Far-field patterns of Quantum Well, Quantum Dash, and Quantum Dot Laser Diodes

We perform measurements of far field pattern of various quantum-confined heterostructures namely quantum well (QW), quantum dash (Qdash), and quantum dot (Qdot) lasers to study the effect of different active gain mediums of semiconductor lasers on the optical beam quality and coupling efficiency. The beam pattern profile of the Qdash laser is similar to that of the QW laser (FWHM ~ 20deg) while Qdot laser shows smaller divergence (FWHM ~ 5deg) and retain its intensity profile of single lobe Gaussian-shape at current injection up to two and half times threshold current.