1. Lens AR coating (three wavelengths available)

Usually, lens materials and AR coatings are optimized for three different wavelength ranges, as shown in the figure.

MW:λ = 3 ‒ 5 µm

MWLW: λ = 3 ‒ 12 µm

LW: λ = 8 ‒ 12 µm

2. Focal Length Selection

In general, coupling light into a hollow-core fiber is relatively simple given the relatively large core. However, if the appropriate focal length optics are not used, both transmission and beam quality will be adversely affected. In general, the beam should enter the fiber directly with a relatively gradual focus. The best coupling into the lowest order mode occurs when the ratio of the focused spot size to the fiber ID is 2ωo/(ID) = 0.64.

Based on the focused beam waist (1/e2 radius):

Best focal length:

The calculation of the best focus assumes an ideal collimated Gaussian input beam, non-ideal beams will have a larger focal spot. Therefore, we recommend choosing a focal length equal to or less than the best focal length. The table provides example recommendations for an input laser beam diameter (D=4 mm) and a fiber inner diameter (ID=300µm).

3. Connector Options

Optical assemblies can provide mating connectors for SMA or FC terminated fiber optic cables.

4.Mounting Options

Coupled optics can be mounted on an optical table (i.e., free space) or directly on a Daylight Solutions laser head. Available free space (FS) versions have metric (M4) or imperial (#8-32) threads for attaching to a column. Our standard Daylight (DL) mount attaches to the laser heads of CW/Pulse, HedgeHog, Unicorn, and Uber Tuner models, and can also be used on mode-free hopping models with an adapter. A different version (DMC) is available for direct mounting to a Daylight MIRcat laser, although this requires manufacturer modifications to the MIRcat housing. If you have any questions, please provide your specific laser model and we will let you know which mount is appropriate. 

5. OAP Assemblies

For high broadband applications, and those where back reflections from AR coated lenses are a concern, we offer optical assemblies that use off-axis parabolic (OAP) reflectors instead of lenses.

Note: OAP assemblies are more difficult to align than lens assemblies. If OAP is required, please inquire about available options.

6. Collimation/focusing components

Guiding Photonics can design custom optics optimized for low divergence output beams leaving hollow fibers. This includes simple single lens designs for collimation, as well as complex high NA multi-element designs for focusing to a diffraction-limited point. 

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