0/-1 order Phase masks (NFH)
– for cost-effective fabrication of 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 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
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
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 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"
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