- Martin Veis: Magneto-optical interactions in ferrimagnetic garnets
- 9. 12. 2020, 14:10
- online (zoom)
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Abstract:
The current situation in the field of information technology suggests the need for substantial conceptual changes. The rapid development of imaging devices with the ever-increasing resolution, progress in three-dimensional imaging, and implementation of new power consuming software tools, including artificial intelligence, start to put significant demands on improvement in the data transmission, processing and storage. Motivated byrecent rapid development the attentionin optical fiber communication moved towards photonic integrated circuits (PICs), which combine laser sources, modulators, and detectors on one inexpensive silicon platform using well-established and compatible silicon device processing techniques.
For their successful application, PICs would benefit from the integration of magneto-optical isolators. These isolators suppress multiple reflections between the various optical components which could destabilize the laser source, thereby reducing demands on precision manufacturing processes and increasing the efficiency of information transmission. They are taking advantage of magneto-optical phenomena which induce a non-reciprocal phase shift in a resonator or interferometer device, which avoids problems caused by the birefringence of optical waveguides.
A family of ferrimagnetic iron garnets is widely used for fabrication of discrete bulk isolators due to their excellent optical transmission and high magneto-optical response at desired optical wavelengths. However, their integration on PICs is very challenging due to their large lattice parameters and thermal expansion mismatch with conventional silicon technology. When prepared in the form of thin films, garnets usually exhibit noticeably weaker magneto-optical response than in bulk. Moreover, when conventionally deposited on silicon substrates, they exhibit negligible magneto-optical response insufficient for a functional integrated non-reciprocal element.
This talk presents our recent progress in the deposition and characterization of several types of ferrimagnetic iron garnets with various compositions and magnetic anisotropies. A special deposition conditions and post-deposition treatment allowed us to obtain high quality garnet thin films even at silicon substrates with figures of merit exceeding half of bulk values. Moreover, proper analysis of spectrally dependent magneto-optical properties allowed to separate magnetic contributions of particular sublattices and opened new possibilities to properly design particular stoichiometries of ferrimagnetic garnets required by applications.