Volume or stacked holographic diffraction gratings for wavelength division multiplexing and spectroscopy

摘要

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.