Experimental Demonstration of Degenerate Band Edge in Metallic Periodically-Loaded Circular Waveguide

Abstract

We experimentally demonstrate for the first time the degenerate band edge (DBE) condition, namely the degeneracy of four Bloch modes, in loaded circular metallic waveguides. The four modes forming the DBE represent a degeneracy of fourth order occurring in a periodic structure where four Bloch modes, two propagating and two evanescent, coalesce. It leads to a very flat wavenumber-frequency dispersion relation, and the finite length structure's quality factor scales as $N^5$ where $N$ is the number of unit cells. The proposed waveguide in which DBE is observed here is designed by periodically loading a circular waveguide with misaligned elliptical metallic rings, supported by a low-index dielectric. We validate the existence of the DBE in such structure using measurements and we report good agreement between full-wave simulation and the measured response of the waveguide near the DBE frequency; taking into account metallic losses. We correlate our finding to theoretical and simulation results utilizing various techniques including dispersion synthesis, as well as observing how quality factor and group delay scale as the structure length increases. Moreover, the reported geometry is only an example of metallic waveguide with DBE: DBE and its characteristics can also be designed in many other kinds of waveguides and various applications can be contemplated as high microwave generation in amplifiers and oscillators based on an electron beam interaction or solid state devices, pulse compressors and microwave sensors.

arXiv comment9 pages, 8 figures

References in corpus (11)

• Gigantic transmission band edge resonance in periodic stacks of anisotropic layers
• Slow light in photonic crystals
• Frozen light in photonic crystals with degenerate band edge
• Oblique frozen modes in periodic layered media
• Giant Gain Enhancement in Photonic Crystals with a Degenerate Band Edge
• Slow wave resonance in periodic stacks of anisotropic layers
• Giant Amplification in Degenerate Band Edge Slow-Wave Structures Interacting with an Electron Beam
• Low Starting Electron Beam Current in Degenerate Band Edge Oscillators
• Strongly Resonant Transmission of Electromagnetic Radiation in Periodic Anisotropic Layered Media
• Theory of Double Ladder Lumped Circuits With Degenerate Band Edge
• Oscillator Based on Lumped Double Ladder Circuit with Band Edge Degeneracy

Cited by in corpus (15)

• Theory of Coupled Resonator Optical Waveguides (CROW) Exhibiting High Order Exceptional Points of Degeneracy
• Exceptional Points of Degeneracy in Periodic Coupled Waveguides and the Interplay of Gain and Radiation Loss: Theoretical and Experimental Demonstration
• The degenerate band edge laser: a new paradigm for coherent light-matter interaction
• Giant resonance and anomalous quality factor scaling in coupled resonator optical waveguides at the degenerate band edge
• General Conditions to Realize Exceptional Points of Degeneracy in Two Uniform Coupled Transmission Lines
• A New Amplification Regime for Traveling Wave Tubes with Third Order Modal Degeneracy
• Exceptional Point of Degeneracy in Backward-Wave Oscillator with Distributed Power Extraction
• Exceptional Degeneracy in a Waveguide Periodically Loaded with Discrete Gain and Radiation Loss Elements
• High Power Backward Wave Oscillator using Folded Waveguide with Distributed Power Extraction Operating at an Exceptional Point
• Oscillator Based on Lumped Double Ladder Circuit with Band Edge Degeneracy
• Experimental Demonstration of a New Oscillator Concept Based on Degenerate Band Edge in Microstrip Circuit
• Triple Ladder Lumped Circuit with Sixth Order Modal Exceptional Degeneracy
• Third Order Modal Exceptional Degeneracy in Waveguides with Glide-Time Symmetry
• Experimental Demonstration of Sixth Order Degenerate Band Edge in Coupled Microstrip Waveguides
• Three-Way Serpentine Slow-Wave Structures with Stationary Inflection Point and Enhanced Interaction Impedance