Simultaneous mode-by-mode impulse response measurement of multi-mode optical systems based on linear optical sampling

Area of Science:

• Optics and Photonics
• Optical Communications
• Fiber Optics

Background:

• Single-mode optical fibers face capacity limitations.
• Multimode optical systems offer potential for increased bandwidth.
• Characterizing multimode systems is essential for their development.

Purpose of the Study:

• To present linear optical sampling as a method for characterizing multimode optical systems.
• To simultaneously measure spectral transfer functions of multiple spatial modes.
• To analyze mode-dependent loss spectra in a multimode transmission line.

Main Methods:

• Utilized linear optical sampling to measure mode-by-mode impulse responses.
• Employed multiplexed impulse responses in series to capture spectral transfer functions.
• Performed singular value analysis on the resulting 6x6 spectral transfer matrix.
• Analyzed mode-dependent loss over a several hundred GHz frequency bandwidth.

Main Results:

• Successfully measured 6x6 spectral transfer functions for a six-spatial-mode transmission line.
• Determined the mode-dependent loss spectrum using singular value analysis.
• Demonstrated the technique's applicability over a broad frequency range.
• Validated linear optical sampling for comprehensive multimode system characterization.

Conclusions:

• Linear optical sampling is a powerful tool for characterizing multimode optical systems.
• The method enables detailed analysis of spectral transfer matrices and mode-dependent loss.
• This technique supports the advancement of multi-spatial-mode fiber systems for higher capacity.
• Essential for overcoming single-mode fiber capacity limits in optical communications.