Fiber-optic silicon Fabry-Perot interferometric bolometer with improved detection limit for magnetic confinement...

Area of Science:

• Plasma physics
• Fusion energy
• Optical diagnostics

Background:

• Fiber-optic bolometers (FOBs) are crucial for measuring plasma radiation in magnetic confinement fusion.
• Previous FOB designs utilized silicon pillars as both Fabry-Perot interferometers (FPIs) and radiation absorbers, limiting detection sensitivity.

Purpose of the Study:

• To develop an improved FOB design with enhanced detection sensitivity for plasma radiation measurement.
• To engineer the FOB absorber to achieve higher temperature rise and improved responsivity.

Main Methods:

• Designed a novel FOB incorporating a gold disk as the primary radiation absorber attached to a silicon FPI.
• Developed a fabrication method for the gold-disk FOB.
• Characterized FOB performance, including noise, responsivity, response time, and noise-equivalent power density (NEPD).

Main Results:

• The gold-disk FOB demonstrated a responsivity of ~2.8 mK/(W/m²) and an NEPD of 0.13 W/m².
• These results represent a >9x increase in responsivity and a 6x reduction in NEPD compared to previous silicon-only absorber designs.
• The gold disk provides superior x-ray absorption and temperature rise compared to silicon.

Conclusions:

• The engineered gold-disk absorber significantly enhances FOB sensitivity and reduces NEPD.
• This improved FOB design offers better performance for plasma radiation measurement in magnetic confinement fusion.
• The design shows promise for broader applications in fusion energy research due to its improved sensitivity and absorption characteristics.