Optical fibre with fluorescent additive
AssigneeBritish Telecommunications plc
InventorsBenjamin J. Ainslie, Susan P. Craig, Jonathan R. Armitage
Life of this patent
Estimating the term…
Abstract
An optical fibre for use in fibre lasers has the lasing additive eg Er.sup.3+, concentrated in center of the core. Preferably the core has an inner region which contains the additive and an outer region which is dopant free. The concentration of the dopant reduces the pump threshold for a laser and improves the gain performance for a given pump power. The fibre is conveniently made in MCVD. The use of Al.sub.2 O.sub.3 in the inner zone appears to reduce loss of dopant during tube collapse.
Claims21
An optical fibre suitable for forming fluorescent devices, said optical fibre having a cladding, and a core having a longitudinal core axis, said core containing a fluorescent dopant, characterized in that the concentration of the dopant is substantially greater on the core axis than at the interface between the core and the cladding.
An optical fibre which comprises
- (a) a cladding region formed of a first glass composition having a first refractive index;
- (b) an outer core region surrounded by said cladding region and formed of a second glass composition having a second refractive index said second refractive index being higher than said first refractive index;
- (c) an inner core region surrounded by said outer core region and formed of a third glass composition having a refractive index substantially equal to said second refractive index wherein said third glass composition contains a dopant which is capable of undergoing lasing transitions wherein the concentration of said dopant is 0.001 to 10% by weight based on the total third glass composition.
An optical fibre which comprises
- (a) a cladding region formed of a first glass composition having a first refractive index;
- (b) an outer core region surrounded by said cladding region and formed of a second glass composition having a second refractive index said second refractive index being higher than said first refractive index;
- (c) an inner core region surrounded by said outer core region and formed of a third glass composition having a refractive index substantially equal to said second refractive index wherein said third glass composition contains a dopant which provides a rare earth element in a form capable of undergoing lasing transitions wherein the concentration of said dopant is such as to provide 0.001 to 10% by weight of said rare earth element based on the total third glass composition.
An optical fibre which comprises
- (a) a cladding region formed of a first glass composition having a first refractive index;
- (b) an outer core region surrounded by said cladding region and formed of a second glass composition having a second refractive index said second refractive index being higher than said first refractive index;
- (c) an inner core region surrounded by said outer core region and formed of a third glass composition having a refractive index substantially equal to said second refractive index wherein said third glass composition contains a dopant which provides an element selected from Er, Nd, Pr, Ho, Yb and Tm in a form capable of undergoing lasing transitions wherein the concentration of said dopant is such as to provide 0.001 to 10% by weight of said element based on the total third glass composition.
An optical fibre which comprises
- (a) a cladding region consisting essentially of SiO.sub.2 ;
- (b) an outer core region surrounded by said cladding region and consisting essentially of SiO.sub.2 and an additive which increases the refractive index of the SiO.sub.2 ;
- (c) an inner core region surrounded by said outer core region and consisting essentially of SiO.sub.2, an additive which increases the refractive index of the SiO.sub.2 so that the refractive indices of the inner and outer core regions are substantially equal, and a dopant which is capable of undergoing lasing transitions wherein the mole ratio of Si to dopant is between 1:10.sup.-4 and 1:10.
An optical fibre which comprises
- (a) a cladding region consisting essentially of SiO.sub.2 ;
- (b) an outer core region surrounded by said cladding region and having a refractive index greater than said cladding region, said outer core region consisting essentially of SiO.sub.2 and GeO.sub.2 ;
- (c) an inner core region surrounded by said outer core region and having a refractive index substantially equal to said outer core region, said inner core region consisting essentially of SiO.sub.2, Al.sub.2 O.sub.3 and a dopant capable of undergoing lasing transitions.
Dependencies are inferred from the claim text.