  We introduce a new optical component - a rotated chirped volume Bragg grating
(r-CBG) - that spatially resolves the spectrum of a normally incident light
beam in a compact footprint and without the need for subsequent free-space
propagation or collimation. Unlike conventional chirped Bragg volume gratings
in which both the length and width of the device must be increased to increase
the bandwidth, by rotating the Bragg structure we sever the link between the
length and width of an r-CBG, leading to a significantly reduced device
footprint for the same bandwidth. We fabricate and characterize such a device
in multiple spectral windows, we study its spectral resolution, and confirm
that a pair of cascaded r-CBGs can resolve and then recombine the spectrum.
Such a device can lead to ultra-compact spectrometers and pulse modulators.

Optics