Elimination of Bimodal Size in InAs/GaAs Quantum Dots for Preparation of 1.3-µm Quantum Dot Lasers.

The device characteristics of semiconductor quantum dot lasers have been improved with progress in active layer structures. Self-assembly formed InAs quantum dots grown on GaAs had been intensively promoted in order to achieve quantum dot lasers with superior device performances. In the process of growing high-density InAs/GaAs quantum dots, bimodal size occurs due to large mismatch and other factors. The bimodal size in the InAs/GaAs quantum dot system is eliminated by the method of high-temperature annealing and optimized the in situ annealing temperature. The annealing temperature is taken as the key optimization parameters, and the optimal annealing temperature of 680 °C was obtained. In this process, quantum dot growth temperature, InAs deposition, and arsenic (As) pressure are optimized to improve quantum dot quality and emission wavelength. A 1.3-µm high-performance F-P quantum dot laser with a threshold current density of 110 A/cm2 was demonstrated.

Bright Single-Photon Source at 1.3 µm Based on InAs Bilayer Quantum Dot in Micropillar.

A pronounced high count rate of single-photon emission at the wavelength of 1.3 µm that is capable of fiber-based quantum communication from InAs/GaAs bilayer quantum dots coupled with a micropillar (diameter ~3 µm) cavity of distributed Bragg reflectors was investigated, whose photon extraction efficiency has achieved 3.3%. Cavity mode and Purcell enhancement have been observed clearly in microphotoluminescence spectra. At the detection end of Hanbury-Brown and Twiss setup, the two avalanched single-photon counting modules record a total count rate of ~62,000/s; the time coincidence counting measurement demonstrates single-photon emission, with the multi-photon emission possibility, i.e., g 2(0), of only 0.14.

Telecommunication Wavelength-Band Single-Photon Emission from Single Large InAs Quantum Dots Nucleated on Low-Density Seed Quantum Dots.

Single-photon emission in the telecommunication wavelength band is realized with self-assembled strain-coupled bilayer InAs quantum dots (QDs) embedded in a planar microcavity on GaAs substrate. Low-density large QDs in the upper layer active for ~1.3 µm emission are fabricated by precisely controlling the indium deposition amount and applying a gradient indium flux in both QD layers. Time-resolved photoluminescence (PL) intensity suggested that the radiative lifetime of their exciton emission is 1.5~1.6 ns. The second-order correlation function of g (2)(0) < 0.5 which demonstrates a pure single-photon emission.