Frequency tunable polarization and intermodal modulation instability in high birefringence holey fiber

Area of Science:

• Nonlinear Optics
• Optical Fiber Communications
• Quantum Optics

Background:

• Parametric amplification in optical fibers is crucial for generating new frequencies.
• Birefringent holey fibers offer unique properties for controlling light propagation.
• Modulation instability (MI) is a key nonlinear phenomenon in fiber optics.

Purpose of the Study:

• To experimentally investigate polarization and intermodal noise-seeded parametric amplification.
• To analyze the generation of modulation instability sidebands in a triple-defect elliptical-core birefringent holey fiber.
• To characterize the spectral shifts of generated sidebands with varying pump wavelengths.

Main Methods:

• Utilizing quasi-Continuous Wave (CW) intense linearly polarized pump pulses.
• Injecting pump pulses parallel and at 45 degrees to the fiber polarization axes.
• Shifting the pump wavelength from 532 nm to 625 nm to observe spectral changes.

Main Results:

• Simultaneous generation of polarization and intermodal modulation instability sidebands was observed.
• Polarization sidebands shifted from 3 THz to 8 THz as pump wavelength increased.
• Intermodal sidebands shifted from 33 THz to 63 THz with increasing pump wavelength.

Conclusions:

• Experimental observations align well with theoretical predictions and phase/group velocity characterizations.
• The study confirms the effectiveness of birefringent holey fibers for controlling parametric amplification.
• This work advances the understanding of nonlinear phenomena in specialty optical fibers.