0/-1 order Phase masks (NFH)

– for cost-effective fabrication of low period gratings, typically in high refractive index materials
0/-1 order Phase mask

0/-1 order Phase mask

Low-cost production of gratings on planar wafers can be accomplished by use of the Nearfield Holography (NFH) technique, which employs a special type of Phase mask. The Phase mask is made for easy use in a specially modified mask aligner (commercially available from Süss MicroTec) with a conventional UV source as illumination. This technology has distinct production advantages over grating fabrication by direct holography or direct e-beam technology. In addition of fabrication of gratings on semiconductor DFB lasers, the technique is also advantageous in a number of other fine-pitch applications within the telecommunications and sensor industries.

Sample applications include:

  • DFB lasers
  • DBR lasers
  • Integrated planar optics
  • Sensors
  • Biochips


It is imperative that the Phase mask is accurate, uniform and defect-free. Through scientific principles and constants of nature, our fabrication process ensures absolute pitch accuracy.

All our production processes take place in a cleanroom environment, giving you high yield through nearly defect-free Phase masks. Phase masks and the NFH technology are thus suitable for mass production of distributed feedback (DFB) lasers.

Other important features of our line of 0/-1 order Phase masks are:

  • Phase mask pitches down to 260 nm
  • Period accuracy and uniformity better than 0.01 nm
  • Inherently free of stitching errors
  • Optimized for the required illumination wavelength
  • Phase mask parameters are individually specified – including unique serial number – on each Phase mask


0/-1 order Phase mask principle sketch

0/-1 order Phase mask principle sketch

The 0/-1 order principle is advantageous for fine-pitch applications that require complete elimination of unwanted orders. In this geometry, light incident at the Bragg angle is diffracted partially into the minus first order. Self-interference between the minus first order and the undiffracted zero order creates an interference pattern with a pitch equal to the Phase mask pitch. Thus, 0/-1 order Phase masks have half the pitch of the equivalent +1/-1 order Phase masks. Our innovative production techniques allow us to manufacture 0/-1 order Phase masks with periods down to 260 nm.

Product range and Specifications

Grating periods260 nm - 600 nm
Illumination wavelengths193 nm - 800 nm
Material UV grade fused silica
Period accuracy+/- 0.01 nm
Period uniformity+/- 0.01 nm
Standard grating sizesØ1"
Fringe visibility>98%


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Download Product Sheets

pdf_icon NFH Phase Mask Product Specification Sheets