Optical Waveguide Device UV Light Bias Drift Stabilization
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Solution Overview
Problem
Mach-Zehnder-type optical modulators experience long-term instability due to the photorefractive effect, leading to bias drift and deterioration of optical characteristics when high-power light is input, making it difficult to maintain stable operation and requiring frequent device replacement, which can damage circuit boards.
Innovation Solution
An optical waveguide device with a substrate and electrode, equipped with a light source to irradiate ultraviolet or violet light on the substrate when bias drift exceeds a threshold, effectively eliminating or reducing the photorefractive effect by recombining excited electrons and eliminating static electric fields, thereby stabilizing refractive index changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power light is input to increase optical signal intensity, then propagation distance is extended, but photorefractive effect causes bias drift and characteristic changes
Solution Approach 1:
The patent converts the harmful photorefractive effect into a beneficial self-healing mechanism. By irradiating ultraviolet or violet light (300-450nm) on the substrate, the accumulated space charges are eliminated and refractive index changes are reset, allowing the device to automatically recover from bias drift without manual intervention or replacement
Solution Approach 2:
The patent changes the optical parameter by introducing a specific wavelength range (300-450nm ultraviolet/violet light) to modify the physical state of the substrate. This parameter change eliminates the photorefractive accumulation by exciting electrons back to their original state, thereby resetting the refractive index distribution
2Productivity
If optical modulators operate for long periods, then productivity is maintained, but bias drift occurs due to photorefractive effect
Solution Approach 1:
The patent implements periodic maintenance action by irradiating ultraviolet or violet light at scheduled intervals during operation. This periodic irradiation eliminates accumulated space charges before they cause significant bias drift, enabling long-term stable operation without device replacement
Solution Approach 2:
The patent enables the optical modulator to self-heal by using light irradiation to automatically eliminate its own photorefractive accumulation. The device can restore its own performance characteristics without external intervention, manual adjustment, or replacement
3Reliability
If device replacement is performed to restore characteristics, then reliability is improved, but circuit board damage risk increases
Solution Approach 1:
Instead of physical replacement that risks circuit board damage, the patent uses optical irradiation to convert the degraded state back to a functional state. The ultraviolet/violet light eliminates space charges and restores characteristics in-situ, eliminating the need for device removal and installation
4Reliability
If light irradiation is applied to eliminate photorefractive effect, then bias drift is reduced, but additional energy consumption occurs
Solution Approach 1:
The patent applies light irradiation selectively only when bias drift exceeds a predetermined threshold, rather than continuously. This partial action approach eliminates unnecessary energy consumption while still maintaining reliability by intervening only when needed
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
The device allows for long-term operation by reducing bias drift and maintaining optical modulation characteristics without the need for device replacement, as the photorefractive effect is mitigated through controlled ultraviolet or violet light irradiation, ensuring stable optical performance.
Implementation Method 1
One of the causes for the occurrence of bias drift is bias drift attributed to a photorefractive effect... when high-power light is irradiated on optical materials, electrons at the impurity level and the like in the materials are excited and migrate into light-irradiated regions
Implementation Method 2
Mach-Zehnder-type optical modulators in which lithium niobate (LiNbO3) (also referred to as 'LN'), which is a ferroelectric crystal, is used for substrates... a control electrode for controlling optical waves propagating inside the parallel waveguides by shifting the phases of the optical waves using an electro-optic effect
Data Source
AI summary
An optical waveguide device includes a substrate with an electro-optic effect on which an optical waveguide and an electrode for controlling optical waves propagating through the optical waveguide are formed and at least one light source for irradiating ultraviolet light on the substrate.