Jacket tube made of synthetically produced quartz glass and optical fibres produced using said jacket tube
Jacket tubes of synthetically produced quartz glass as a semi-finished product for producing an outer cladding glass layer of an optical fiber are generally known. The invention relates to an improvement of a jacket tube in terms of inexpensive producibility and of suitability as a semi-finished product for optical fibers having a low optical attenuation. According to the invention this object is achieved by a jacket tube in which the quartz glass has a content of metastable OH groups of less than 0.05 wt ppm and a content of anneal-stable OH groups of less than 0.05 wt ppm.
1. A jacket tube comprising synthetically produced quartz glass, said jacket tube being made as a semi-finished product configured to be used for producing an outer cladding glass layer of an optical fiber, wherein the quartz glass has a content of metastable OH groups of less than 0.05 wt ppm and a content of anneal-stable OH groups of at least 0.05 wt ppm.
2. The jacket tube according to claim 1 , wherein the quartz glass has a content of metastable OH groups of less than 0.01 wt ppm.
3. The jacket tube according to claim 1 , wherein the quartz glass has a content of anneal-stable OH groups of not more than 5 wt ppm.
4. The jacket tube according to claim 3 , wherein the quartz glass has a content of anneal-stable OH groups of not more than 1 wt ppm.
5. The jacket tube according to claim 3 , wherein the quartz glass has a content of anneal-stable OH groups of not more than 0.5 wt ppm.
6. The jacket tube according to claim 1 , wherein the quartz glass has a content of anneal-stable OH groups of at least 0.1 wt ppm.
7. The jacket tube according to claim 6 , wherein the quartz glass has a content of anneal-stable OH groups of at least 0.3 wt ppm.
8. The jacket tube according to claim 1 , wherein it has a ratio of outer diameter to inner diameter in the range between 2 and 8, preferably between 4 and 6.
9. An optical fiber comprising a core having a diameter d K and a first cladding region cladding the core and having an outer diameter d M , and a second cladding region cladding the first cladding region, the ratio of d M /d K being at least 2.5, wherein the second cladding region consists of synthetic quartz glass obtained by elongation of a jacket tube according to claim 1 .