METHOD OF PRODUCING A DIFFRACTION GRATING ELEMENT

• US 20090224416A1
• Filed: 11/18/2005
• Published: 09/10/2009
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Radiant Opto-Electronics Corp.
• Original Assignee: Nanocomp Oy Ltd.
• Inventors: Laakkonen, Pasi, Levola, Tapani
• Granted Patent: US 8,092,723 B2
• Time in Patent Office: Days
• US Class Current: 264/1.380
• CPC Class Codes: B29D 11/00769 Producing diffraction gratings
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G02B 5/1852 using mechanical means, e.g. ruling with diamond tool, moulding
• CPC Class Codes: G03F 7/0002 Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
• CPC Class Codes: G03F 7/0005 Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor

Abstract

An optical diffraction grating (10) is produced by providing a mold (50) having a plurality of inclined grooves (58), which have a small clearance angle (γ). The mold (50) is covered by a curable material (M1). Said material is subsequently cured, i.e. hardened, and separated from the mold (50) to provide the diffraction grating (10). The inclined orientation of the grooves (58) allows expansion or contraction of the grating during the curing and separation steps such that the probability of mold breakage may be reduced. The inclined orientation of the grooves may also facilitate the separation of the grating (10) from the mold (50).

Claims

1. A method of producing a diffraction grating (10) by using a mold (50), which mold (50) has a plurality of adjacent microscopic grooves (58), the inclination (φ

) of said grooves (58) being greater than or equal to 20 degrees and smaller than or equal to 70 degrees with respect to the normal (N) of the plane of the mold (50), the depth (h) of the grooves (58) being greater than or equal to 0.4 times the grating period (d) of the mold (50), the grating period (d) of said mold (50) being greater than or equal to 0.2 μ

m and smaller than or equal to 10 μ

m, and the clearance angle (y) of said grooves (58) being greater than 0 degrees and smaller than or equal to 20 degrees,

said method comprising at least;

applying an anti-adhesion layer (30) to said mold (50) to facilitate separation of the diffraction grating (10) from said mold (50),

applying curable substance (M1) to said mold (50),

curing said substance (M1) at least partially to produce the diffraction grating (10), and

separating said diffraction grating (10) from said mold (50).

2. The method according to claim 1, wherein the inclination (φ

) of said grooves (58) is greater than or equal to 25 degrees and smaller than or equal to 45 degrees with respect to the normal (N) of the plane of the mold (50).

3. The method according to claim 1, wherein the clearance angle (y) of said grooves (58) is greater than or equal to 5 degrees and smaller than or equal to 12 degrees.

4. The method according claim 1, wherein the filling factor (c2) of the mold (50) is greater than or equal to 0.2 and smaller than or equal to 0.8.

5. The method according to claim 1, wherein the depth (h) of the grooves (58) is greater than or equal to 0.6 times the grating period (d).

6. The method according to claim 1, wherein said substance (M1) is cured by heat.

7. The method according to claim 6 wherein said diffraction grating (10) is separated from said mold (50) when the temperature of the substance (M1) of the grating (10) is greater than or equal to 50°

C.

8. The method according to claim 1 wherein said substance (M1) is cured by UV radiation.

9. The method according to claim 1 wherein said diffraction grating (10) is separated from said mold (50) when the substance (M1) of the grating (10) is in semi-hardened state.

10. The method according to claim 1 further comprising joining a substrate plate (20) to said diffraction grating (10).

11. The method according to claim 10 wherein the diffraction grating (10) is separated from said mold 50 by directing a separating force to the corner and/or edge of said substrate plate (20).

12. The method according to claim 10 wherein said substrate plate (20) is flexible.

13. The method according to claim 10 further comprising treating said substrate plate (20) with an adhesion promoting agent.

14. The method according to claim 1 wherein said mold (50) comprises at least a first groove (58a) having a first inclination (φ

1), and a second groove (58b) having a second inclination (φ

2), said first inclination (φ

1) being different from said second inclination (φ

2).

15. The method according to claim 1 wherein at least one area (A3) of the mold (50) comprises curved and/or circular grooves (58).