Optical wave guides

Claim 2

An optical wave guide with fluorescing or lasing properties which has a path region formed of a glass composition wherein said glass composition comprises a continuous glass phase having dispersed therein crystallites with fluorescing or lasing properties, wherein the crystallites comprise oxides and phosphates of rare earth metals.

Claim 3

A laser device which comprises an optical wave guide according to claim 1, and means for providing pump frequency radiation into the path region thereof.

Claim 4

An optical amplifier which comprises a laser device according to claim 3, means for providing an input optical signal into its path region and means for extracting amplified signals from its path region.

Claim 5

An optical fibre with fluorescing or lasing properties which fibre has a core formed of a first glass composition and a cladding surrounding said core, said cladding being formed of a second glass composition which has a lower refractive index than said first glass composition wherein said first glass composition comprises a continuous glass phase having dispersed therein crystallites with fluorescing or lasing properties.

Claim 6

An optical fibre with fluorescing or lasing properties which fibre has a core formed of a first glass composition and a cladding surrounding said core, said cladding being formed of a second glass composition which has a lower refractive index than said first glass composition wherein said first glass composition comprises a continuous glass phase having dispersed therein crystallites with fluorescing or lasing properties.

Claim 7

An optical fibre according to claim 4, which has a scatter attenuation of less than 10 dB/m at signal wave length.

Claim 8

An optical fibre according to claim 5, wherein the scatter attenuation is less than 1 dB/m.

Claim 9

A fibre according to claim 4, wherein the crystallites are selected from the group consisting of the oxides and phosphates of rare earth metals.

Claim 10

A fibre according to claim 7, wherein the oxides have the formula X" 2 O 3 where X" represents rare earth metals.

Claim 11

A fibre according to claim 7, wherein the phosphates have the formula X'P 5 O 14 where X' represents rare earth metals.

Claim 12

A fibre according to claim 7, wherein the rare earth metals are selected from Nd, La, Ce, Gd and Y.

Claim 13

A fibre according to claim 7, wherein the crystallites are selected from: ______________________________________ Nd P.sub.5 O.sub.14 La P.sub.5 O.sub.14 Ce P.sub.5 O.sub.14 La.sub.x Nd.sub.(1-x) P.sub.5 O.sub.14 where x is between 0 and 1 Ce.sub.y Nd.sub.(1-y) P.sub.5 O.sub.14 where y is between 0 and 1 [X".sub.z Nd.sub.(1-x) ].sub.2 O.sub.3 where z is 0 to 1 inclusive and X" is selected from La, Gd and Y. ______________________________________

Claim 14

A fibre according to claim 7, wherein the glass composition of the core contains between 1 ppm and 10 5 ppm by weight of the rare earth element.

Claim 15

A fibre according to claim 4, wherein the continuous phase of the first glass composition consists essentially of a mixture of SiO 2 and GeO 2 .

Claim 16

A fibre according to claim 13, wherein the second glass composition consists essentially of SiO 2 .

Claim 17

An optical waveguide suitable for use as an optical laser or amplifier, said waveguide comprising: a core having a continuous glass composition first phase made from a mixture of at least two different glass forming materials to provide said continuous glass composition phase having a first refractive index; said core also having crystallites of rare earth metal oxides or phosphates with fluorescing properties in a second crystalline phase dispersed within said first phase; and a cladding layer of glass composition disposed about said core and having a second refractive index lower than said first refractive index.

Claim 18

An optical waveguide suitable for use as an optical laser or amplifier, said waveguide comprising: a core having a continuous glass composition first phase made from a mixture of at least two different glass forming materials to provide said continuous glass composition phase having a first refractive index; said core also having crystallites of rare earth metal oxides or phosphates with fluorescing properties in a second crystalline phase dispersed within said first phase; and a cladding layer of glass composition disposed about said core and having a second refractive index lower than said first refractive index.

Claim 19

An optical waveguide as in claim 15 wherein said core contains less than 10 5 ppm by weight of said rare earth material.

Claim 20

An optical waveguide as in claim 15 wherein said first phase of the core comprises both GeO 2 and SiO 2 .

Claim 21

An optical waveguide as in claim 15 wherein said first phase of the core comprises at least three components: GeO 2 , P 2 O 5 and SiO 2 .