Samenvatting
Optical systems are usually reciprocal, i.e. the inputs and outputs of the system are interchangeable. However, nonreciprocal optical systems can be found and they are important for specific applications, including optical isolation. Light, incident with an oblique angle on a moving mirror, will be reflected to a different angle, according to the theory of special relativity. In this optical system, the input incident light and the output reflected light are not interchangeable and, consequently, this is a nonreciprocal system. The nonreciprocity is expressed completely in terms of spacetime geometry without the electromagnetic field involved.We show that the same phenomenon can be explained using the Doppler effect in combination with Maxwell's equations rather than using the spacetime geometry. In practice, the moving media can be modeled using transformation optics {1, 2, 3, 4, 5, 6, 7} and the implementation can be carried out with metamaterials {8, 9, 10, 11, 12}. The proposed metamaterial has time-dependent optical parameters.
First, normal incidence on this moving media is investigated by deriving the reflected and transmitted fields in their most general forms, from a monochromatic incident field. This derivation is useful to understand the role of the Doppler effect in this phenomenon. Thereafter, the generalization into oblique incidence verifies the proposed nonreciprocal system.
In conclusion, we have demonstrated that a frequency shift can be obtained from the reflection off a time-dependent medium. In addition, the nonreciprocal response of the obliquely incident light can be used for a scalable implementation of an optical isolator.
| Datum prijs | 2012 |
|---|---|
| Originele taal | English |
| Begeleider | Jan Danckaert (Promotor) |