A Broad-band Optical Isolator With Wide-angle Based On One-dimensional Magneto-optical Crystals

Optical isolator is a passive device,which only allows the light transmitting forward. Currently,optical isolator has become one of the key components in the field of optoelectronic technology.Magneto-optical photonic crystal(MPC), incorporating a magnetic layer into a photonic crystal(PC), can improve the effect of Faraday optical rotation of magnetic-optical medium using properties of band gaps and defects of photonic crystals. Therefore, recently, more and more scientists are trying to design Faraday rotor based on one-dimensional magnetic photonic crystal in order to achieve high performance optical isolation.In this paper, we have designed two transmission-type and two reflection-type broad-band optical isolators with wide-angle based on one-dimensional magneto-optical crystals(MPCs).Among them, the basic structure of the transmission-type contains 5 magnetic layers. And the basic structure of the reflection-type contains 3 magnetic layers. The numerical calculations were performed using the transfer matrix. The result shows that, transmittance of the transmission-type isolators can achieve nearly 100% and they have faraday rotation of 45?at the same time. They can realize the optical isolation around 3.1nm with flat-top response. When the incidence angle is between 0-6?, they all can work normally. Similarly, reflection of the reflection-type isolators can achieve nearly 100% and have Kerr rotation of 90?at the same time. They both can realize optical isolation more than 82 nm. When the incidence angle is less than 33.5?, they also can work normally.All structures in this paper can realize broadband isolation, flat-top response and have great tolerance of incidence angle at the same time. They have important practical value in the field of optical communication and optical information processing system.