Magneto-Optic Fiber Sensor for High Sensitivity Magnetic Field Detection
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Solution Overview
Problem
Current magnetic field sensors, such as B-dot sensors, Hall probes, SQUIDs, and atomic vapor cells, face limitations including significant field perturbations, narrow bandwidth, low sensitivity, and operational constraints like cryogenic temperatures, making them unsuitable for accurate high-power microwave testing and evaluation, especially in confined spaces.
Innovation Solution
An ultra-sensitivity optical-fiber magneto-optic field sensor is developed, comprising an input and output fiber with a polarizer and analyzer optically coupled to a magneto-optic crystal element, utilizing flux concentrators and a pump coil to enhance sensitivity, and featuring a removable high-sensitivity module for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If B-dot sensors are used for magnetic field measurement, then the measurement can be performed, but significant field perturbations occur due to metallic components
Solution Approach 1:
The patent replaces metallic mechanical sensing components with an all-optical sensing system. The sensor uses a magneto-optic crystal element that interacts with magnetic fields through optical properties rather than electrical conductivity, eliminating the metallic loop antenna that causes field perturbations in traditional B-dot sensors
Solution Approach 2:
The patent introduces optical fibers as intermediary elements to transmit the magnetic field information. The optical fibers carry light through the magneto-optic crystal, allowing magnetic field measurement without direct electrical or metallic contact with the field, thus avoiding perturbation
2Measurement precision
If SQUIDs are used for high sensitivity measurement, then sensitivity is improved, but the device becomes bulky and requires cryogenic temperatures
Solution Approach 1:
The patent changes the operating temperature parameter from cryogenic (SQUID requirement) to room temperature (optical fiber sensor operation). This parameter change eliminates the need for complex cryogenic cooling systems while maintaining high sensitivity through the magneto-optic effect in the crystal element
Solution Approach 2:
The patent extracts and removes the bulky cryogenic Dewar and superconducting components from the sensing system. By using room-temperature optical fibers and magneto-optic crystals, the system eliminates the large cryogenic infrastructure required by SQUIDs, resulting in a compact portable device
3Measurement precision
If atomic vapor cells are used for sensitive measurement, then sensitivity exceeds SQUIDs, but temperature control requirements limit applications
Solution Approach 1:
The patent uses room-temperature magneto-optic crystal elements that do not require expensive and complex temperature control systems. The optical fiber sensor can be easily deployed and removed without concerns about thermal stability requirements, making it suitable for a broader range of applications including mobile and field measurements
4Measurement precision
If B-dot sensors are used for broadband measurement, then narrow bandwidth is achieved, but multiple sensors are required for broad frequency coverage
Solution Approach 1:
The patent creates a universal magnetic field sensor that can measure across a broad frequency bandwidth using a single device. The optical fiber-based magneto-optic sensor responds to magnetic fields regardless of frequency, eliminating the need for multiple specialized B-dot sensors with complementary bandwidths
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 sensor achieves minimal field perturbation, broad frequency bandwidth, and high sensitivity, enabling accurate magnetic field measurement across a wide range, from very low to intense fields, and is compact, portable, and operates at room temperature, surpassing the limitations of existing technologies.
Implementation Method 1
The sensor includes a magneto-optic crystal element optically coupled between the polarizer and the analyzer... an ultra-sensitivity optical-fiber magneto-optic field sensor
Data Source
AI summary
An ultra-sensitivity optical-fiber magneto-optic field sensor includes an input fiber passing optical power from an optical source into the sensor; a polarizer optically coupled to and downstream of the input fiber; an analyzer optically coupled to and downstream of the polarizer; an output fiber passing optical power out of the sensor to a photoreceiver; and a magneto-optic crystal element optically coupled between the polarizer and the analyzer. The ultra-sensitivity optical-fiber magneto-optic field sensor has an optical axis extending between the input and output fibers along which a beam of optical power is transmitted.