Phase Modulator Using 45-Degree Polarization Preserving Fiber Winding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photosensors with phase modulators suffer from reduced accuracy due to light intensity modulation and error phase differences caused by uneven mechanical stress and resonance phenomena, leading to ineffective phase modulation and measurement inaccuracies.
Innovation Solution
A phase modulator design that employs polarization preserving fibers wound at a 45-degree angle relative to mechanical stress directions, minimizing light transmission loss differences between axes and using specific fiber types like panda-type or bow-tie fibers with reduced lateral load-induced phase changes, along with protective coatings and vibration-absorbing materials to mitigate external stress and resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If polarization preserving fiber is randomly wound around piezoelectric element, then phase modulation function is achieved, but light intensity modulation occurs and measuring accuracy deteriorates
Solution Approach 1:
The patent applies asymmetry by precisely controlling the winding angle of the polarization preserving fiber relative to the piezoelectric element's stress direction. Instead of random winding, the fiber is wound at a specific angle (typically 45 degrees) to ensure symmetric stress distribution on both polarization axes, thereby eliminating differential intensity modulation while maintaining phase modulation functionality.
2Measurement precision
If polarization preserving fiber is wound around piezoelectric element, then phase modulation is achieved, but propagation constant difference changes causing light loss in one axis
Solution Approach 1:
The patent changes the winding angle parameter of the polarization preserving fiber to optimize performance. By setting the winding angle to 45 degrees relative to the piezoelectric element's stress axis, the stress is evenly distributed between the two polarization axes, preventing excessive propagation constant differences and minimizing light loss in either axis while maintaining effective phase modulation.
3Measurement precision
If fiber coil is used in photosensor, then optical signal transmission is achieved, but resonant vibration occurs causing error phase difference
Solution Approach 1:
The patent converts the potentially harmful resonant vibration into a beneficial effect by designing the fiber coil's resonant frequency to match the desired measurement frequency range. The resonant vibration is utilized to enhance the sensitivity of the sensor to specific frequency ranges, while damping structures are added to control and limit excessive vibrations that would cause error phase differences.
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 configuration enhances measurement accuracy by minimizing light intensity modulation and error phase differences, ensuring effective phase modulation and robust resistance to external vibrations and thermal shocks.
Implementation Method 1
a piezoelectric element (11) and a polarization preserving fiber (12) which is wound around the piezoelectric element (11) in such a way that directions (12a, 12b) of light propagation axes of the fiber (12) form about 45 degrees relative to directions (11a to 11d) of mechanical stress of the cylindrical piezoelectric element (11)
Implementation Method 2
a propagation constant difference between two light propagation axes of the polarization preserving fiber changes to cause phase modulation to light
Data Source
Figure 1~2(d)
Figure 3~4
Figure 5~7
AI summary
The present invention provides a photosensor that uses a phase modulation technique for optical detection and conducts a highly accurate measurement. The photosensor uses a phase change difference of light propagated through a polarization preserving fiber with respect to tensile stress and employs proper polarization preserving fibers for a phase modulator 10, light-transmitting polarization preserving fiber 23, and coil-shaped polarization preserving fiber 30, to achieve a highly accurate measurement.