Raman cascade suppression by using wide band parametric conversion in large normal dispersion regime

Area of Science:

• Nonlinear optics
• Fiber optics

Background:

• Stimulated Raman scattering (SRS) can lead to unwanted spectral broadening and cascade effects in optical fibers.
• Modulation instabilities (MI) significantly influence SRS gain, complicating spectral control.

Purpose of the Study:

• To experimentally suppress complete Raman cascades in a holey fiber.
• To investigate the competition between SRS and parametric processes for spectral control.
• To determine the energy requirements for SRS suppression and its sensitivity to fiber properties.

Main Methods:

• Utilizing two pump wavelengths (532 nm and 1064 nm) placed symmetrically around the fiber's zero dispersion wavelength (ZDW).
• Inducing modulation instabilities to compete with stimulated Raman scattering gain.
• Operating in a large normal dispersion regime.
• Experimentally determining pump energy thresholds for SRS suppression.

Main Results:

• Achieved complete suppression of Raman cascades through gain competition.
• Quantified the energy needed at each pump wavelength for total SRS suppression.
• Evaluated the sensitivity of SRS suppression to the ZDW position.

Conclusions:

• Gain competition between parametric processes and SRS is an effective method for suppressing Raman cascades.
• The presented technique offers a way to control nonlinear spectral generation in optical fibers.
• Understanding the interplay between pump wavelengths, ZDW, and dispersion is crucial for optimizing nonlinear effects.