Low Threshold 1550-nm Emitting QD Optically Pumped VCSEL

We present the first demonstration of a vertical cavity surface emitting laser (VCSEL) based on InAs quantum dots (QDs) on InP. A very high density of 10 ¹¹ cm ^-2 per QD layer, and a thin spacing layer of 15 nm are used to enhance the QD modal gain within the VCSEL cavity. Continuous wave (CW) operation is demonstrated at room temperature on optically pumped devices emitting at telecommunication wavelength (1550 nm), being the ground state transition of QDs. A very low threshold of 1.4 mW is obtained, corresponding to a value 6 times smaller than the best threshold we obtained on similar VCSEL structures integrating 1550 nm strained quantum wells. Wavelength tuning experiments have been also conducted due to a wedge cavity design. Laser emission in CW operation has been achieved on a large spectral window: from 1530 nm up to 1573 nm. A stable output polarization state with a polarization ratio exceeding 20 dB is also measured.