光学参数：

Transmission range: 4 to 16 μm

Refractive index (core): 2.1

Practical NA:  0.5 (bare core)

                     0.35 (core/clad)

                     0.25 (core/clad)

                     0.13 (core/clad)

Damage threshold (CO2 CW): 10 kW/cm2

Reflective loss (l = 10.6 μm) 25%