Mode-splitting cloning in birefringent fiber Bragg grating ring resonators

Area of Science:

• Photonics
• Optical Resonators
• Fiber Optics

Background:

• Fiber Bragg gratings (FBGs) are key components in optical fiber communications and sensing.
• Ring resonators exhibit complex resonant behaviors influenced by internal and external factors.
• Modal coupling in optical systems can lead to unique spectral features.

Purpose of the Study:

• To theoretically model and experimentally demonstrate a mode-splitting cloning effect in fiber Bragg grating (FBG) ring resonators.
• To investigate the influence of fiber birefringence and FBG reflectivity on modal coupling.
• To explore the potential of this effect for spectroscopic sensing applications.

Main Methods:

• Development of a theoretical model for resonant coupling between polarized modes in FBG ring resonators.
• Experimental implementation using weakly birefringent FBG ring resonators.
• Analysis of resonator transmission spectra to observe mode-splitting phenomena.

Main Results:

• Demonstration of a single split-mode resonant structure in the absence of birefringence due to degeneracy removal.
• Observation of a secondary split doublet, creating a 'clone' of the initial split mode, in the presence of FBG birefringence.
• Confirmation that modal coupling strength is dependent on fiber birefringence and FBG reflectivity.

Conclusions:

• The study successfully reports the theoretical and experimental evidence of a mode-splitting cloning effect.
• This effect arises from resonant coupling between different polarization modes in FBG ring resonators.
• The observed complex split-mode dynamics offer potential for novel spectroscopic-sensing applications.