Compact integrated one-way magnetophotonic crystal mirror

By exploiting the concepts of magnetic group theory we show how unidirectional behavior can be obtained in two-dimensional magneto-photonic crystals (MOPhC) with uniform magnetization. This group theory approach generalizes all previous investigations of one-way MOPhCs including those based on the use of antiparallel magnetic domains in the elementary crystal cell. Here, the theoretical approach is illustrated for one MOPhC example where unidirectional behavior is obtained by appropriately lowering the geometrical symmetry of the elementary motifs. In this way we prove how a PhC be obtained that has a band gap in only one direction and not in the opposite. One-way transmission is numerically demonstrated for a photonic crystal slice. Using this concept a novel design is obtained for a very compact integrated optical isolator. For an isolation extinction ratio better than 20dB the total device length is limited to 40 crystal periods (which in the telecom frequency domain amounts to only 20–30 micrometer) In this same frequency domain the operation bandwidth is as large as several 100GHz. It will be shown how the device can be further optimized and how its design is flexible with respect to the used crystal motif. Fabrication tests are underway and first experimental data can hopefully be presented.