Pitch, or the pitch-to-radius ratio κ, is the information-bearing variable. The current optical prototype uses controlled vortex-element adjustment to demonstrate distinguishable states.
3D Modulation is named for the three-dimensional spiral geometry of the structured optical field itself, not a channel count or a mode index. The architecture proposes encoding information by varying that spiral geometry. The pitch-to-radius ratio, κ, acts as the primary information-bearing variable, distinct from selecting an orbital-angular-momentum mode or topological charge. Different controlled spiral-geometric states can produce measurable, distinguishable interference signatures at the receiver. In the broader modulation architecture, these states are associated with controlled variation of pitch and the pitch-to-radius parameter κ.
A coherent optical field is produced.
In the proposed architecture, κ (the pitch-to-radius ratio) is the primary information-bearing variable. The present prototype uses partial rotation of the vortex element to generate the distinguishable experimental states used to investigate this architecture.
Changes in the controlled spiral geometry produce corresponding changes in the optical field and its detected interference signature.
The receiver observes the resulting interference pattern.
Spatial intensity measurements identify the transmitted spiral-geometric state and recover the symbol, without determining an OAM mode index. The broader architecture maps these states to κ.
Conventional OAM-multiplexing research selects and demultiplexes discrete orbital-angular-momentum modes. This architecture instead proposes varying a continuous geometric parameter (κ, the spiral pitch-to-radius ratio) as the primary information-bearing variable, read back through receiver-side ROI analysis. The present experimental demonstration uses a small set of discrete controlled states, not continuous variation. Not limited to OAM mode-index modulation.
In the current laboratory prototype, controlled partial rotation of the vortex element provides the experimental control used to generate distinct spiral-geometric states. The broader modulation architecture is based on controlling spiral pitch, including the pitch-to-radius parameter κ, rather than treating physical rotation itself as the information-bearing variable.
Controlled spiral geometry: variable pitch κ
Prototype: mechanical vortex-element control · Future: SLM · tunable phase element · metasurface · integrated photonics
Equations, the κ–λ relationship, ROI selection, interferometer construction, classifiers, and implementation alternatives are documented in the underlying research and IP, not on this page.