Laterally coupled distributed feedback laser fabricated with electron-beam lithography and chemically assisted ion-beam etching

Abstract

The fabrication and optical performance of laterally coupled distributed feedback (LCDFB) lasers were investigated. This device differs from a conventional DFB laser in that the grating does not extend inside the laser ridge; rather, gratings adjacent to a single ridge are used to couple to the fringing fields of the active region. This structure allows the entire laser epilayer structure to be grown in a single step, thus eliminating any regrowth steps. A recent design with 1.5 mm cavity length and chemically assisted ion-beam etching-defined ridges and gratings resulted in pulsed single-mode operation up to 36 mW at 937 nm with as-cleaved facets. The light-current characteristic of this device demonstrated a threshold current of 15 mA and a sidemode suppression ratio of greater than 30 dB. The spectral temperature sensitivity was 0.65 Å/ °C for this LCDFB. Fabrication processes and optical characterization are discussed.