+1/-1 order Phase masks (FBG Phase masks)
- for easy and cost-effective fabrication of Bragg gratings.
Ibsen's +1/-1 order principle Phase masks ensure quality and facilitate production in the telecommunications, sensor and laser industries. In the production of fiber and waveguide Bragg gratings, the Phase mask is illuminated by a high-power UV laser, typically an excimer laser or frequency-doubled gas laser. Self-interference between the diffracted orders produces the required pitch in the fiber or waveguide.
Any deviation in the Phase mask from the desired grating structure is transferred directly to the waveguide. It is therefore imperative that the Phase mask pitch is accurate, uniform and defect-free. Traceability through scientific principles and constants of nature provides absolute pitch accuracy. In addition, geometric principles in our production equipment ensure strict uniformity, eliminating e-beam drawbacks such as stitching errors and field distortion.
Other important features of our line of +1/-1 order Phase masks are:
- Phase mask pitches for all fiber/waveguide applications, down to 200 nm and through the 1310 and 1550 nm ranges.
- Period accuracy and uniformity better than 0.01 nm.
- Highly suppressed residual zero order (typical: 0-2%).
- Inherently free of stitching errors.
- Continuous linear chirp available.
- Tilted gratings are possible
- Optimized to any illumination wavelength
- Phase mask parameters are individually specified - including unique part number - on each Phase mask.
+1/-1 order Phase mask principle sketch
Using the +1/-1 order principle, the Phase mask is optimized to diffract light equally and maximally into the plus first and minus first orders. Self-interference between these two orders creates an interference pattern with half the pitch of the Phase mask pitch. As the diagram illustrates, a +1/-1 order Phase mask can generate additional unwanted orders. Ibsen Phase masks have highly suppressed zero order noise. The main advantage of this +1/-1 order principle (relative to the 0/-1 order principle) is its ease of use with normally incident illumination.
Product range and Specifications
|Grating periods||400 nm - 2150 nm|
|Illumination wavelengths||193 nm - 800 nm|
|Material||UV grade fused silica|
|Period accuracy||+/- 0.01 nm|
|Period uniformity||+/- 0.01 nm|
|Chirp rates||0 - 20 nm/cm|
|Standard grating sizes||10 mm x 10 mm|
|25 mm x 10 mm|
|50 mm x 10 mm|
|100 mm x 10 mm|
|Guaranteed 0. order suppression||<3% (lower spec optional)|
|Typical 0. order suppression||0-2 %|
|0. order uniformity|
|Grating length 10 mm||+/- 0.5 %|
|Grating length 25 mm||+/- 0.75 %|
|Grating length 50 mm||+/- 1.0 %|
|Grating length 100 mm||+/- 1.0 %|