Remarkable robustness of self-imaging distance for a misaligned paraxial Gaussian input and variation in the nonparaxial regime
The variation of focusing distance in a parabolic graded-index slab with the width of a one-dimensional Gaussian input fed at its waist, both axially and misaligned, into the waveguide is studied in paraxial and beyond-paraxial regimes. We obtain analytical expressions, scalable in terms of material...
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Veröffentlicht in: | Journal of the Optical Society of America. B, Optical physics Optical physics, 2023-01, Vol.40 (1), p.127 |
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Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
Online-Zugang: | Volltext |
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Zusammenfassung: | The variation of focusing distance in a parabolic graded-index slab with the width of a one-dimensional Gaussian input fed at its waist, both axially and misaligned, into the waveguide is studied in paraxial and beyond-paraxial regimes. We obtain analytical expressions, scalable in terms of material parameters, for input coupling coefficients for such a Gaussian input. The focusing distance shows remarkable stability for an axially fed input for beam width exceeding the fundamental mode width of the waveguide. There is a smooth variation for the other regime of beam width. In the paraxial domain, we identify a unique beam width of ∼0.76 times the fundamental mode width for which the self-imaging distance is nearly independent of misalignment. The stability, a well-known sharp shift of the focusing point for an axially fed beam of width around that of the fundamental mode, and remarkable stability of self-imaging distance with misalignment at the unique beam width should be useful for efficiency enhancement of device interconnects, sensing, and lensing applications. |
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ISSN: | 0740-3224 1520-8540 |
DOI: | 10.1364/JOSAB.471533 |