Lasing characteristics of GaInAsP-InP strained quantum-well microdisk injection lasers with diameter of 2-10 μm

We have obtained pulsed lasing operation in 2-5-μm diameter microdisk injection lasers using GaInAsP-InP compressively-strained multiple-quantum-well (MQW) wafers around room temperature. The effective cavity volume of the 2-μm-diameter device is the smallest among those for any type of electrically-pumped lasers. The threshold current of this device was as low as 0.2 mA. Cavity modes in emission spectra observed under CW conditions coincide well with theoretically predicted whispering gallery modes. Further reduction of diameter to less than 1.5 μm will realize the condition for spontaneous emission almost coupling into a single mode, which results in thresholdless lasing operation.