Jury members:

Mme Giovanna CALÒ - Rapportrice
M. Xavier LETARTRE - Rapporteur
M. Olivier GAUTHIER-LAFAYE - Examinateur
M. François ROYER - Examinateur
Mme Nathalie BARDOU – Examinatrice

Directeurs de thèse :

Mme Béatrice DAGENS

M. Laurent VIVIEN

Nonreciprocal optical devices, such as isolators and circulators, are essential for controlling light propagation in photonic systems. They prevent feedback-induced instabilities in lasers and enable signal routing for feedback-based processing. As photonic integrated circuits advance, the integration of nonreciprocal devices must keep pace. While magneto-optical isolators excel in compactness, insertion loss, isolation ratio, and spectral bandwidth, their performance in TE polarization remains limited. 
Inspired by magnetobiplasmonic approaches, this work proposes a transverse magneto-optical Kerr effect (TMOKE) coupled-waveguide system. This architecture leverages modal beating and evanescent coupling in silicon waveguides, combined with the magneto-optical (MO) effect, to achieve nonreciprocal operation. Like conventional evanescent couplers, the TMOKE-coupled-waveguide system performs beam division and recombination. With proper tuning, it functions as a 3-dB beam splitter, with outputs that are either in-phase or out-of-phase depending on the propagation direction. Simulations on a silicon platform with a MO garnet demonstrate 30-dB isolation over a 35nm bandwidth and a compact 500µm footprint.