Light Transmission Control via Virtual Reference Field
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Solution Overview
Problem
Existing methods for controlling light transmission through multi-mode optical fibers and biological tissues face issues such as loss of optical power and noise generation due to internal reference path inaccuracies and speckle patterns, which can lead to incomplete characterization of the optical system.
Innovation Solution
A method involving the transmission of light with specific spatial and polarization states through a medium, creation of an optical interference field, and detection of intensity variations to determine optical field amplitudes and phases, allowing for precise control of light transmission without relying on internal reference paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an internal reference path is used for characterizing the optical system, then the method can control light transmission through the medium, but inaccuracies during characterization and loss of optical power occur due to speckle patterns and blind spots
Solution Approach 1:
The patent introduces a virtual reference field as an intermediary concept that avoids the physical limitations of internal reference paths. By using a virtual reference field that does not propagate through the scattering medium, the system eliminates speckle patterns and blind spots while maintaining the ability to characterize the optical system accurately and control light transmission.
Solution Approach 2:
The patent creates a copy of the reference field in the form of a virtual reference field that replicates the necessary reference functionality without the physical constraints. This virtual copy allows the system to perform holographic reconstruction and optical field characterization without the harmful speckle effects of actual internal reference paths.
2Productivity
If phase only analysis is used to concentrate light output from multi-mode fiber, then the method can create spots at the output, but loss of optical power and noise generation occur
Solution Approach 1:
The patent changes the parameter space from phase-only analysis to full complex field analysis by determining both amplitude and phase of the optical field. This parameter expansion allows for more precise control of light concentration, reducing power loss and noise while maintaining the ability to create focused spots at the fiber output.
3Measurement precision
If an intensity detector with very large dynamic range and high resolution is used to detect the reference optical field, then the speckled character with exponential distribution can be detected, but the device complexity and cost increase significantly
Solution Approach 1:
The virtual reference field acts as an intermediary that transforms the detection problem. Instead of requiring high-resolution detection of the highly variable reference field, the virtual reference approach allows standard detectors to suffice by eliminating the extreme intensity variations that would otherwise require complex, expensive detection systems.
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 approach enables accurate characterization and control of light transmission, minimizing power loss and noise, and allows for the creation of desired output optical fields with precise amplitude, phase, and polarization states, even in highly scattering media like multi-mode fibers.
Implementation Method 1
superposing the corresponding output optical field with a reference optical field to create a corresponding optical interference field
Implementation Method 2
detecting an intensity of a spatial portion of a selected polarisation component of the corresponding optical interference field
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
A method for use in controlling light transmission through a medium comprises transmitting light from a single spatial portion of an input optical field through the medium to create an output optical field, superposing the output optical field with a reference optical field to create an optical interference field, detecting an intensity of a spatial portion of a polarisation component of the optical interference field and using the detected intensity to determine a value of an optical field amplitude and a value of an optical field phase for each of a plurality of spatial portions of the input optical field and for each of first and second orthogonal input polarisation states of the transmitted light entering the medium. The method may be used in the control of the transmission of light through a medium which is randomising in amplitude, phase and/or polarisation. The method may be used in the control of the transmission of light through a multi-mode fibre. The method may be used for beam shaping, optical trapping and/or optical manipulation.