Distributed-feedback interband cascade lasers with reduced contact duty cycles

Abstract

We report the single-mode operation of mid-infrared distributed-feedback (DFB) interband cascade lasers (ICLs) with contacts that cover only a fraction of the top surface of the laser ridge. This reduces the optical loss from the metal for the GaSb-relevant device configuration in which the grating is fabricated in the top layer of the DFB laser. Continuous wave (cw) room-temperature operation in a single spectral mode is observed for contact duty cycles as small as 14% when the width of the contact is fixed at 10 μm. The reduced contact duty cycle results in a factor of 2 decrease in the threshold current. The highest slope efficiency is observed for a contact duty cycle of 33%, for which the cw single-mode output power is as high as 6.8 mW.