Comparison of 1.3-μm AlGaInAs/AlGaInAs Strain-Compensated Multiple-Quantum-Well Laser Diodes with/without GaInAsP and AlGaInAs Graded-Composition Layers

In this letter, we have fabricated the 1.3-μm Al_0.20Ga _0.11In_0.69As/Al_0.30Ga_0.26In _0.44As strain-compensated multiple-quantum-well laser diodes (LDs) with the GaInAsP and AlGaInAs graded-composition layers above the upper and below the lower cladding layers, respectively. This new LD structure exhibits a lower threshold current of 9 mA, a higher characteristic temperature of 80 K between 20 and 70°C, a little red-shift rate of 0.4 nm/°C and a higher relaxation frequency of 8.14 GHz at 80 mA and 20°C. Without coupling loss and damping factor, the 3 dB bandwidth of 13.1 GHz can be achieved. These characteristics are better than those LDs without the graded-composition layers.