Microchip laser converter based on InGaN laser diode and (Zn)CdSe quantum dot heterostructure

A high-efficiency microchip violet–green laser converter based on a molecular-beam epitaxy grown green-emitting (Zn)CdSe quantum dot (QD) II–VI laser heterostructure, optically pumped by emission of a cheap violet InGaN laser diode (LD) was demonstrated. The active region of the II–VI laser heterostructure consisted of three electronically coupled (Zn)CdSe QD sheets in a single ZnSe quantum well (QW) placed asymmetrically inside a graded-index ZnMgSSe/ZnSe superlattice optical waveguide. The cavity length of the cleaved-facet II–VI laser was 130 μm which is a nearly optimal value for minimizing the excitation power. InGaN LD radiation was focused into a narrow stripe on the surface of the II–VI laser by a microlens optical system. The converter showed laser emission at 541 nm with threshold excitation power of ∼0.5 W. The maximal output pulse power and conversion efficiency of 1.5 W and ∼15%, respectively, were achieved.