Bragg grating elements for optical devices
Fiber optic devices including volume Bragg grating (VBG) elements are disclosed. A fiber optic device may include one or more optical inputs, one or more VBG elements, and one or more optical receivers. Methods for manufacturing VBG elements and for controlling filter response are also disclosed. A VBG chip, and fiber optic devices using such a chip, are also provided. A VBG chip includes a monolithic glass structure onto which a plurality of VBGs have been recorded.
1. A method for manufacturing a three-dimensional holographic element having a Bragg grating holographically recorded therein, the method comprising:
placing a virgin recording wafer directly behind a recorded master hologram, wherein the virgin recording wafer is a three-dimensional bulk of optical material, and the master hologram is a Bragg grating formed on a surface of a transparent substrate; and
directing a reference beam onto the master hologram such that a replica of the master hologram is recorded in the virgin wafer to form the three-dimensional holographic element.
2. The method of claim 1 , wherein the reference beam causes a transmitted reference wave and a reconstructed object wave to be formed, and wherein the transmitted reference wave and the reconstructed object wave interfere behind the master hologram to cause the replica of the master hologram to be recorded on the virgin wafer.
3. The method of claim 1 , wherein the reference beam is directed onto the master hologram in the same fashion as during recording of the master.
4. The method of claim 1 , wherein the virgin recording wafer is a three-dimensional bulk of sensitized silica glass.
5. The method of claim 1 , wherein the master hologram is formed on a bulk of photosensitive glass.
6. The method of claim 1 , wherein the master hologram is formed on a bulk of photorefractive crystal.
7. The method of claim 1 , wherein the master hologram is formed on a bulk of dichromated gelatin.
8. The method of claim 1 , wherein the master hologram is formed on a bulk of polymer.
9. The method of claim 1 , wherein the replica of the master hologram is recorded through a first side of the three-dimensional bulk, and is adapted to be read from a second side of the three-dimensional bulk that is different from the first side.