Volume or stacked holographic diffraction gratings for wavelength division multiplexing and spectroscopy
First Claim
1. An optical coupling device for use with a beam of electromagnetic radiation comprising two, or more than two composite signals, said device comprising a volume diffraction grating having a substrate, and one, or more than one optically active layer attached to said substrate, said one, or more than one optically active layer separating and dispersing said two, or more than two composite signals, characterized in that each one of said one, or more than one optically active layer comprises two, or more than two intersecting diffraction structures, each one of said two, or more than two intersecting diffraction structures having a specific periodic modulation of refractive index.
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Abstract
A volume diffraction grating having a substrate and an optically active layer has a structure formed in the optically active layer. The structure is operational to diffract optical signals in two selected spectral bands. The grating may be formed in a high dispersion embodiment suitable for separating individual signals from composite signals of both spectral bands. Alternatively, the grating may be formed in a low dispersion version which can separate the composite signals from each other. In another embodiment, a second structure is formed in the optically active layer. Each of the structures is configured to be operational in one of the spectral bands, allowing signals in each band to be diffracted independently of one another. In another embodiment, the structure(s) may have a curved profile allowing the diffracted beams to be shaped or focused without the need for external lenses.
71 Citations
18 Claims
- 1. An optical coupling device for use with a beam of electromagnetic radiation comprising two, or more than two composite signals, said device comprising a volume diffraction grating having a substrate, and one, or more than one optically active layer attached to said substrate, said one, or more than one optically active layer separating and dispersing said two, or more than two composite signals, characterized in that each one of said one, or more than one optically active layer comprises two, or more than two intersecting diffraction structures, each one of said two, or more than two intersecting diffraction structures having a specific periodic modulation of refractive index.
Specification