Remarkable robustness of self-imaging distance for a misaligned paraxial Gaussian input and variation in the nonparaxial regime
| Autor: | Subimal Deb, Prasanta K. Panigrahi |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Journal of the Optical Society of America B. 40:127 |
| ISSN: | 1520-8540 0740-3224 |
| DOI: | 10.1364/josab.471533 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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