| Popis: |
Compact and efficient spectrometers are of great interest for biological and environmental sensing. In this paper, we describe a new class of spectrometers that work based on diffractive properties of spherical beam volume holograms (SBVHs) and cylindrical beam volume holograms (CBVHs). The hologram in these spectrometers acts as a spectral diversity filter (SDF) that maps different input wavelengths onto different locations in the output plane. The main properties of these holographic SDFs and new techniques for removing the ambiguity between incident wavelength (or the input channel) and incident angle (or the input spatial mode) are discussed. By using CBVHs, we show that the spectral mapping of the input beam can be obtained in one direction and the beam can be independently modified in the perpendicular direction. Using this unique property, we demonstrate a spectral wrapping technique to considerably increase the operation spectral range of spectrometers, without sacrificing their resolution. Finally, it is also shown that by combining CBVHs with a Fabry-Perot interferometer, a true two-dimensional spatial-spectral mapping can be formed, and an ultra-high resolution of 0.2 nm with large spectral bandwidth is demonstrated for this tandem spectrometer. |
