Temperature Compensation Device for Electro-Optic Transducer Wavelength Stability
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Solution Overview
Problem
Electro-optical transducers using fiber lasers are sensitive to temperature variations, which cause unwanted changes in the wavelength of the light wave produced, leading to a widening of the light bandwidth and limiting the number of transducers that can be multiplexed on a single optical fiber without signal degradation.
Innovation Solution
A temperature compensation device is introduced, comprising a tubular support element with terminal elements of different thermal expansion coefficients, arranged to create a cavity that varies in length in opposition to the ambient temperature changes, effectively behaving like an element with a negative coefficient of thermal expansion, thereby compensating for the wavelength variations induced by temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fiber laser electro-optical transducers are used for optical signal transmission, then the transducer structure is simple and compact, but the nominal wavelength varies with temperature causing bandwidth widening
Solution Approach 1:
The patent applies thermal expansion by using a compensation element made of material with positive thermal expansion coefficient that is mechanically coupled to the fiber laser cavity. As temperature increases, the compensation element expands, applying mechanical stress to counteract the thermal-induced wavelength drift in the fiber laser, thereby stabilizing the nominal wavelength despite temperature variations.
Solution Approach 2:
The patent employs composite materials by combining the fiber laser cavity with a compensation element made of different material having distinct thermal expansion properties. This composite structure allows the system to leverage the low thermal expansion of the fiber optic material while the compensation element's higher thermal expansion coefficient provides the necessary counteracting mechanical stress to stabilize the wavelength.
2Productivity
If multiple transducers are multiplexed on a single optical fiber to increase sensor capacity, then the number of sensors that can be monitored increases, but temperature-induced wavelength variations cause signal degradation
Solution Approach 1:
The compensation element utilizes thermal expansion to generate mechanical stress that counteracts temperature-induced changes in the fiber laser cavity. This stabilizes the emitted wavelength, ensuring that multiplexed signals from multiple sensors remain distinct and do not overlap, thereby maintaining signal quality and system reliability as more sensors are added.
Solution Approach 2:
The compensation element provides preliminary anti-action by pre-counteracting the thermal drift effects before they can cause wavelength overlap between multiplexed channels. The mechanical coupling ensures that as temperature changes occur, the compensation element immediately applies the opposing stress needed to maintain wavelength separation, preventing signal degradation before it occurs.
3Productivity
If the number of multiplexed transducers is increased to optimize fiber utilization, then the bandwidth efficiency improves, but the light bandwidth occupied by each transducer widens due to temperature sensitivity
Solution Approach 1:
The compensation element exploits thermal expansion to generate mechanical stress that stabilizes the fiber laser cavity dimensions against temperature changes. This prevents the light bandwidth from widening, allowing each transducer to occupy a narrower, more stable wavelength range, thereby increasing the number of transducers that can be multiplexed on a single fiber and improving bandwidth efficiency.
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 stabilizes the nominal wavelength of the light wave produced, reducing the light bandwidth and allowing more transducers to be connected in series on a single optical fiber without signal degradation, enhancing the system's multiplexing capacity and robustness against temperature variations.
Implementation Method 1
the variation in length of the optical fiber element 12 is itself obtained by means of a piezoelectric actuator 18 arranged so as to act on the mechanical tension applied to the optical fiber element 12 as a function of the electrical voltage which is applied to it
Implementation Method 2
The materials constituting the support element and the terminal element respectively being chosen for their respective coefficients of thermal expansion, such that the direction of variations in the length ΔL of said cavity as a function of the ambient temperature θ is of opposite sign to the direction of variation of said ambient temperature
Data Source
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AI summary
The device according to the invention consists of a support member (23) and at least one end element (24), both configured and arranged, relative to each other, such that they form a cavity of length (ΔL) axially limited by two walls, the position of which, relative to each other, varies inversely to the variation in ambient temperature, with a temperature increase causing the walls to move towards one another and vice versa. A linear structure incorporating the device of the invention decreases in length as the temperature increases and vice versa. The invention also relates to electro-optical transducers having a linear-structure piezoelectric actuator that alters the length of an optical fiber segment constituting the laser source of the transducer, and incorporating such a device at the actuator in order to compensate, by adjusting the length of the fiber segment, for the variations in wavelength induced in the laser by the temperature variations.