Optical isolators, reliably integrated on-chip, are crucial components for a wide range of optical systems and applications. We introduce a new class of wideband nonmagnetic and linear optical isolators based on nonlinear frequency conversion and spectral filtering among the pump, signal, and idler wavelengths. The scheme is experimentally demonstrated using difference-frequency generation in periodically poled thin-film lithium niobate integrated devices and short- and long-pass optical filters. We demonstrate a wide bandwidth of more than 150 nm, limited only by the measurement setup, and an optical isolation ratio of up to 18 dB for the involved idler and signal waves. The difference of transmittance at the signal wavelength between forward and backward propagation is 40 dB. We also discuss pathways for substantial isolation improvement using appropriate anti-reflection coatings. The integrable isolator, operating in the telecommunication band, is characterized by a perfectly linear output versus input power dependence and can be incorporated into high-speed telecom and datacom systems as well as a variety of other applications.

中文翻译：

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使用波长转换的线性隔离器

可靠地集成在芯片上的光隔离器是广泛的光学系统和应用中的关键组件。我们基于泵浦，信号和惰轮波长之间的非线性频率转换和光谱滤波，引入了新型的宽带非磁性和线性光学隔离器。该方案在周期极化的薄膜铌酸锂集成器件以及短通和长通滤光器中使用差频产生进行了实验验证。我们展示了超过150 nm的宽带宽，仅受测量设置的限制，所涉及的惰轮和信号波的光隔离比高达18 dB。向前和向后传播之间在信号波长处的透射率差为40 dB。我们还将讨论使用适当的减反射涂层大幅改善隔离的途径。可集成隔离器在电信频段内工作，其特征在于输出功率与输入功率之间具有完美的线性关系，可以集成到高速电信和数据通信系统以及多种其他应用中。