Interaction of supercontinuum and Raman solitons with microstructure fiber gratings

Area of Science:

• Optics and Photonics
• Nonlinear Fiber Optics
• Materials Science

Background:

• Fiber Bragg gratings (FBGs) are crucial optical components.
• Birefringent microstructured fibers offer unique light-guiding properties.
• Supercontinuum generation involves broadband light generation in optical fibers.

Purpose of the Study:

• To investigate the spectral characteristics of visible supercontinuum light interacting with UV-written FBGs in birefringent fibers.
• To analyze how input pulse power and polarization affect spectral enhancements.
• To understand the underlying physics, including Raman soliton dynamics and dispersive wave generation.

Main Methods:

• Experimental setup involving a birefringent microstructure fiber with UV-written FBGs.
• Characterization of spectral enhancements under varying input pulse power and polarization.
• Numerical modeling using the nonlinear Schrödinger equation (NLSE) with simplified grating dispersion.

Main Results:

• Observed spectral enhancements near the fiber Bragg grating resonance.
• Identified individual Raman solitons for weak input pulses (<0.5 nJ).
• Demonstrated picosecond dispersive wave generation when Raman solitons spatially and spectrally overlap with the grating resonance.
• Numerical modeling successfully reproduced experimental observations, highlighting the role of grating dispersion outside the bandgap.

Conclusions:

• The interaction of supercontinuum light with FBGs in birefringent fibers leads to significant spectral modifications.
• Raman solitons play a key role in generating picosecond dispersive waves.
• Grating dispersion outside the bandgap is critical for understanding these spectral enhancements.
• Numerical simulations provide valuable insights into the complex nonlinear optical phenomena involved.