CASCADE SELF-INDUCED HOLOGRAPHY - A NEW GRATING FABRICATION TECHNOLOGY FOR DFB DBR LASERS AND WDM LASER ARRAYS/

A method of fabricating submicron gratings for optoelectronic devices from a glass mask was proposed and demonstrated, The glass mask has gr atings on both sides with a period of at least four times the final fe ature size, By introducing an offset to the grating periods on the mas k, one can achieve multiple-period gratings with a very fine period sp acing for advanced wavelength-division multiplexing (WDM) devices. In this paper, we demonstrated 0.5-mu m second-order gratings for 1.55-mu m DFB lasers and gratings with a 6-Angstrom period difference for a f our-channel WDM laser array using only optical sources. The Moire patt ern caused by the spatial frequency beating was also observed and disc ussed, The Moire pattern could serve as an effective tool to measuring wavelength channel spacing between devices with an unprecedented (0.1 Angstrom) resolution.