Hollow Glass Waveguides

Practical Aspects

One of the conveniences of HGWs is that since the core is air, no end polishing is required. To cut a piece of HGW, simply scratch the glass substrate with a SiC or Diamond scribe, and pull. Try not to bend or twist the HGW much while cleaving as this may prevent a clean fracture. A twisting moment could cause a spiral fracture to propagate along the length of the waveguide.

To attain minimum loss it is required that the focused spot size be ~67% of the HGW bore diameter. This ensures proper filling of the air core and minimum attenuation. Since minimum attenuation occurs for the lowest order (TEM00) mode, the performance of the HGW depends strongly on the modal properties of your source. The best results are therefore attained with a high quality laser.

Please be careful when bending the HGWs. While the smaller bore waveguide will bend to quite a tight radius, the larger guides can be quite brittle. The tighter the bend, the greater the strain. Glass is brittle and a great deal of energy is released should the HGW fail under a tight bend. It is strongly recommended you wear eye protection to prevent flying shards of glass from entering your eyes.

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