Improved magnet system by multi-objective particle swarm optimization for Faraday rotators

The capability of optical isolation relies heavily on the performance of Faraday Rotator. Especially for miniaturized applications, volume efficient optical isolation is becoming a challenge and has raised widespread attention. The difficulty is enhancing the strength and uniformity of the magnetic field within limited volume. In this study, a novel magnet system that applies to Faraday Rotators is proposed. Compared with traditional approach, our design takes into account both the strength and uniformity of the magnetic field with multi-objective optimization through finite element analysis. An improved model was built based on the traditional Halbach Array for the prove of concept. Results show that, the improved magnet system has achieved a slight improvement in terms of magnetic field strength and has enhanced its uniformity by more than 20%. This method can be applied to various applications by adjusting the constraints during optimization, which pave the way for the further miniaturization of Faraday Rotators.