Effect of InGaAsP intermediate layer in 1.3 (mu)m AIGalnAs strain-compensated multiple quantum well laser diodes

The effect is investigated of introducing a linearly graded-index separate-confinementheterostructure InGaAsP intermediate layer between the InGaAs cap layer and the lnP cladding layer to improve the characteristics of 1.3(mu)rn AIGalnAs strain-compensated multiple-quantumwell laser diodes (LDs). With the InGaAsP intermediate layer, 3 (mu)m-ridge-strip LDs without facet coating under CW operation exhibit a threshold current of 16mA, a resistance of 5.8(ohm). a characteristic temperature of 75 K in the range 20-70(degree)C and 41 K at 70-100(degree)C. a differential quantum efficiency of 50% and a low slope efficiency drop of -1.3 dB between 20 and 70(degree)C. These characteristics are better than those of LDs without the InGaAsP intermediate layer. A wavelength swing of 0.48 nm/(degree)C for LDs operated at 50 mA is achieved.