Multiport swept-wavelength interferometer with laser phase noise mitigation employing a broadband ultra-weak FBG...

Area of Science:

• Optical Engineering
• Metrology and Sensing
• Fiber Optics Communications

Background:

• Optical vector network analyzers (OVNAs) are crucial for measuring optical system transfer functions.
• Laser sweep nonlinearities introduce phase noise, degrading measurements over distance and limiting characterization of long impulse responses.

Purpose of the Study:

• To develop a method to mitigate phase noise distortion in swept-wavelength interferometry.
• To extend the operational range of OVNAs for characterizing complex optical systems.

Main Methods:

• Utilized a densely distributed broadband ultra-weak fiber Bragg grating array.
• Directly measured phase noise distortion at 5-m increments up to 400 m.
• Employed measured data to correct for phase noise-induced distortions.

Main Results:

• Successfully extended the measurement range of swept-wavelength OVNAs beyond 400 m.
• Characterized a 2-km six-mode multimode fiber link with a 20 ns accumulated impulse response.
• Demonstrated direct elimination of phase noise distortion.

Conclusions:

• The developed technique effectively overcomes phase noise limitations in OVNAs.
• Enables accurate characterization of long-haul and high-capacity fiber optic systems.
• Paves the way for advanced optical metrology and sensing applications.