0/-1 order Phase masks (NFH Phase masks)
- for cost-effective fabrication of very low period gratings, typically in high refractive index materials
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 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
Features
It is imperative that the Phase mask is accuracte, uniform and defect-free. Traceability through scientific principles and constants of nature provides absolute pitch accuracy and uniformity.
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 200 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.
Principle
0/-1 order Phase mask principle sketch
The 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.
Product range and Specifications
| Parameter | Specification |
|---|---|
| Grating periods | 200 nm - 600 nm |
| Illumination wavelengths | 193 nm - 435 nm |
| Material | UV grade fused silica |
| Period accuracy | +/- 0.01 nm |
| Period uniformity | +/- 0.01 nm |
| Standard grating sizes | Ø1" |
| Ø2" | |
| Fringe visibility | >98% |
NFH Phase mask Product Specification Sheet
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