This type of fiber is single-mode over a very broad wavelength range, with a practically constant mode-field diameter (MFD). At short wavelengths, the fibers' performance is limited by macro-bending losses, which determines the practical wavelength range for applications. The F-SM series of fibers are optimized in order to obtain the largest possible MFD without introducing significant macro-bending losses on typical bending radii of more than 16 cm.

The F-SM Series PCFs are typically used where single-mode, high-power delivery is required without introducing non-linear effects. Furthermore, they are the optimal choice for applications requiring single-mode guidance in a very broad wavelength range, e.g. in sensors, spectroscopy, interferometry or RGB displays.

Photonic Crystal Fiber (PCF) can provide characteristics that ordinary optical fiber do not exhibit, such as: single mode operation from the UV to IR with large mode-field diameters, highly nonlinear performance for super continuum generation, numerical aperture (NA) values ranging from very low to about 0.9, optimized dispersion properties, and air core guidance, among others.

Coupling light into and out of an F-SM fiber is as simple as for standard optical fibers. In a free-space set-up, the optics should match the NA of the fiber and be diffraction limited in order to obtain a low-loss coupling. Since the MFD is practically constant, the NA is proportional to the wavelength, which should be considered in the design of coupling optics for a broad wavelength range. The F-SM Series may also be spliced to standard fibers, making them easy to integrate into existing systems or instruments. Optional beam expansion FC connectors enhance high power capabilities.

In order to screen the fibers from microbending losses, the F-SM Series are fabricated with large cladding diameters for the largest core sizes. All fibers have a single-layer acrylate coating, and have been proof tested with a tension of at least 5.0 N.