Optical properties of InP∕GaInP quantum-dot laser structures

Abstract

We have grown InP quantum dots with different rates and on substrates with different orientations. The growth conditions have a major influence on the form of the gain spectrum. Using a high growth rate on a 10° off (100) substrate we obtain a broad gain spectrum due to contributions from a bimodal dot size distribution whereas a sample containing mostly small dots, produced using (211)B substrates, has a narrower gain spectrum centered at a shorter wavelength of ∼700–710nm. The modal gain saturates at a magnitude significantly smaller than the modal absorption, nevertheless the measured values of modal gain are sufficient to sustain laser action, and structures grown at high growth rate on 10° off (100) substrates are capable of providing laser devices operating in the region of 750nm.