Acousto-Optic Devices for Operation with 2 µm Fiber Lasers

Fiber lasers operating in the 2 µm region are of increasing interest for a range of applications, including laser machining and biomedical systems. The large mode area compared to 1µm fiber lasers combined with operation in an “eye-safe” region of the spectrum makes them particularly attractive. When developing fiber lasers at 1 µm and 1·5 µm manufacturers  were able to call upon enabling technologies used by the telecoms industry, but at longer wavelengths, including 2 µm, many such components are either unavailable or immature.

We report on recent developments of acousto-optic modulators and tunable filters that are specifically optimized for use with fiber systems operating at or around 2µm. AO devices are interesting due to their ability to conserve spatial-coherence, making them appropriate for use with single-mode optical fibers. We describe how the choice of interaction medium is an important consideration, particularly affecting the drive power and the polarization behavior of the device – the latter being an important parameter when used in a fiber system.