GENERATION OF MULTIPLE-PITCH GRATINGS IN WDM DEVICES BY USING A SINGLE COMPUTER-GENERATED PHASE MASK

Use of a single computer-generated phase mask (CGPM) for monolithic fa brication of submicronmeter multiple-pitch gratings is proposed. The C GPM is a computer-generated Fourier hologram generating multiple diffr acted beams with equal intensity from a single incident beam, The subm icronmeter grating periods differing by as little as a few angstroms a re estimated with basis of the multiple diffraction angles, As a resul t of preliminary experiment, an array of nine gratings has been achiev ed by using a CGPM with 2-mu m minimum feature size, Limit of the CGPM period due to increase in wavelength spacing of WDM devices is also d iscussed.