Distributed feedback-laser diodes

Abstract

A distributed feedback-laser diode may include a substrate, a lower cladding layer having a grating on the substrate, an active layer disposed on the lower cladding layer, a first upper cladding layer disposed on the active layer, a phase-shift region extending in a first direction on the first upper cladding layer, and a ridge waveguide layer extending in a second direction crossing the first direction on the phase-shift region.

What is claimed is: 
     
         1 . A distributed feedback-laser diode comprising:
 a substrate;   a lower cladding layer having a grating on the substrate;   an active layer disposed on the lower cladding layer;   a first upper cladding layer disposed on the active layer;   a phase-shift region extending in a first direction on the first upper cladding layer;   a ridge waveguide layer extending in a second direction crossed the first direction on the phase-shift region; and   a first etch stop layer disposed under the phase-shift region and the ridge waveguide layer and on the first upper cladding layer,   wherein the phase-shift region comprises:   a second upper cladding layer disposed between the first etch stop layer and the ridge waveguide layer; and   a second etch stop layer disposed between the second upper cladding layer and the ridge waveguide layer.   
     
     
         2 . The distributed feedback-laser diode of  claim 1 , wherein the first upper cladding layer, the second upper cladding layer, and the ridge waveguide layer include at least one of InP, AlGaAs, and InGaP. 
     
     
         3 . The distributed feedback-laser diode of  claim 2 , wherein the first and second etch stop layers include InGaAs. 
     
     
         4 . The distributed feedback-laser diode of  claim 1 , wherein the ridge waveguide layer has a reverse mesa structure. 
     
     
         5 . The distributed feedback-laser diode of  claim 1 , wherein the active layer has a multiple quantum well structure. 
     
     
         6 . The distributed feedback-laser diode of  claim 1 , further comprising:
 a planarization layer surrounding the ridge waveguide layer and the phase-shift region.   
     
     
         7 . The distributed feedback-laser diode of  claim 6 , wherein the planarization layer includes polyimide or benzocyclobutene (BCB). 
     
     
         8 . The distributed feedback-laser diode of  claim 1 , further comprising:
 an electrode extending in the first direction on the ridge waveguide layer.