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0/-1 order Phase masks (NFH)

Phase masks are the production tool used to write gratings in fibers and waveguides. Ibsen Phase masks incorporate unbeatable, interferometric (holographic) patterning technology into a production friendly Phase mask.

– for cost-effective fabrication of very low period gratings, typically in high refractive index materials

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 Suss 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 to required illumination wavelength
  • Phase mask parameters are individually specified – including unique serial number – on each Phase mask
PrincipleThe 0/-1 order principle is advantageous for fine-pitch applications that require completely eliminated unwanted orders. In this geometry, light incident at 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 200 nm.

0/-1 order Phase mask principle sketch

0/-1 order Phase mask principle sketch

Parameter Specification
Grating periods 260 nm – 600 nm
Illumination wavelengths 193 nm – 800 nm
Material UV grade fused silica
Period accuracy +/- 0.01 nm
Period uniformity +/- 0.01 nm
Standard grating sizes Ø1″
Fringe visibility >98%