Diamond NV Center Magnetic Sensor Using Absorption
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Solution Overview
Problem
Existing magnetic field sensors using diamonds with nitrogen-vacancy centers have limited sensitivity, with a maximum contrast of 33% or less in detecting magnetic fields due to their reliance on photoluminescence emission.
Innovation Solution
A magnetic field sensor employing a diamond with nitrogen-vacancy centers arranged in an optical resonator, illuminated by a pump laser, utilizes the absorption of infrared radiation by the diamond to detect magnetic fields, increasing sensitivity by using a measuring laser with wavelengths that do not excite singlet states, and featuring an optical resonator with high finesse to minimize losses and enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoluminescence emission is used to detect magnetic fields, then the sensor can determine magnetic field strength, but the sensitivity is limited with a maximum contrast of 33% or less
Solution Approach 1:
Instead of detecting magnetic fields through photoluminescence emission (light output), the patent inverts the approach by detecting through absorption (light input). The sensor measures how much infrared laser light is absorbed by the diamond, which changes with magnetic field strength. This inversion from emission-based to absorption-based detection enables contrast values of 50% or more, surpassing the 33% limit of photoluminescence methods.
2Measurement precision
If a pump laser with wavelength 480 nm to 637 nm is used to illuminate the diamond, then magnetic field-dependent photoluminescence is generated, but the contrast is limited to 33% or less
Solution Approach 1:
The patent changes the wavelength parameter of the illumination source from visible green light (480-637 nm) that excites photoluminescence to infrared light (750-1500 nm) that is absorbed by the diamond. This parameter change in the light wavelength enables direct detection of absorption changes related to magnetic field strength, achieving contrast of 50% or more while avoiding the energy loss limitations of photoluminescence emission.
3Measurement precision
If the diamond is arranged in an optical resonator, then measurement accuracy is enhanced, but device complexity increases
Solution Approach 1:
The optical resonator serves as an intermediary element that enhances the interaction between the infrared laser and the diamond. By placing the diamond within the resonator, the light passes through the diamond multiple times, amplifying the absorption effect and improving measurement accuracy. The resonator mediates the detection process, allowing higher precision without requiring complex detection electronics or additional sensing elements.
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 a significantly higher sensitivity, with a contrast of 50% or more, allowing for more accurate determination of magnetic fields, surpassing the limitations of previous sensors that rely on emitted luminescent radiation.
Implementation Method 1
the absorption of infrared radiation from a measuring laser (5)
Implementation Method 2
at least one optical resonator (3) having a high resonator quality or finesse
Data Source
AI summary
A magnetic field sensor may be provided comprising at least one diamond which comprises at least one nitrogen-vacancy-center. The magnetic field sensor comprises further at least one optical resonator. The diamond is arranged in the optical resonator. At least one pump laser is provided which is configured to illuminate the diamond with laser radiation having a wavelength of about 480 nm to about 637 nm. The sensor comprises further at least one measuring laser configured to illuminate the diamond with laser radiation having a wavelength from 750 nm to 1040 nm or from 1044 nm to 1500 nm, wherein the sensor comprises at least one detector configured to detect the absorption of the laser radiation of the measuring laser in the diamond. Methods are provided for detecting a magnetic field by the magnetic field sensor.