Diffractive Optical Elements (DOEs)

Diffractive optical elements (DOEs) are advanced optical components that are capable of manipulating light by sub-wavelength structures. By incorporating diffractive optics in the optical field of a laser beam, you can control and change the shape of the beams in an energy-efficient manner. This enables a variety of applications with minimal energy loss.

Diffractive Optical Element

Diffractive optical elements and applications

Diffractive optical elements enhance the value of laser systems. They have many functions and are useful for many types of applications. For example, DOEs are used in optical applications like LiDAR ( Light Detection And Ranging) and LADAR (Laser Detection And Ranging) and position sensors and for motion detection.

DOEs and Huygens’ principle

The function of diffractive optical elements is based on the wave nature of light and Huygens’ principle, which states that every point on a wavefront is itself the source of spherical wavelets and the sum of these spherical wavelets forms the wavefront. 

Diffractive optics with a given function follows the same principles as a diffractive grating with a repetitive pattern of two or more levels, formed on the surface of a substrate – typically etched into the surface of a hard substrate or replicated in a polymer on the surface of a substrate or made purely in polymer. The depth of the pattern is in the order of the wavelength of the light, specific to the application, adjusted to the refractive index of the material of the DOE.

1. Master, second image

Diffractive optical elements and how we can help

Diffractive optical elements (DOEs) can be divided into three different categories according to their function: beam splitters, beam shapers, and diffusers (also known as homogenizers).

NIL Technology offers you diffractive optics customized to your specific needs. This enables you to efficiently shape light and to improve the overall performance and flexibility of your products.

Benefits of Diffractive Optics

  • Precise:

We have high-quality production methods and years of experience with high-precision diffraction structures

  • Adaptable:
Easily replace or combine refractive optics with diffractive optics
  • Energy-efficient:
Shape and divide laser beams to control intensity
  • Custom-made:
Customized to your specific needs and specifications
  • Effective:

Be able to precisely control the phase across the aperture and make complex intensity profiles

Masters for diffractive optical elements

We make masters for DOEs in silicon and fused silica. We have no fundamental limits to how deep and how many levels we can make, 16 levels have been demonstrated.

Masters for diffractive optical elements are used directly in the replication process or to generate working molds. In some cases, generations of working molds for volume manufacturing by wafer level replication.

From a DOE master, we can also make Ni molds for use e.g. in an injection molding-based volume manufacturing setup.

Specifications of our masters for diffractive optical elements

  Master material:                           Silicon and fused silica

Height/Depth levels:No fundamental limit (16 levels demonstrated)
Minimum dimension (w):Down to 50 nm
– depending on material, number of levels and aspect ratio
Maximum Aspect ratio (width : height):1:3 to 1:10 (depending on material)
Max substrate diameter:2”, 4”, 6”, 8”
Vertical accuracy between levels:Better than 6%
Overlay accuracy (centre-to-centre) between different layers:Better than 30 nm
Lateral tolerance (same layer) (w):Better than 15 nm

Schematics for DOE Diffusers

DOE diffusers are designed and fabricated to manipulate and control the phase of an input laser beam (typically Gaussian Beam). This is done to be able to generate the desired output pattern with homogenized and uniform intensity. 

As it can be seen in figure, an input laser beam with a Gaussian intensity profile passes through a designed DOE diffuser and the desired output pattern (rectangular flat type intensity, in this case) can be generated at the target plane. 

We support customers from design to fabrication of DOE diffuser with arbitary shape output intensity patter. These include circular and rectangular flat top profiles, diffused line, logos etc. 

Our DOE diffusers are performing with higher levels of efficiency, while they are alignment insensitive to the position of the input beam.