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What is — and what is not — an optical isolator

The quest for on-chip optical isolators has recently spawned many new isolator structures. However, there has been some confusion about the requirement of nonreciprocity. Here, we review the essential characteristics of an isolator.

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Figure 2: The simplest isolator with two single-mode waveguide ports.
Figure 3


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Correspondence to Alexander Petrov.

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Christopher R. Doerr is working at Acacia Communications Inc.

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Jalas, D., Petrov, A., Eich, M. et al. What is — and what is not — an optical isolator. Nature Photon 7, 579–582 (2013).

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