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Effect of RI uncertainty in optical waveguides for quantum technology
E Azough1, H Ahmadi1, A Rostami2,3
1Photonics and Nanocrystal Research Lab. (PNRL), University of Tabriz, Tabriz, 5166614761, Iran.
Scientific Reports
|May 8, 2026
Summary
Mode conversion in asymmetric slab waveguides is affected by refractive index inhomogeneity. This study shows that while a bimodal quantum system offers reliable crosstalk length, imperfections significantly reduce it, with wall defects being particularly detrimental.
Area of Science:
- Photonics and Optical Engineering
- Quantum Information Science
- Materials Science
Background:
- Inhomogeneous refractive index in asymmetric slab waveguides causes unwanted mode conversion.
- This mode conversion impacts the performance of quantum systems relying on waveguide modes.
Purpose of the Study:
- To investigate the effects of longitudinal and transverse refractive index inhomogeneity on mode coupling.
- To analyze the impact of these inhomogeneities on quantum crosstalk length.
- To compare the effects of refractive index inhomogeneity with core-clad wall imperfections.
Main Methods:
- Numerical simulation of random errors in refractive index (RI).
- Modeling longitudinal inhomogeneity using phase-match condition with sinusoidal gratings.
- Analysis of bimodal quantum systems utilizing TE0 and TE1 modes.
Main Results:
- Random longitudinal inhomogeneity can be modeled effectively.
- A bimodal quantum system exhibits a reliable quantum crosstalk length under ideal conditions.
- Transverse refractive index imperfections reduce crosstalk length to 250 µm.
- Core-clad wall imperfections severely degrade quantum crosstalk length, reducing it from >30 mm to 11.964 mm.
Conclusions:
- Refractive index inhomogeneity, particularly transverse variations and wall imperfections, significantly impacts quantum crosstalk length in asymmetric slab waveguides.
- Wall imperfections pose a more severe threat to quantum crosstalk length than refractive index inhomogeneity.
- Careful fabrication and control of waveguide structures are crucial for reliable quantum information processing.
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