The influence of technological parameters on spectral properties of double-heterostructure superluminescent diodes

Linewidth and emission maximum of AIGaAs–GaAs double–heterostructure (DH) superluminescent diodes (SLDs) have been measured for current densities up to 5 kA/cm², Active diode length, thickness of the active region and aluminium content of the confining layers have been varied. Thereby it has been found that emission wavelength and spectral linewidth saturate at increasing current density to minimum values determined by these technological parameters. The minimum linewidth achieved by diodes with active length greater than 250 µm is nearly proportional to the reciprocal square root of diode length. Spectral width of 7 nm at 2.5 kA/cm² has been achieved with active diode length of 1.5 mm.