A general method is presented of evaluating bending losses in hollow-core waveguides; analytic expressions are obtained for metallic hollow, dielectric hollow, and tube leaky waveguides on the basis of the 2-D slab waveguide model. Numerical examples are given for waveguides made of different kinds of metals, oxide, and dielectric materials at 10.6 μm. It is shown that the dielectric tube leaky waveguide can be bent with a small bending radius compared with a metallic hollow waveguide when the guide material is appropriately selected.

Bending losses in hollow and dielectric tube leaky waveguides

Millimeter wave transmission lines are disclosed for propagating electromagnetic waves of a wavelength ranging from about 10 mm to about 0.4 mm. The transmission lines comprise a fiber of co-crystallized thallium bromo-iodide consisting of from about 40 mole percent to about 46 mole percent thallium bromide and from about 60 mole percent to about 54 mole percent thallium iodide. The fiber may be cladded with a dielectric material having a dielectric constant less than that of the fiber. A number of alternate fiber and cladding cross-sectional configurations are disclosed including circular, square, rectangular, and elliptical.

Millimeter wave transmission line using thallium bromo-iodide fiber

1 What Do We Want With Fiber Crystals? An Introductory Overview.- 2 Fundamentals of Growth Dynamics of the ?-Pulling Down Method.- 3 Theoretical Analysis of the Micro-Pulling-Down Process.- 4 Practice of Micro Pulling Down Growth.- 5 Crystal-Chemistry and Fiber Crystal Growth of Optical Oxide Materials.- 6 Oxide Eutectic Crystals for High-Temperature Structural Application.- 7 Oxide Fiber Crystals Grown by ?-PD and LHPG Techniques.- 8 Growth of Micro and Bulk Crystals by Modified Micro-PD and their Properties.

Fiber Crystal Growth From the Melt

A state of the art review of nonsilica based infrared fibers is presented. Two types of fiber materials have been investigated- crystals and glasses. Crystal fiber work appears to be focused on development of short haul CO 2 laser power delivering lines at 10.6 μm. The maximum delivering power of the CW CO 2 laser has reached up to about 100 W by the polycrystalline KRS-5 fiber. A number of glass fibers are being developed in fluorides, sulfides, and heavy metal oxides. The best optical attenuation of each glass fiber has been respectively reduced to 21 dB/km at 2.55 μm for ZrF 4 -based glass fiber with a core-clad structure, 78 dB/km at 2.4 μm for As-S unclad glass fiber, and 13 dB/km at 2.05 μm (70 dB/km at 2.40 μm) for GeO 2 -Sb 2 O 3 glass fiber with a core-clad structure. Recent progress of these infrared fibers offers great potential for new wavelength fiber links operating in the 2-10\mu m region which have not been realized by silica-based fiber.

Infrared optical fibers

Chalcogenide glass fibers for mid-infrared transmission have been fabricated in As-S, As-Ge-Se, and Ge-S glass systems using high purity materials. The preparation of unclad, Teflon FEP clad, and chalcogenide glass clad fibers and their transmission loss characteristics are reported. It is found that appropriate glass compositions for drawing low-loss fibers are limited to the narrow ranges in the glass-forming regions. The minimum losses obtained are 35 dB/km at 2.44μm for As 40 S 60 unclad fiber, 182 dB/km at 2.12 μm for As 38 Ge 5 Se 57 unclad fiber, and 148 dB/km at 1.68 μm for Ge 20 S 80 unclad fiber. It is shown that hydrogen impurity absorptions and short-wavelength weak absorption tails seriously enhance loss in the fibers. It is also suggested that ultralow loss cannot be achieved due to the existence of the weak absorption tail. However, it is expected that the chalcogenide glass fibers can be used in short fiber-length applications such as in the remote monitoring and delivery of CO laser radiation. This is due to their wide operating wavelength ranges of 0.9-6\mu m for As-S, 1.3-9\mu m for As-Ge-Se, and 0.8-5\mu m for Ge-S, in which losses can be reduced to below 1 dB/m.

Chalcogenide glass fibers for mid-infrared transmission

A new type of fiber optical waveguide utilizing TlBr and KRS‐5 has been prepared; its infrared transparency extends to wavelengths well beyond those transmitted by known glassy materials.

A. G. Standlee

Papers

Polycrystalline fiber optical waveguides for infrared transmission

Polycrystalline fiber optical waveguides for infrared transmission