Grating Device with Adjusting Layer

• US 20090059375A1
• Filed: 08/27/2008
• Published: 03/05/2009
• Est. Priority Date: 08/27/2007
• Status: Active Grant

• Current Assignee: Lumela
• Original Assignee: Lumela
• Inventors: Hoose, John
• Granted Patent: US 8,116,002 B2
• Time in Patent Office: Days
• US Class Current: 359/572
• CPC Class Codes: G02B 5/1861 Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence

Abstract

A reflection grating device with a continuous non-reflecting dielectric adjusting layer disposed between a grating structure and one or more continuous reflecting layers is disclosed that operates in an order of interest, such as the 1^st order or 3^rd order of diffraction, with high efficiency and near-exclusion of unwanted orders. Such devices can be employed, for example, in telecommunication and laser applications.

Claims

1. A reflection grating device comprising, in sequence:

a. a grating structure for diffracting an incident radiation wavelength of interest at an angle of incidence normally propagating multiple diffraction orders including a propagated order of interest;

b. a continuous, non-reflecting dielectric adjusting layer adjacent said grating structure wherein said adjusting layer and said grating structure can be optimized to suppress substantially all but the propagated order of interest, and

c. one or more continuous reflecting layers adjacent said adjusting layer for reflecting incident radiation.

2. A grating device as in claim 1 wherein the incident radiation wavelength is in the range from about 1400 nm to about 1550 nm and said dielectric adjusting layer and grating structure can be optimized to suppress all but the 1st order as the propagated order of interest.

3. A grating device as in claim 1 wherein the incident radiation wavelength is either about 193 nm or about 248 nm and said dielectric adjusting layer and grating structure can be optimized to suppress all but the 3^rd order as the propagated order of interest.

4. A grating device as in claims 1, 2 or 3 wherein:

a. the grating structure comprises grooves having two layers each comprising a dielectric material different from the other;

b. the reflecting layer or layers comprise a dielectric material, and

c. the dielectric material of the grating structure, adjusting layer, and reflecting layer each comprises an oxide, nitride, oxinitride or fluoride of an element selected from the group consisting of Group II, Group III and Group IV elements.

5. A grating device as in claim 4 wherein the reflecting layer further comprises a continuous Al, Ag, Cu or Au metal layer in sequence underlying the dielectric reflecting layer or layers.

6. A reflection grating device comprising, in sequence:

a. a grating structure for diffracting an incident radiation wavelength of interest at an angle of incidence normally propagating multiple diffraction orders including a propagated order of interest,

b. a continuous non-reflecting dielectric adjusting layer having a physical thickness substantially unequal to the physical thickness of a ½

wavelength reference layer, wherein said grating structure and adjusting layer can be optimized to suppress substantially all but the propagated order of interest, and

c. one or more continuous reflecting layers adjacent said adjusting layer for reflecting incident radiation.

7. A grating device as in claim 6 designed for the 1^st order as the propagated order of interest, wherein the incident radiation wavelength is in the range from about 1400 nm to about 1550 nm and the physical thickness of said dielectric adjusting layer is about 50% of the physical thickness of said ½

wavelength reference layer.

8. A grating device as in claim 6 designed for the 3^rd order as the propagated order of interest, wherein the incident radiation wavelength is about 193 nm and the physical thickness of said dielectric adjusting layer is about 30% of the physical thickness of said ½

wavelength reference layer.

9. A reflection grating device exhibiting a high efficiency in a propagated order of interest comprising, in sequence:

a. a grating structure for diffracting an incident radiation wavelength of interest at an angle of incidence normally propagating multiple diffraction orders including the propagated order of interest;

b. a continuous non-reflecting dielectric adjusting layer, and

c. one or more continuous reflecting layers adjacent said adjusting layer for reflecting incident radiation.

10. The reflection grating device of claim 9 wherein said grating structure is designed for operation in the 3^rd order as the order of interest at a wavelength of interest of about 193 or 248 nm.

11. The reflection grating device of claim 9 wherein said grating structure is designed for operation in the 1st order as the order of interest at a wavelength of interest of from about 1400 nm to about 1550 nm.

12. The reflection grating device of claim 9 wherein said continuous non-reflecting dielectric adjusting layer has a physical thickness substantially unequal to the physical thickness of a ½

wavelength reference layer

13. A grating device as in claims 10, 11 or 12 wherein:

a. the grating structure comprises grooves having two layers each comprising a dielectric material different from the other;

b. the reflecting layer or layers comprise a dielectric material, and

c. the dielectric material of the grating structure, adjusting layer and reflecting layer each comprises an oxide, nitride, oxinitride or fluoride of an element selected from the group consisting of Group II, Group III and Group IV elements.

14. A grating device as in claim 13 wherein the reflecting layer further comprises a continuous Al, Ag, Cu or Au metal layer in sequence underlying the dielectric reflecting layer or layers.

15. A grating device as in claim 13 having an efficiency of at least 95% in the order of interest.

16. A grating device as in claim 14 having an efficiency of at least 95% in the order of interest.