Custom nonlinearity profile for integrated quantum light sources
Heralded single-photon sources are a fundamental building block for optical quantum technologies. These sources need to be unfiltered and integrated to have good scalability and avoid unnecessary losses. To attain this goal, it is necessary to control the effective nonlinearity seen by the fields as...
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| Format: | master thesis |
| Publication Date: | 2022 |
| Country: | España |
| Institution: | Universitat Politècnica de Catalunya (UPC) |
| Repository: | UPCommons. Portal del coneixement obert de la UPC |
| Language: | English |
| OAI Identifier: | oai:upcommons.upc.edu:2117/377438 |
| Online Access: | https://hdl.handle.net/2117/377438 |
| Access Level: | Open access |
| Keyword: | Nonlinear optics Quantum optics spontaneous parametric down-conversion difference frequency generation adiabatic frequency conversion nonlinear optics quantum optics nonlinear crystals Òptica no lineal Òptica quàntica Àrees temàtiques de la UPC::Enginyeria de la telecomunicació::Telecomunicació òptica |
| Summary: | Heralded single-photon sources are a fundamental building block for optical quantum technologies. These sources need to be unfiltered and integrated to have good scalability and avoid unnecessary losses. To attain this goal, it is necessary to control the effective nonlinearity seen by the fields as they mix and propagate in a waveguide source. In this thesis, we introduce a method to design nonlinear waveguides with arbitrarily shaped effective nonlinearity profiles. The method takes advantage of the fact that the second order nonlinear response is a tensor quantity and thus the local effective nonlinearity of a material depends on the propagation direction of the fields participating in the interaction. Thus, by locally changing the propagation direction of the fields we can modulate the wave-mixing process. Our method allows for the waveguide fabrication process to be significantly simplified: The material structure of the waveguide is made by a single crystal, no longer needing oriented patterning or periodic poling. We use our method to design waveguides with a nonlinearity profile that is Gaussian in the propagation length, allowing to generate perfectly pure heralded single photons. |
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