Intensity modulation of broadband optical signals transmitted through large-core fiber-optic cables often resorts to opto-mechanical choppers, usually in the form of bulky rotating wheels. We demonstrate an alternative fiber-optic intensity modulator with a compact footprint of 55.6 × 12.8 × 4.6 mm3 that can be integrated in-line in an optical system. The design comprises two optical fiber cantilevers separated by a small air gap. The optical modulation is achieved by controlling the transverse offset between the cores of the input and output fibers using a piezoelectric actuator. The demonstrated implementation can be used as a quasi-static attenuator down to 0 Hz or an arbitrary waveform modulator up to 400 Hz, providing 30-dB modulation contrast across the complete fiber transmission range. The feasibility of this device is demonstrated in a fiber-based remote pyrometry sensor using lock-in detection in the 2 to 2.5-μm infrared band, where the thermal radiation collected by a multi-mode optical fiber with a 360 μm core is modulated at 390 Hz. The resulting noise-equivalent temperature difference is demonstrated to be better than 0.6°C for object temperatures above 35°C.

中文翻译：

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用于大芯径、高数值孔径多模光纤的全光纤强度调制器

通过大芯光纤电缆传输的宽带光信号的强度调制通常采用光机械斩波器，通常采用笨重的旋转轮的形式。我们展示了另一种光纤强度调制器，其占地面积为 55.6 × 12.8 × 4.6 mm3，可以在线集成到光学系统中。该设计包括由小气隙隔开的两个光纤悬臂。光调制是通过使用压电致动器控制输入和输出光纤纤芯之间的横向偏移来实现的。演示的实现可用作低至 0 Hz 的准静态衰减器或高达 400 Hz 的任意波形调制器，在整个光纤传输范围内提供 30-dB 调制对比度。该设备的可行性在基于光纤的远程高温计传感器中得到证明，该传感器使用 2 至 2.5 微米红外波段的锁定检测，其中由具有 360 微米纤芯的多模光纤收集的热辐射在390赫兹。对于高于 35°C 的物体温度，所产生的噪声等效温差被证明优于 0.6°C。