High-sensitivity, high-frequency extrinsic Fabry-Perot interferometric fiber-tip sensor based on a thin silver...

Area of Science:

• Materials Science and Engineering
• Optical Sensors
• Acoustic Metrology

Background:

• Ultrasonic detection requires sensors with high sensitivity and broad frequency response.
• Existing fiber-optic sensors often face limitations in sensitivity or operational frequency.
• Miniaturized sensors are crucial for in-situ monitoring and minimally invasive medical procedures.

Purpose of the Study:

• To propose and demonstrate a novel fiber-tip sensor for ultrasonic detection.
• To achieve high sensitivity and high-frequency response using an ultra-thin silver diaphragm.
• To explore potential applications in structural health monitoring and medical ultrasonography.

Main Methods:

• Fabrication of an ultra-thin silver diaphragm (300 nm thickness) via vacuum thermal deposition.
• Transfer of the silver diaphragm to the tip of an optical fiber.
• Characterization of the sensor's static pressure sensitivity and resonant frequency.

Main Results:

• The developed fiber-tip sensor exhibits a static pressure sensitivity of 1.6 nm/kPa.
• The sensor achieves a high resonant frequency of 1.44 MHz, enabling high-frequency ultrasonic detection.
• The ultra-thin silver diaphragm (75 μm inner diameter) is key to the sensor's performance.

Conclusions:

• The proposed fiber-tip sensor effectively utilizes an ultra-thin silver diaphragm for sensitive ultrasonic detection.
• The sensor's high resonant frequency and sensitivity make it suitable for demanding applications.
• This technology holds significant promise for advancements in structural health monitoring and medical ultrasonography.