ESTIMATION OF CARRIER CAPTURE TIME OF QUANTUM-WELL LASERS BY SPONTANEOUS EMISSION-SPECTRA

Carrier capture time was estimated for separate confinement heterostructure single quantum-well lasers by measuring the spontaneous emission from the optical confinement layers which increases with current even above the laser threshold due to finite carrier capture time of the well. By fitting theoretical analysis to the measurement, hole capture time was found to be the dominant factor for the spontaneous emission increase, and was estimated as 0.2-0.25 ps for GaInAs/GaInAsP/InP quantum well lasers. Additional transport time of 0.1-0.2 ps across the barrier was also obtained for multiquantum well lasers. It appears that the finiteness of carrier capture time affects not only the threshold current but also the differential quantum efficiency in high power operation through the absorption loss by the carriers in the optical confinement layers.