# US 7,613,378 B2 · Optical device comprising an optical component and an optical medium with different refractive indices

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 7,613,378 B2
- Document ID: US7613378B2
- Status: Granted
- Kind: B2
- Application number: 11/146,123
- Filed: 2005-06-07
- Published: 2005-12-15
- Granted: 2009-11-03
- Earliest claimed: 2004-06-08
- Assignees: Alcatel
- Inventors: Valérie Girardon; Isabelle Riant; Xavier Bonnet; Alain Fradet; Hervé Lefebvre
- Web page: https://patentgrep.com/patent/US7613378B2

## CPC

- G02B 1/06: made of fluids in transparent cells
- G02B 1/02: made of crystals, e.g. rock-salt, semi-conductors (G02B1/08 takes precedence)
- G02B 6/0239: {Comprising means for varying the guiding properties, e.g. tuning means}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

The present invention consists in an optical device comprising an optical component and an optical medium with different refractive indices, said optical component being at least partly immersed in said optical medium, which device is characterized in that said optical medium contains a salt that is in the liquid state in the range of temperatures at which said optical component is used and stored, i.e. in a range of temperatures generally from −40° C. to +200° C. The optical component may in particular be a Bragg long-period grating (LPG) or a photonic crystal fiber.

## Claims

### Claim 1

An optical device, comprising an optical component and an optical medium that have different refractive indices, and wherein the optical properties of the optical component depend at least in part on the optical medium, said optical medium being external to said optical component and comprising one of (i) a salt that in the absence of a solvent is itself in the liquid state in the range of temperatures at which said optical component is used and stored or (ii) a mixture of salts that in the absence of a solvent other than one of said salts is itself in the liquid state in the range of temperatures at which said optical component is used and stored, and said optical component being at least partly immersed in said optical medium.

### Claim 2 (depends on 1)

A device according to claim 1, wherein said range of temperatures is from −40° C. to +200° C.

### Claim 3 (depends on 1)

A device according to claim 1, wherein said range of temperatures is from −40° C. to +85° C.

### Claim 4 (depends on 1)

A device according to claim 1, wherein said range of temperatures is from −20° C. to +120° C.

### Claim 5 (depends on 1)

A device according to claim 1, wherein said range of temperatures is from −10° C. to +70° C.

### Claim 6 (depends on 1)

A device according to claim 1, wherein said medium consists of a mixture of at least two salts.

### Claim 7 (depends on 6)

A device according to claim 6, wherein said mixture contains a first salt in the liquid state and a second salt dissolved in said first salt.

### Claim 8 (depends on 6)

A device according to claim 6, wherein the composition of said mixture remains stable over time.

### Claim 9 (depends on 1)

A device according to claim 1, wherein said salt or a salt of said mixture of salts contains an anion and a cation.

### Claim 10 (depends on 9)

A device according to claim 9, wherein said anion is selected from a fluoride F—, a chloride Cl—, a bromide Br—, an iodide I—, an aluminochlorate AlClO4—, a perchlorate ClO4—, a tetrafluoroborate BF4—, a hexafluorophosphate PF6—, a hexafluoroarsenate AsF6—, a hydrogenosulfate HSO4—, a trifluoroacetate CF3COO—, a heptafluoro-1-butanoate C3F7COO—, a trifluoromethanesulfonate CF3SO3— (or “triflate” TfO—), a nonafluorobutylsulfonate C4F9SO3— (or “nonaflate” NfO—), a bis-trifluoromethanesulfonimide N(CF3SO2)2— (or Tf2N—), and a bis-trifluoromethanesulfonemethide C(CF3SO2)2— (or Tf2C—).

### Claim 11 (depends on 9)

A device according to claim 9, wherein said cation is selected from ammonium NH4+, sulfonium HSO3+, phosphonium PH4+, lithium Li+, pyridinium C5H5NH+, imidazolium cations (C3H6N2X1X2)+, ammonium cations (X1X2X3X4N4)+, sulfonium cations (X1X2X3S)+, phosphonium cations (X1X2X3X4P)+, and pyridinium cations (X1C5H4NX2)+, where X1, X2, X3, X4 represent aromatic or aliphatic groups.

### Claim 12 (depends on 9)

A device according to claim 9, wherein said salt or said salt of said mixture of salts has for the cation N,N′ dialkylimidazolium with the following general formula, in which R1 and R2 are aliphatic or aromatic groups containing an anion:

### Claim 13 (depends on 12)

A device according to claim 12, where R1 and R2 are similar or different and each contains an anion selected from F—, Cl—, Br—, I—, BF4—, PF6—, AsF6, ClO4—, AlClO4—, CF3COO—, C3F7COO—, CF3SO3—, C4F9SO3—, (CF3SO2)2N—, (CF3SO2)2C—.

### Claim 14 (depends on 12)

A device according to claim 12, wherein R1 and R2 are similar or different and are an aliphatic group selected from methyl —CH3, ethyl —C2H6, propyl —C3H7 and butyl —C4H9.

### Claim 15 (depends on 14)

A device according to claim 14, wherein said salt or said salt of said mixture contains an anion selected from Cl—, Br—, PF6—, BF4—, (CF3SO2)2N—, and C4F9SO3—.

### Claim 16 (depends on 1)

A device according to claim 1, wherein said optical component is a Bragg long-period grating (LPG).

### Claim 17 (depends on 16)

A device according to claim 16, wherein said grating is tuned by modifying the immersion of the optical component in said medium.

### Claim 18 (depends on 16)

A device according to claim 16, wherein the optical response of said grating is substantially constant over said range of temperatures.

### Claim 19 (depends on 18)

A device according to claim 18, wherein said range of temperatures is from −10° C. to +70° C.

### Claim 20 (depends on 1)

A device according to claim 1, wherein said optical component is a length of photonic crystal fiber.

### Claim 21 (depends on 20)

A device according to claim 20, comprising a temperature control unit for controlling the value of the refractive index of the medium.

### Claim 22 (depends on 21)

A device according to claim 21, wherein the temperature control unit is adapted to subject said medium to a temperature from −20° C. to +120° C.

### Claim 23 (depends on 1)

A device according to claim 1, wherein said salt or mixture of salts comprises a room temperature ionic liquid.

### Claim 24 (depends on 1)

A device according to claim 1, wherein said optical medium consists of said salt or mixture of salts.

### Claim 25 (depends on 1)

A device according to claim 1, wherein said medium comprises a salt that in the absence of a solvent is itself in the liquid state over said range of temperatures.

### Claim 26 (depends on 25)

A device according to claim 25, wherein said optical medium comprises a mixture of salts.

### Claim 27 (depends on 25)

A device according to claim 25, wherein said salt has a melting temperature below said range of temperatures.

### Claim 28 (depends on 25)

A device according to claim 25, wherein said salt has a melting temperature no greater than −10°C.