Annular SP-LPG Fiber Grating for Transmission-Only Multisensing
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Solution Overview
Problem
Current small-period long-period fiber grating (SP-LPG) sensors face challenges in observing weak Bragg resonance peaks, necessitating simultaneous acquisition of reflection and transmission spectra for multi-parameter sensing, which complicates detection steps.
Innovation Solution
An annular SP-LPG sensor with refractive index modulation units arranged as annuli perpendicular to the fiber core axis, processed by a femtosecond laser, allowing simultaneous detection of Bragg resonance peaks and cladding mode resonance peaks in transmission spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If horizontal line-by-line writing method is used to prepare SP-LPG, then the preparation process is simple, but the Bragg resonance peak is too weak to be observed in the transmission spectrum
Solution Approach 1:
The patent transforms the traditional linear grating structure into an annular (circular) grating structure. The refractive index modulation units are arranged in an annular pattern perpendicular to the fiber core axis, creating a curved geometric configuration that enhances light-matter interaction and strengthens the Bragg resonance peak intensity, making it observable in transmission spectrum while maintaining preparation simplicity
Solution Approach 2:
The patent transitions from one-dimensional linear grating writing to two-dimensional annular grating configuration. By arranging modulation units in a circular pattern around the fiber core rather than along a straight line, the grating exploits radial and azimuthal dimensions to enhance coupling efficiency and resonance peak strength without complicating the preparation process
2Adaptability or versatility
If simultaneous acquisition of reflection and transmission spectra is performed for multi-parameter sensing, then both Bragg and cladding mode resonance peaks can be detected, but the detection step complexity increases
Solution Approach 1:
The patent merges the detection of Bragg resonance peaks and cladding mode resonance peaks into a single transmission spectrum measurement. The annular grating structure enables both types of resonance to manifest simultaneously in the transmission mode, eliminating the need for separate reflection and transmission measurements and thereby simplifying the detection workflow while maintaining multi-parameter sensing capability
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 annular design enhances the intensity of both resonance peaks, enabling simultaneous multi-parameter sensing, such as temperature and biochemical molecule detection, with a compact structure and simplified detection steps.
Implementation Method 1
focusing a laser on a fiber core of an optical fiber, setting parameters of the laser and a translation platform, the laser is incident vertically into interiors of the fiber cores, to form the annular SP-LPG sensor
Implementation Method 2
The refractive index modulation units are formed by laser processing
Implementation Method 3
The period of LPG is generally between tens to hundreds of microns, which can couple the fundamental core mode to the cladding modes
Implementation Method 4
The grating is characterized by both the Bragg reflection peak and resonance peaks of the cladding modes
Data Source
AI summary
An annular small-period-long-period fiber grating (SP-LPG) sensor, a preparation method and applications thereof are provided. The annular (SP-LPG) sensor matches the cross-section shape of the optical fibers, the annulus can expand the area of the refractive index modulation region more effectively in the section of the optical fibers, so that the annular grating has a large refractive index modulation region in both the axial and longitudinal directions of the optical fibers, which can simultaneously enhance the intensity of the Bragg resonance peak and the resonance peaks of the cladding modes. Therefore, the Bragg resonance peak and the resonance peaks of the cladding modes can be observed simultaneously in the transmission spectra. It can realize the simultaneous measurement of the refractive index and temperature of the surrounding environment without the need to observe the reflection peak, which simplifies the multi-parameter sensing test steps of the (SP-LPG) sensor.