Quantum Dot Photonic Crystal Surface Emitting Lasers (PCSELs) by Epitaxial Regrowth

Semiconductor diode lasers using self-assembled InAs quantum dot (QD) active regions have been studied extensively due to their excellent device performance, such as low sensitivity to operating temperature, and record-low threshold current densities. To date QD lasers have been realized as edge emitters and vertical cavity surface emitting lasers . In this study we make use of a different laser architecture to realize vertically emitting QD lasers – the photonic crystal surface emitting laser (PCSEL). The PCSEL is able to simultaneously achieve high beam quality, high room temperature continuous wave output power, electrical injection, and with comparable fabrication complexity. The operation of the PCSEL is based on a two-dimensional photonic crystal (PC) cavity that creates feedback at a single wavelength for laterally scalable devices. The fabrication of PCSEL by epitaxial regrowth has emerged as the method of choice compared to wafer bonding and etching the PC through the clad layer. This is due to the elimination of light absorbing defects, higher device yield and better device performance.

In this present work, InAs/InGaAs/GaAs quantum-dot PCSEL was fabricated by epitaxial regrowth method using molecular beam epitaxy (MBE). The laser heterostructure with active region of three layers of InAs dots-in-well (DWELL) was optimized for 1200 nm emission wavelength design. The performance and characteristics of PCSELs were investigated and analyzed by optical pumping at room temperature.