a fixed thin film filter, with optical retro-reflectors that maintain the direction and position of the reflected beam fixed, allowing the mirror to tilt independently while adjusting the beam path to minimize coupling loss across all channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both the mirror and thin film filter are rotated simultaneously to tune wavelength channels, then the add/drop function is achieved, but alignment precision deteriorates and signal continuity is disrupted causing data hits
Solution Approach 1:
The patent divides the tuning mechanism into two independent parts: the thin film filter rotates to select different wavelength channels, while the mirror tilts independently to maintain beam alignment. This segmentation allows each component to perform its specific function without compromising the other, eliminating the need for simultaneous rotation and preventing alignment errors.
Solution Approach 2:
Instead of rotating both the filter and mirror together to achieve wavelength tuning, the patent inverts the approach by keeping the mirror stationary in terms of rotation and using only tilt adjustment. The filter handles wavelength selection through rotation, while the mirror handles beam direction through tilt, effectively reversing the conventional simultaneous rotation method.
2Loss of energy
If the mirror tilts to adjust beam path for different wavelength channels, then coupling loss is reduced, but beam position stability deteriorates
Solution Approach 1:
The patent introduces an intermediary mechanism between the mirror tilt and the beam path: the tiltable mirror is positioned such that its tilt axis is offset from the beam path, allowing the mirror to tilt while the beam reflects off a different portion of the mirror surface. This intermediary positioning enables coupling loss reduction through tilt while maintaining beam position stability through geometric compensation.
Solution Approach 2:
The patent transitions from one-dimensional mirror rotation to two-dimensional mirror tilting with offset positioning. By introducing the offset dimension, the system can independently control beam direction (through tilt angle) and beam position (through offset geometry), allowing coupling loss optimization without compromising position stability.
3Adaptability or versatility
If the thin film filter is rotated to select different wavelength channels, then wavelength selectivity is improved, but signal continuity deteriorates causing intermittent data loss
Solution Approach 1:
The patent applies preliminary action by pre-positioning the mirror at the appropriate tilt angle before the filter completes its rotation to the target wavelength channel. This anticipatory mirror adjustment ensures that the beam path is already correctly aligned when the filter reaches its final position, preventing any interruption in signal continuity and eliminating data hits during the tuning transition.
Solution Approach 2:
The patent ensures continuity of useful action by coordinating the mirror tilt and filter rotation such that the beam remains continuously directed toward the correct output port throughout the entire tuning process. The mirror's preliminary tilt adjustment maintains unbroken signal flow, preventing intermittent data loss that would otherwise occur during filter rotation transitions.
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 solution ensures low coupling loss in all ports for add/drop and express channels, reducing data hits and maintaining signal continuity during wavelength tuning, thereby enhancing bandwidth efficiency and service quality.
Implementation Method 1
a tiltable mirror rotatable about a rotation axis to one of a plurality of tilt angles for directing the optical beam along one of a plurality of different paths
Implementation Method 2
a fixed thin film filter (TFF) positioned to receive the input optical beam along any one of the plurality of different paths for splitting the optical beam into a transmittance beam, which includes the at least one drop channel, and a reflection beam
Implementation Method 3
optical retro-reflectors that maintain the direction and position of the reflected beam fixed
Data Source
AI summary
The tunable add/drop multiplexer including a tiltable mirror, a fixed thin film filter, and first and second retro-reflector elements for redirecting express channels back out an input/output port and for redirecting drop channels back out an add/drop port, respectively.