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A special form of a blazed grating is the echelle grating. It is characterized by particularly large blaze angle (>45°). Therefore, the light hits the short legs of the triangular grating lines instead of the long legs. Echelle gratings are mostly manufactured with larger line spacing but are optimized for higher diffraction orders.
A grating can be defined by six parameters: Spatial frequency is the number of cycles occupying a particular distance (e.g. 10 line pairs per millimeter). The period of the grating is the inverse of the spatial frequency, measured in distance (e.g. 0.1 mm). Duty Cycle is the relative thickness of high and low lines. The duty cycle is the ratio ...
EMPy ("Electromagnetic Python") software. motofit is a program for analysing neutron and X-ray reflectometry data. OpenFilters is a program for designing optical filters. Py_matrix is an open source Python code that implements the transfer-matrix method for multilayers with arbitrary dielectric tensors. It was especially created for plasmonic ...
Typically the grating period is the same size as the Bragg wavelength, as shown above. For a grating that reflects at 1,500 nm, the grating period is 500 nm, using a refractive index of 1.5. Longer periods can be used to achieve much broader responses than are possible with a standard FBG. These gratings are called long-period fiber grating ...
The Gerchberg-Saxton algorithm. FT is Fourier transform. The Gerchberg–Saxton (GS) algorithm is an iterative phase retrieval algorithm for retrieving the phase of a complex-valued wavefront from two intensity measurements acquired in two different planes. [1]
The free spectral range of a diffraction grating is the largest wavelength range for a given order that does not overlap the same range in an adjacent order. If the ( m + 1)-th order of λ {\displaystyle \lambda } and m -th order of ( λ + Δ λ ) {\displaystyle (\lambda +\Delta \lambda )} lie at the same angle, then
A software controlled binary liquid crystal stack, individually tilts each optical channel and a second grating (or a second pass of the first grating) is used to spectrally recombine the beams. The offsets created by the liquid crystal stack cause the resulting spectrally recombined beams to be spatially offset, and hence to focus, through a ...
An example of guided-mode resonance is a grating coupler, which is a region on top of or below a waveguide where there is a grating. Off-resonance light incident on the grating behaves almost the same as it would if it was incident in an area where there is no grating. Waveguides are usually made of dielectric and are transparent. For specific ...