Synchrotron Radiation Lithography for DFB Laser Gratings

Abstract
The synchrotron radiation lithography process of grating fabrication for distributed feedback (DFB) laser diodes is described. By finely controlling the field size in electron beam writing of the X-ray mask, the grating period can be arbitrarily varied with an accuracy of less than 0.1 nm . Gratings of 0.24-µm period with a λ/4 shift are formed in the Ta absorber X-ray mask, and transferred to the laser substrate by SR exposure. This process is successfully applied to the fabrication of 20-wave-length DFB-LD arrays.