Fiber-optic power limiter based on photothermal defocusing in an optical polymer

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• High optical power can damage sensitive fiber optic components.
• A need exists for passive, dynamically responsive optical power limiting devices.

Purpose of the Study:

• To characterize the performance of a novel fiber-optic power-limiting component.
• To investigate the underlying photothermal defocusing mechanism.

Main Methods:

• Experimental testing of a passive fiber-optic power limiter.
• Measurement of continuous-wave (CW) power attenuation at 1550 nm and other wavelengths.
• Analysis of the photothermal defocusing mechanism in an optical polymer.

Main Results:

• The device demonstrated dynamic power limiting with up to 9 dB attenuation at 150 mW input power.
• Limiting thresholds were observed around 30 mW (1530-1565 nm) and <10 mW (1430 nm).
• Device performance is dependent on polymer absorption and fiber gap size.

Conclusions:

• The developed fiber-optic component effectively limits optical power using a photothermal mechanism.
• The device shows promise for protecting optical systems from damaging power levels.
• Model calculations show good agreement with experimental results, validating the device's predictive performance.