Observation of transverse coherent backscattering in disordered photonic structures

Area of Science:

• Photonics
• Wave Scattering
• Condensed Matter Physics

Background:

• Coherent backscattering (weak localization) is a phenomenon in disordered systems with multiple coherent-wave scattering.
• Understanding this phenomenon is crucial for various scientific disciplines.

Purpose of the Study:

• To optically implement, observe, and analyze transverse coherent backscattering in (2+1) dimensional randomized photonic systems.
• To investigate the impact of spatial frequency and probe beam coherence on coherent backscattering.
• To establish a versatile experimental platform for studying weak localization.

Main Methods:

• Fabrication of disordered waveguide structures using random-intensity nondiffracting writing.
• Optical implementation and analysis of transverse coherent backscattering.
• Systematic variation of probe wave spatial frequency and spatial coherence.

Main Results:

• Observed and analyzed transverse coherent backscattering in fabricated photonic systems.
• Identified a significant impact of spatial frequency on the strength and shape of the coherent backscattering signal.
• Demonstrated that reducing spatial coherence diminishes localization and coherent backscattering.
• Observed transverse elastic scattering as a precursor to weak localization.

Conclusions:

• The spatial frequency of probe waves critically influences coherent backscattering.
• Spatial coherence is fundamental for observing weak localization.
• The proposed experimental platform allows comprehensive study of coherent backscattering under uncritical conditions.
• Results are transferable to other disordered wave potential systems beyond photonics.