Features

Endlessly Single Mode Operation - No Higher Order
Mode Cut-Off
Handles Very High Average Power
as well as High Peak Power
Low Nonlinearities
Low Fiber Loss
Mode Field Diameter is Wavelength Independent
Available with Core Sizes from 12 to 35 μm

Applications

Delivery of High-Power Broadband Radiation
in a Single Spatial Mode
Short Pulse Delivery
Mode Filtering
Laser Pigtailing
Multiwavelength Guidance
Sensors and Interferometers

Thorlabs offers a selection of Endlessly Single Mode (ESM), Large Mode Area (LMA) photonic crystal fibers. A conventional single mode fiber is actually multimode for wavelengths shorter than the second-mode cutoff wavelength, limiting the useful operating wavelength range in many applications. In contrast, Crystal Fibre's endlessly single mode Photonic Crystal Fibers (PCFs) are truly single mode at all wavelengths for which fused silica is transparent. In practice, the useful operating wavelength range is limited only by bend loss. Although the cladding possesses six-fold symmetry, the mode profile is very similar to the quasi-Gaussian fundamental mode of a conventional, axially symmetric, step-index fiber, resulting in a form overlap that is >90%. Unlike conventional fibers, these fibers are fabricated from a single material - undoped, high-purity, fused silica glass. The combination of material and very large mode area enables high power levels to be transmitted through the fiber without material damage or the adverse effects caused by the fiber's nonlinear properties.

The fibers can be spliced to standard single mode fibers or directly connectorized with standard FC/PC connectors or SMA 905 high power connectors. They can also be offered with end sealing or connectors as a custom item. Please contact your local Tech Support office for details or to receive a quotation.

Item #	ESM-12-01	LMA-20	LMA-25	LMA-35
Optical Properties
Mode Field Diameter*	10 ± 1 µm	15.0 ± 1.5 μm	19.8 ± 2 μm	26.0 ± 0.5μm
Attenuation**	<1 dBm/km @1550 nm <15 dBm/km @1384 nm <4 dBm/km @1060 nm	<0.007 dB/m @780 nm	<3.5 dB/km @1064 nm <1.5 dB/km @1550 nm	<0.01 dB/m @1550 nm
Numerical Aperture	0.1 ± 0.05 @1550 nm	0.041 ± 0.01 @780 nm 0.055 ± 0.01 @1064 nm	0.04 ± 0.01 @1064 nm 0.046 ± 0.01 @1550 nm	<0.01 dB/m @1550 nm
Mode Field Area	80 ± 15 µm²	~175 µm²	~265 µm²	~530 µm²
Physical Properties
Signal Core Diameter	12 ± 1 µm	20.0 ± 0.4 μm	25.2 ± 0.4 μm	35.0 ± 0.5 μm
Outer Cladding Diameter, OD	125 ± 3 µm	229.5 ± 5 μm	268 ± 5 μm	283 ± 5 μm
Coating Diameter	240 ± 15 µm	340 ± 10 μm	410 ± 10 μm	426 ± 10 μm
Cladding Material	Pure Silica
Coating Material	Acrylate, Single Layer
Proof Test Level	0.5%	-	-	-

*Full width at points in the near field where intensity has dropped to 1/e of the peak value.

**Measured for a bend radius of 16 cm

ESM-12-01

ESM-12

LMA-25

LMA-20

LMA-35

This application note addresses general handling of fibers from NKT Photonics, including how to strip the protective coating and how to cleave the fibers and tips for coupling light to and from the fibers. This is ideal for customers new to photonic crystal fibers.

Application_Note-_Stripping_Cleaving_&_Coupling.pdf

The application note below addresses general advice about fusion splicing of photonic crystal fibers (PCFs). The note is limited to the work related directly to the fusion splicer, whereas guidelines for general handling of the PCFs can be found in the application note to the left.

Application Note-_Splicing_Single Mode_PCF.pdf

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Posted Comments:
Poster: acable	Posted Date: 2008-06-04 14:35:46.0
One trick, obvious once said, is to ensure that the coupled light field is focused in air in front of the fiber. This ensures that the first waist that forms within the fiber is highly aberrated from the first bounce at the core cladding interface. This results in a lower power density than would be realized if the light field is focused directly on (worst case) or near the outer face of the fiber.

Poster: Tyler	Posted Date: 2008-06-04 14:11:20.0
A response from Tyler at Thorlabs to Daniel: As you know, many factors can influence the power damage threshold. In general, these fibers can be treated similarly to bulk silica, but in practice, things like imperfect coupling, contaminants, and other factors reduce the damage threshold. Each LMA fiber has a different mode field area and thus would have a different damage threshold. A good guideline would be to determine the mode field area and limit the power so that the peak power density is less than the damage threshold of silica, which is on the order of 400GW/cm^2. For safety, a factor of 10 or so might be prudent to use when using the fiber.(i.e, use 40GW/cm^2 as the maximum power density) I know this doesnt really answer your question but there are currently many good people in the industry trying to really understand and quantify damage thresholds so it is not at all a parameter than can be given with precision or guaranteed. If your application will utilize power densities in excess of 40 GW/cm^2 please contact an application engineer at Thorlabs to discuss the products feasibility and to gain access to any recent feedback concerning the damage threshold of the product. To the reader: If you have any experience with the damage threshold of Large Mode Area Fibers please consider posting to this page. It is Thorlabs hope that this forum can become a valuable source of information for the scientific community.

Poster: daniel.mclean	Posted Date: 2007-11-19 12:18:39.0
It would be good if you listed the power handling capability of these fibers.