Micro-nano Optical Fiber Sagnac Loop Stability via Filter Mode Control
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Solution Overview
Problem
The stability of output spectra in optical fiber Sagnac loops is a limiting factor in their development for high accuracy and applicability, particularly in sensing processes, due to mode-selective reflection or transmission during light transmission, which affects interference energy concentration.
Innovation Solution
A method involving a micro-nano optical fiber Sagnac loop structure with an optical filter that filters out specific modes, concentrating energy on working modes by cascading the micro-nano optical fiber and optical filter with a 3 dB coupler, ensuring consistent optical path differences to suppress interference and enhance stability without affecting sensor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical filter is added to control modes in the Sagnac loop, then output stability and uniformity are improved, but device complexity increases
Solution Approach 1:
An optical filter is introduced as an intermediary component in the Sagnac loop to selectively control light modes. The filter acts as a mediator that suppresses interference modes while allowing working modes to pass, thereby improving output stability without fundamentally changing the Sagnac interferometer structure
Solution Approach 2:
The optical filter enables parameter changes in the light transmission characteristics by selectively filtering different modes. This allows control over which modes contribute to the interference pattern, changing the effective parameters of the system to achieve better stability while maintaining the core device structure
2Use of energy by moving object
If multiple modes are allowed in the Sagnac loop, then energy distribution is more comprehensive, but output uniformity deteriorates due to interference from multiple modes
Solution Approach 1:
The optical filter extracts and removes unwanted interference modes from the multi-mode light transmission in the Sagnac loop. By taking out the harmful modes while allowing working modes to pass, the system maintains comprehensive energy utilization while achieving uniform output by eliminating mode-related interference fluctuations
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 significantly improves the uniformity and stability of Sagnac loop output spectra, dynamically controlling output characteristics by suppressing interference modes and maintaining sensor performance, as evidenced by reduced spectral fluctuations and unchanged sensitivity.
Implementation Method 1
When light impinges on an optical filter during a transmission process, mode-selective reflection or transmission may occur, thus achieving the effect of filtering and mode selection
Implementation Method 2
When light impinges on an optical filter during a transmission process, mode-selective reflection or transmission may occur, thus achieving the effect of filtering and mode selection
Implementation Method 3
Sagnac effect was firstly proposed by a Frenchman G. Sagnac in 1913. It was firstly used to design fiber gyros which have high sensitivity, fast response, large measuring range and electromagnetic interference immunity
Implementation Method 4
the coupler splits light emitted by the light source into two optical signals of a same frequency which are transmitted clockwise and counterclockwise respectively in the micro-nano optical fiber Sagnac loop
Implementation Method 5
One part of the optical signals is excited by the micro-nano optical fiber to generate cladding modes which couple back to the optical fiber of the micro-nano optical fiber Sagnac loop from the micro-nano optical fiber
Implementation Method 6
differences of optical paths that light transmitted or reflected by the optical filter reaches an aggregation point are to be completely consistent
Data Source
AI summary
The present invention provides a method for realizing high stability of micro-nano optical fiber sagnac loop output by means of filter mode control, and belongs to the field of photoelectric detection technologies. In the present invention, the optical filter is combined with the micro-nano optical fiber Sagnac interference structure so as to control the Sagnac in-loop working mode by use of the mode selection characteristics of the filter. In this way, the interference mode is suppressed to better concentrate energy on the working mode, thereby improving the spectrum output uniformity and stability of the Sagnac loop. Further, the reflection and transmission modes of the optical filter do not participate in interference spectrum output and thus the performance of the system will not be affected. By designing and changing the parameters of the optical filter, the output characteristics of the interferometer can be dynamically controlled.