Comparison between two detection systems for fiber-optic chemical sensor applications

Area of Science:

• Optoelectronics
• Chemical Sensing
• Optical Engineering

Background:

• Fiber-optic sensors are crucial for chemical analysis.
• Traditional spectrographs can be bulky and expensive.
• Alternative detection systems are needed for cost-effective and compact sensors.

Purpose of the Study:

• To compare the performance of a fiber-splitter-based optical detection system against a traditional spectrograph system for fiber-optic chemical sensors.
• To evaluate key performance metrics including stray light, signal-to-noise ratio, spectral resolution, and long-term stability.
• To assess the suitability of the fiber-splitter system for practical applications like CO2 sensing.

Main Methods:

• Two optical detection systems were designed and compared: a single grating spectrograph and a system utilizing 1x3 fiber-optic splitters with interference filters.
• Three types of commercially available 1x3 fiber-optic splitters were tested: fused glass coupler, fused plastic coupler, and a glass fiber-optic bundle.
• Performance metrics such as stray light, signal-to-noise ratio, spectral resolution, and absorbance stability were measured for both systems.
• The systems were applied to a colorimetric CO2 partial pressure sensor to evaluate accuracy and precision.

Main Results:

• Fiber-splitter-based detection systems demonstrated comparable stray light, signal-to-noise ratio, and long-term absorbance stability to the spectrograph system.
• A modest improvement in spectral resolution was observed, increasing from approximately 12 nm for the spectrograph to approximately 6 nm for the fiber-splitter system.
• The fiber-splitter detection systems were significantly smaller in size and lower in cost compared to the spectrograph system.
• Similar accuracy and precision were achieved when both systems were applied to a CO2 partial pressure sensor.

Conclusions:

• Fiber-splitter-based optical detection systems present a viable and advantageous alternative to traditional spectrographs for fiber-optic chemical sensing.
• These systems offer a compelling combination of comparable performance, enhanced spectral resolution, reduced size, and lower cost.
• The findings support the adoption of fiber-splitter detection systems for developing more accessible and efficient chemical sensors.