- Diffraction of single order only (+1st order, RHC)
- 0th order (LHC) is undiffracted
- Diffracted order is always orthogonal to input
- RHC -> LHC
- Efficiency: Up to 90% diffraction efficiency through a waveguide
- Max Efficiency for single grating: Near 99%
- Field of View:
- >80° in direction of diffraction
- >100° diagional
- Requires very high index waveguide
- Subwavelength Grating Periods for VIS and IR
- Minimum Grating Period: <300nm
- Grating Thickness: ~2um
- Can be tuned for Narrow or Wideband use
- Size: up to 300 x 300mm sq; round samples custom
Telecom Blazed Gratings
- >90% Efficiency
- Can be made reflective with reflective substrate
BPGs are the only technology for holographic waveguides that give unparalleled efficiency, coupled with single order and single polarization diffraction, that operates over an extraordinary wide field of view (FOV). These gratings can also be implemented with an efficiency gradient that helps with color and brightness uniformity. These aspects make the BPG ideal for use in augmented reality. One polarization can be used with high efficiency over a large FOV to convey the overlayed information and the other polarization (external view from the outside world) can come through without distortion.
- Higher efficiency
- Large angle of operation
- Can be tuned to operate over full band with high efficiency
Any desired angle of incidence (e.g., in=0۠) can be waveguided by selecting the proper slant angle G and period Λ.
Diffraction angle Θ1 must follow grating equation, where nin and nout are refractive
FAQs about BPGs
Q. What is the smallest grating period you can make?
A. We are currently able to fabricate down to 300nm. We are working to reduce this further.
Q. Will your technology work with other waveguide technologies, such as surface relief?
A. Yes. We have successfully combined our in-coupling BPGs and a surface relief out-coupling grating.
Q. What is the field of view (FOV) that is possible with BPGs?
A. We can achieve up to ±40° in the direction of diffraction. The diagonal FOV is significantly larger.
White Papers about BPGs
- Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles
- Nanoscale liquid crystal polymer Bragg polarization gratings
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Some Questions to Consider
These are typical questions we like to ask when engaging you as a customer to help best assess and understand your needs and challenges.
- What are the key issues with your current solution?
- Describe the major optical challenges you are facing. Is it low efficiency? Is there a unique polarization? a difficult phase profile to work with? or something else?
- Are there specific technology features (i.e., diffraction, polarization, retardation, wavefront, focus, opto-electronics, other) that you are interested in?
- What are the characteristics of the light source you need to work with (i.e., polarization, bandwidth, collimation, intensity, coherence)?
- What are the desired characteristics of the light at the output of the system?
- Are there any specific tests, experiments, or prototypes that would best validate a solution for your problem?
- What is the timeframe within which you need a demonstrated solution?
- Are there any unique or challenging form factor requirements? Thickness requirements? Large active area requirements?