Far-field diffraction characteristics of a Gaussian pulse incident on a sinusoidal phase grating

Data Transmission Scheme with Spectral Switches of a Tilting Circular Mirror in Far Field

“…( 1) is usually used for a monochromatic incident field, U 0 ðp 0 ; tÞ ¼ U 0 ðp 0 ; !Þe À j!t , with a single frequency ! and the constant complex amplitude U 0 ðp 0 ; !Þ; however, it is also applicable for a broad-band pulse or a polychromatic field, [1][2][3][4][5][6][7][8][9][10] which can be superposed with monochromatic fields via the Fourier integral. 15) In cylindrical coordinate, the Fourier transform is called Fourier-Hankel transform which is defined as 16) FHðgð 0 ; 0 ÞÞ ¼…”

“…The spectral switch has been utilized in information encoding and transmission in free space. 2,9,10) It is found that the aperture mechanism 3) is easier to perform the transmitting task than the light source mechanism, 6) which the former controls the geometrical properties of the aperture and the latter modulates rms bandwidth or spatial coherence of the light source. In this work the easier aperture mechanism is also used for the data transmitting while the properties of incident light source do not need any changes.…”

“…Spectral anomalies, [1][2][3][4][5][6][7][8][9][10][11][12][13] which are caused by the diffraction of some apertures or devices for a polychromatic light source (or broad band pulses) lately has gained more interests for their different applications such as lattice spectroscopy 1) or spatial-coherence spectroscopy. 4) Another important application is to transmit the digital information in free space with the spectral switches 2,3,[5][6][7] which has been verified experimentally.…”

“…It is known that the singularities are only the sufficient condition for the spectral switch and that the necessary condition is the oscillatory behavior of the modifier function. 3) However, most of the previous methods, [5][6][7][8][9][10] except ref. 2, provided only numerical results and the transmitting directions were unpredictable; thus their practical usages in data transmission are seriously limited.…”

“…Also the control mechanism is easy to perform by just changing the tilting angle of the mirror, in stead of by changing properties of the light source (e.g., spatial coherence or spectral bandwidth). 6,9,10)…”