0.48NA JTFLH – Ultra-High NA Hard Polymer Clad Fiber for medical, industrial, sensing, and others
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Hard polymer clad silica optical fiber (HPCF) is constructed with a pure silica core, a thin hard polymer cladding that has a lower index of refraction, and a polymer jacket for mechanical and chemical protection. The typical numerical aperture (NA) of the fiber (JTFLH series) is 0.37. Additionally, Polymicro produces an ultra-high NA HPCF (JTFLH 0.48 Series) that has a 0.48NA. HPCF is commonly used in areas like industrial automation, lighting, short distance data-com, sensing, spectroscopy, and disease treatment/clinical diagnostics.

The 0.48NA JTFLH is useful in many applications. For example, in fiber optic sensing, it is usually necessary to collect as much light as possible from the emitting area to improve the signal level. This fiber offers an increased light collection angle or an improved light collecting efficiency, due to its larger NA. In photodynamic therapy, this fiber offers lower optical loss due to bending.

The 0.48NA JTFLH has a low –OH pure silica core1, like the standard JTFLH. The available core sizes are 200μm and larger. The fiber exhibits an excellent transmission in the visible and NIR spectral region (See Figure 1.) The fiber works from -65oC to 125oC and is proof tested from 100 kpsi to 150 kpsi. The 0.48NA JTFLH is jacketed with green Tefzel® that is chemically inert. The fiber is sterilizable and bio-friendly.

Large NA
he 0.48NA JTFLH has a large full-width acceptance cone of 57.4o while the standard JTFLH has 43.4o. In other words, the fiber is capable of collecting nearly 70% more light from common light sources than standard JTFLH and several times as much as silica/silica optical fiber (0.22NA). Given in Table 1 is a comparison of light collection efficiency among the 0.48NA JTFLH, standard JTFLH, and 0.22NA silica/silica optical fiber. As a result of large NA, the 0.48NA JTFLH has a lower bending loss and thus is ideal for space limited applications such as laser surgery.

The cost of the 0.48NA JTFLH fiber is only slightly higher than the standard JTFLH. For the same fiber core size, the 0.48NA JTFLH is more economical than silica/silica optical fiber that uses expensive doped silica performs. It is a good choice for many applications where high power transmission is not required.

The hard clad coating on the fiber is thin and easily damaged. Therefore, the fiber is generally manufactured with a tough, thick Tefzel® jacket for protection. (Other custom jacket materials are also available.) Use of unjacketed hard clad fiber is not recommended.

Summary:

The 0.48NA JTFLH series is an ultra high NA HPCF with low –OH silica core. It is similar to the standard JTFLH, but has a higher numerical aperture. The high NA improves the light collection efficiency and reduces optical loss due to fiber bend. The fiber is ideal for low to medium power applications where the fiber cost is a concern, a large light collection angle or large light distribution angle is needed, and/or the fiber is to be tightly bent. These applications include industrial, sensing, spectroscopy, lighting, and disease treatment/clinical diagnostics.

1. High –OH core version and Nylon and Acrylate jacketing are also available upon request.

Table 1. Comparison of ultra high NA JTFLH with the standard JTFLH and