Novel method to fabricate corrugation for a λ/4-shifted distributed feedback laser using a grating photomask

Abstract
A novel method was developed to fabricate corrugation for a λ/4‐shifted distributed feedback (DFB) laser. Mechanically ruled grating patterns were transferred photolithographically to the surface of an InP substrate. The resultant λ/4‐shifted DFB laser operated in a single longitudinal mode at the Bragg wavelength.