Travelling-wave Mach-Zehnder modulators functioning as optical isolators

摘要: On-chip optical isolators not requiring the use of magneto-optical materials has become a long-standing challenge in integrated optics. Here, we demonstrate that traditional travelling-wave modulator can effectively function as an isolator, when driven under prescribed modulation condition. By using off-shelve lithium niobate modulator, achieve more than 12.5 dB isolation over 11.3-THz bandwidth at telecommunication wavelengths with fiber-to-fiber insertion loss 5.5 dB, by employing only single radio-frequency drive signal. We also verify proposed active isolator be functional laser system to prevent instability due strong back reflections. Since modulators are common devices III-V and silicon photonics, our simple but efficient architecture may provide practical solution non-reciprocal light routing photonic circuits.