Custom Slanted Gratings

NIL Technology makes high quality, custom made slanted gratings with extremely high accuracy and excellent uniformity. We understand and appreciate the importance of low tapering, low roughness and distinct shape.

Slanted gratings are one of our specialities and we have extensive experience in making such high-quality gratings. The pitch, the aspect ratio and the slant angle can be tuned to meet your specifications.

Slanted grating
Slanted grating

Slanted gratings in optical applications

Slanted gratings are used in applications, where efficient redirecting of light is important. Currently, the main application of slanted gratings is for transparent waveguides in AR/VR/MR head mounted displays, where light from an image generator is coupled into the waveguide at one end and coupled out of the waveguide and directed to the eye of the observer at the other end. The gratings act as high efficiency in- and out coupling gratings.

Slanted gratings in a waveguide display

Arrangement of slanted gratings in a waveguide display

In addition to waveguides, slanted gratings may be used in any application, where high efficiency of a single diffraction order is desired.

Why choose NIL Technology to make your slanted gratings

NIL Technology specializes in high-precision nanoscale features and complex optical structures. We have made gratings for many years and have ongoing, close relationships with major high-tech companies that use gratings for research & development, innovative new products and mass production.

Our competencies with slanted gratings include:

  • Extreme accuracy
  • Excellent uniformity
  • Flat bottom of the trench
  • Low tapering (parallel walls)
  • Low roughness
  • Distinct shape

NIL Technology is your partner throughout the whole journey, from idea to design and production of the optical part. We offer design, prototyping and manufacturing services, serving both large corporations and academic researchers.

Mastering of high quality gratings

NIL Technology has long and thorough experience in masters. We have refined the manufacturing processes to obtain slanted gratings with high planarity of the slant surfaces, horizontal top and bottom planes, and sharp corners between the surfaces.

Slanted grating masters from NILT do not suffer from rounded corners, warping of the planes, non-parallelism of the slant planes and non-horizontal top and bottom planes, as is the case of less advanced and optimized processed masters. Consequently, masters from NILT provides increased light control, less uncontrolled light scattering and in general second to none performance and efficiency.

Slanted grating master - the pitch, the aspect ratio and the slant angle can be tuned
Slanted master

NILT slanted master with high planarity of the slant surfaces, horizontal top and bottom planes, and sharp corners between the surfaces.

Sub-masters and replication of gratings

The picture below shows a hard replica – a sub-master formed after an original master holding slanted gratings with two different tilt directions separated by only 5 µm. Both slant directions are simultaneously replicated to perfection.

Sub-masters, 1st generation replica

A sub-master of slanted gratings with two opposite slant angles separated by 5 µm.
Pitch: 600 nm, height: 375 nm, tilt angle: 30°.

Devices can be replicated directly from the sub-master or from higher generation sub-masters. The picture below shows 2nd and 3rd generation replications of the slanted grating sub-master. Good fidelity is seen in all generations.

Slanted grating - second generation replica
Slanted grating - third generation

Second and third generation replicas of slanted gratings

Our specifications of sub-masters

Mastering properties
Sub-master material
Hard coating on fused silica (or other substrate)
Tilt angle (offset from vertical)
0-50° demonstrated (accuracy +/- 2°)
Vertical depth
Up to 400 nm demonstrated
Max diameter
6″
Pitch
> 100 nm
Minimun dimension
50 nm
Maximum aspect ration
1 : 3
Parallelism
+/- 1.5 deg
Flatness (bottom)
1 nm
Flatness (top)
5 nm at a depth of 200 nm

Please contact us if you would like more information about what we can do. 

What are slanted gratings anyway?

Slanted gratings are line gratings, where the profile of each line is tilted. It is in the group of gratings such as binary gratings, blazed gratings and multilevel gratings. The optical advantage of slanted gratings is that by proper choice of dimensions, tilt angle and material, almost all the light can be directed into a single diffraction order.         

You can read about blazed gratings underneath, as well as all our optical components: 

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