# US 6,724,968 B2 · Photodefinition of optical devices

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- Number: US 6,724,968 B2
- Document ID: US6724968B2
- Status: Granted
- Kind: B2
- Application number: 09/728,766
- Filed: 2000-12-01
- Published: 2001-10-18
- Granted: 2004-04-20
- Earliest claimed: 1999-12-02
- Assignees: Gemfire Corporation
- Inventors: Hilary S. Lackritz; William K. Bischel; Tony C. Kowalczyk; Simon J. Field; Travis P. S. Thoms; Yeong-Cheng Lee
- Web page: https://patentgrep.com/patent/US6724968B2

## CPC

- G02B 6/12019: {characterised by the optical interconnection to or from the AWG devices, e.g. integration or coupling with lasers or photodiodes (coupling integrated waveguide to fibre G02B6/30, to optoelectronic element G02B6/42; monolithic integration of integrated waveguides with other optical elements G02B6/12004)}
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- G02B 6/12002: {Three-dimensional structures}
- G02B 6/12021: {Comprising cascaded AWG devices; AWG multipass configuration; Plural AWG devices integrated on a single chip}
- G02B 6/12033: {characterised by means for configuring the device, e.g. moveable element for wavelength tuning (switching G02B6/35; thermo-optic devices G02F1/0147)}
- G02B 6/124: Geodesic lenses or integrated gratings
- G02B 6/13: Integrated optical circuits characterised by the manufacturing method
- G02B 6/138: by using polymerisation
- G02B 6/42: Coupling light guides with opto-electronic elements
- G02B 6/02033: {Core or cladding made from organic material, e.g. polymeric material (G02B1/04 takes precedence)}
- G02B 2006/12147: {Coupler}
- G02B 2006/12176: {Etching}
- Y10T 428/31504: Composite [nonstructural laminate]
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An optical structure is fabricated by forming an active layer including a photodefinable material on a substrate or on another underlying layer, forming an upper layer above the active layer, and then patterning the active layer by selective application of radiation through the upper layer. The upper layer is substantially transparent to radiation of the type required to activate the photodefinable material in the active layer.

## Claims

### Claim 1

A radiation-definable material comprising a first layer, a second layer above said first layer, and a third layer above said second layer,
wherein said first, second and third layers each comprise polymers containing unactivated first photosensitive molecules which activate polymerization in response to incident optical energy of a first wavelength,
and wherein said polymer in said second layer further contains a greater concentration by volume of unactivated second photosensitive molecules than does said first and third layers, said second photosensitive molecules activating polymerization in response to incident optical energy of a second wavelength,
said first photosensitive molecules being less susceptible to activating polymerization in response to incident optical energy of said second wavelength than are said second photosensitive molecules, and said second photosensitive molecules being less susceptible to activating polymerization in response to incident optical energy of said first wavelength than are said first photosensitive molecules.

### Claim 2 (depends on 1)

A material according to claim 1, wherein polymerization activated by said second photosensitive molecules in said second layer causes an index of refraction change in said second layer.

### Claim 3 (depends on 1)

A material according to claim 1, wherein said first and third layers comprise cladding layers and said second layer comprises a core layer.

### Claim 4 (depends on 1)

A material according to claim 1, wherein said first, second and third layers all have the same index of refraction.

### Claim 5 (depends on 1)

A material according to claim 1, wherein said material further comprises a fourth layer below said first layer.

### Claim 6 (depends on 5)

A material according to claim 5, wherein said first layer has an index of refraction which is greater than that of said third and that of said fourth layer, and wherein said second layer has an index of refraction which matches said third layer.

### Claim 7 (depends on 1)

A material according to claim 1, wherein said third layer is transparent to radiation of said first type.

### Claim 8 (depends on 1)

A material according to claim 1, wherein said polymer in said second layer is partially crosslinked.

### Claim 9 (depends on 1)

A material according to claim 1, comprising one layer which comprises a polymer containing a greater concentration by volume of unactivated third photosensitive molecules than does another layer of said material, said third photosensitive molecules activating polymerization in response to incident optical energy of a third wavelength,
said third photosensitive molecules being less susceptible to activating polymerization in response to incident optical energy of said first wavelength than are said first photosensitive molecules, and less susceptible to activating polymerization in response to incident optical energy of said second wavelength than are said second photosensitive molecules.

### Claim 10 (depends on 9)

A material according to claim 9, wherein said one layer is said second layer.

### Claim 11 (depends on 9)

A material according to claim 9, comprising a fourth layer between said second and third layers,
wherein said one layer is said fourth layer.

### Claim 12 (depends on 1)

A material according to claim 1, wherein said first layer comprises a mechanical support for said second and third layers.

### Claim 13 (depends on 12)

A material according to claim 12, wherein said mechanical support is flexible.

### Claim 14 (depends on 1)

A material according to claim 1, provided as a roll.

### Claim 15

A method for forming an optical material, comprising the steps of:
forming a second polymer layer above a first layer, said second layer including both first and second types of molecules, said first molecules being more susceptible to activating polymerization in response to incident radiation of a first type than incident radiation of a second type, and said second molecules being more susceptible to activating polymerization in response to incident radiation of a second type than incident radiation of a first type;
exposing said second layer to radiation of said first type but not said second type;
forming a third polymer layer above said second layer; and
curing said third layer without precluding further activation of polymerization by said second molecules in said second layer in response to incident radiation of said second type.

### Claim 16 (depends on 15)

A method according to claim 15, further comprising the steps of:
forming said first layer above a support layer prior to said step of forming a second polymer layer, said first layer comprising a polymer which includes molecules of said first type; and
curing said first layer prior to said step of forming a second polymer layer, said step of curing said first layer comprising the step of exposing said first layer to radiation of said first type.

### Claim 17 (depends on 16)

A method according to claim 16, wherein said step of forming a third polymer layer comprises the step of including molecules of a third type in said third layer, said third molecules activating polymerization in response to incident radiation of a third type, said first and second molecules each being less susceptible to activating polymerization in response to incident radiation of said third type than are said third molecules,
and wherein said step of curing said third layer comprises the step of exposing said third layer to radiation of said third type.

### Claim 18 (depends on 16)

A method according to claim 16, wherein said support layer comprises a flexible web.

### Claim 19 (depends on 16)

A method according to claim 16, further comprising the step of, after said step of curing said third layer, selectively exposing said second layer to radiation of said second type through one of said first and third layers to form an integrated optical index of refraction feature in said second layer.

### Claim 20 (depends on 19)

A method according to claim 19, further comprising the step of, after said step of selectively exposing said second layer to radiation of said second type, exposing said material generally to radiation of said first type.

### Claim 21 (depends on 20)

A method according to claim 20, further comprising the steps of, between said step of curing said third layer and said step of selectively exposing said second layer:
winding said material into a roll;
relocating said roll from a first site to a second site; and
inserting said roll into web processing equipment which performs at least said step of selectively exposing said second layer.

### Claim 22 (depends on 15, 19, 21)

A product made by the method of any of claims 15, 19 and 21.

### Claim 23

A method for patterning an optical stack, comprising the steps of:
providing a material comprising a support layer, a first layer above said support layer, and a second layer above said first layer, said first layer being more susceptible than both said support layer and said second layer to index of refraction changes in response to incident radiation of a first type;
inserting said material into selective exposure equipment; and
selectively exposing said first layer to radiation of said first type through one of said support and second layers to form an integrated optical index of refraction feature in said first layer.