Remote SERS Detection Using Pulsed Laser Excitation
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Solution Overview
Problem
Current remote SERS spectrum detection methods face limitations due to the accumulation of optical fiber Raman effects, particularly with continuous wave excitation light, which reduces sensitivity and restricts the length of optical fiber probes, making them cost-inefficient and labor-intensive.
Innovation Solution
A system utilizing a pulsed laser light source, optical fiber Raman coupling module, and high-speed photodetector for time-resolved spectrum analysis, which limits the accumulated Raman effect within the duration of a pulse, allowing longer optical fiber lengths and improved remote detection capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If continuous wave laser beam is used for Raman excitation, then the optical fiber can transmit the excitation light, but the optical fiber's Raman signal accumulates along the entire optical fiber length, greatly reducing the sensitivity of SERS spectra detection
Solution Approach 1:
The patent uses pulsed laser excitation instead of continuous wave excitation. The pulsed laser emits light in periodic pulses, allowing the Raman signal accumulation to be confined within each pulse duration. This periodic action enables the excitation to continue over time while limiting the accumulation effect to discrete time windows, thereby maintaining detection sensitivity even with long optical fiber lengths.
2Length of stationary object
If the length of optical fiber SERS probe is increased for remote detection, then remote detection capability is improved, but the accumulated Raman effect of the optical fiber severely limits the detection sensitivity
Solution Approach 1:
By using pulsed laser excitation with specific pulse width and repetition rate, the patent confines the Raman signal accumulation to within each pulse duration. This allows the optical fiber length to be extended for remote detection while the accumulated Raman effect remains limited to the pulse width timeframe, thereby maintaining good signal-to-noise ratio even with fiber lengths exceeding 50 cm.
Solution Approach 2:
The patent performs background subtraction by measuring and removing the optical fiber's Raman signal before detecting the SERS signal. This preliminary action of characterizing and eliminating the fiber's Raman background enables the detection of weak SERS signals even through long optical fibers where accumulation would normally occur.
3Length of stationary object
If optical fiber Raman coupling module is used for remote detection, then remote detection is achieved, but each detection point requires one coupling module which is not cost efficient
Solution Approach 1:
The patent integrates the SERS substrate directly onto the optical fiber tip, creating a multi-functional optical fiber SERS probe that combines excitation light transmission, SERS signal generation, and signal collection in a single component. This universal design eliminates the need for separate coupling modules at each detection point, reducing system complexity and cost while maintaining remote detection capability.
4Measurement precision
If SERS substrate is manually placed at the focal point for each detection point, then efficient excitation and coupling is ensured, but the process is time-consuming and labor-intensive
Solution Approach 1:
The patent integrates the SERS substrate directly onto the optical fiber tip, creating a self-contained probe that automatically positions the SERS substrate at the correct location (the fiber tip itself becomes the focal point). This self-service design eliminates the need for manual placement and alignment operations, dramatically improving setup speed and productivity while maintaining efficient excitation and coupling.
Solution Approach 2:
The patent merges the SERS substrate with the optical fiber structure, combining what were previously separate components (fiber, substrate, mounting mechanism) into a single integrated probe. This merging eliminates the manual placement step entirely, as the substrate is permanently positioned on the fiber tip during manufacturing, thereby improving both productivity and reliability.
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 enhances remote detection capability by isolating the optical fiber's Raman background to the pulse width, enabling longer transmission sections and multiple detection points on the same optical fiber path, improving sensitivity and efficiency.
Implementation Method 1
a pulsed laser light source, configured to emit pulsed laser light, the pulsed laser light being used as a Raman excitation light
Implementation Method 2
by forming precious metal nanoparticles or structures on the surface of the optical fiber at the detection point, and utilizing the evanescent wave coupling effect of the optical fiber
Implementation Method 3
the monochromator being connected to the optical fiber Raman coupling module, configured to split the backscattered SERS signal light, to obtain backscattered SERS signal lights at different wavelengths
Implementation Method 4
a high-speed photodetector connected to the monochromator, configured to convert the backscattered SERS signal lights at different detecting positions into time-resolved electrical signals
Data Source
AI summary
A remote SERS spectrum detection system and a method thereof. The system includes: a pulsed laser light source, configured to emit Raman excitation light; an optical fiber Raman coupling module, configured to couple the Raman excitation light; the optical fiber Raman probe, configured to transmit the Raman excitation light to an object to be measured to generate a SERS signal light, a backscattered SERS signal light being coupled to a monochromator through the optical fiber Raman coupling module; the monochromator, configured to split the backscattered SERS signal light, to obtain backscattered SERS signal lights at different wavelengths; a high-speed photodetector, configured to convert the backscattered SERS signal lights into time-resolved electrical signals; a processor, for analyzing electrical signals, retrieving a SERS spectrum of the remote object to be measured, and controlling automatic scanning of a grating in the monochromator to achieve clock synchronization.