Ultra Thick Gratings (UTG)
 
Ultra Thick Gratings (UTG) represents a new grating platform technology
capable of many photonic applications.  Our UTG technology is based on a
proprietary polymer composite that has a refractive index modulation within the
volume of the material.  The proprietary polymer composites are physically and
chemically very stable, resulting in a robust grating structure subjected to typical
telecom and military operating temperatures.  Unlike conventional phase
gratings, ultra thick gratings can be made with thickness from 3 microns to 3
mm in excellent optical transparency.  UTG can be polarization insensitive
suitable for many fiber-optic applications.  UTG exhibits high diffraction
efficiency, low wavefront distortion, low optical scattering.  UTG, packaged
between two integrated glass plates, is extremely durable and easy to handle.

Typical Grating Specifications
The advantages of UTG are obvious:
.    UTG hasa higher peak diffraction efficiency achievable ( >95% ),       
•    UTG can have a very large thickness up to 3 mm,
•    UTG is protected and can be cleaned,
•    UTG is lack of ghost and scattered light,
•    UTG can be tuned to peak the diffraction efficiency at a desired wavelength,
•    UTG can be designed to work in transmission or reflection,
•    UTG can be recorded with aberration compensation,
•    UTG can be produced in large dimension.

UTG diffraction efficiency can be theoretically modelled by both the rigorous
coupled wave analysis or modal analysis. These theories take multi-order
diffraction into account. Their formalisms require computation since no analytic
solution can be found for useful configurations. However, in most cases, first
order efficiency can be estimated by the Kogelnik's two-wave coupled analysis,
which is simplified by approximations.
Following Simulation Shows Typical Performance Difference
Between Ultra Thick Gratings and Conventional Gratings:
Operating Wavelength
350 nm ~ 4000 nm
Diffraction Efficiency
1% ~ 99.9%
Diffraction Angle
1 ~ 89 Degree
Incident Angle
0 ~ 89 Degree
Grating Thickness
1 ~ 5000 microns