# US 5,706,379 A · Optical filter for telecommunications

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- Number: US 5,706,379 A
- Document ID: US5706379A
- Status: Granted
- Kind: A
- Application number: 08/530,788
- Filed: 1995-09-19
- Granted: 1998-01-06
- Earliest claimed: 1994-09-28
- Assignees: Sirti S.p.A.
- Inventors: Enrico Serafini; Alberto Zucchinali; Fabrizio Marani; Massimiliano Martino
- Web page: https://patentgrep.com/patent/US5706379A

## CPC

- G02B 6/29368: {Light guide comprising the filter, e.g. filter deposited on a fibre end (G02B6/29359 takes precedence)}
- G02B 6/264: {with optical elements between opposed fibre ends which perform a function other than beam splitting (having lens focusing means G02B6/32; utilising prism or grating G02B6/34)}
- G02B 6/3845: {ferrules comprising functional elements, e.g. filters}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An optical filter comprising two ferrules containing a respective duct internally housing a respective portion of optical fibre; the two ferrules are inserted axially aligned within an alignment bush, between said two ferrules there being inserted a vitreous support on which a layer of optically active filtering material is deposited. A method for constructing said optical filter is also described.

## Claims

### Claim 1

An optical filter comprising two ferrules provided with a respective duct housing internally a respective portion of optical fibre, and into which the two ferrules are inserted axially aligned within an alignment bush, characterised in that between said two ferrules there is inserted a vitreous support on which a layer of optically active material is deposited said vitreous support having two surfaces oblique to the bush axis.

### Claim 2 (depends on 1)

An optical filter as claimed in claim 1, characterised in that said two ferrules are smoothed and lapped at one end, and at their other end comprise a portion of optical fibre.

### Claim 3 (depends on 1)

An optical filter as claimed in claim 1, characterised in that said vitreous support has a cross-section less than the cross-section of each of the two ferrules.

### Claim 4 (depends on 1)

An optical filter as claimed in claim 1, characterised in that said vitreous support has a cross-section greater than the cross-section of each of said portions of optical fibre.

### Claim 5 (depends on 1)

An optical filter as claimed in claim 1, characterised by comprising at least one further alignment bush.