Simultaneous Dual‐Color Amplified Spontaneous Emission and Lasing from Colloidal Quantum Well Gain Media in their Own Layered Waveguide and Cavity

Abstract

Micro/nanoscale semiconductor multicolor lasers offer great potential for enhanced‐performance photonic circuits. Colloidal quantum wells (CQWs) are excellent candidates as active materials for these platforms owing to their superior properties including suppressed Auger recombination and large absorption cross‐section. In this work, multicolor optical gain and lasing from the heterostructures of CQWs as the gain media in their own all‐solution processed optical cavity are proposed and demonstrated for the first time. Here, using a simple waveguide slab consisting of the thin films of green‐emitting CdSeS/Cd0.1Zn0.9S core/hot‐injection‐shell grown CQWs and red‐emitting CdSe/CdS@CdZnS core/crown@shell CQWs, a transparent low refractive index colloidal spacing layer of silica nanoparticles (NPs) is devised that critically suppresses otherwise detrimental nonradiative energy transfer between the green and red‐emitting CQWs. This multilayer configuration is key to enabling simultaneous amplified spontaneous emission behavior in two colors with low threshold levels. This layered architecture is further adapted to a whispering‐gallery‐mode cavity by fabricating a microdisk pattern directly out of these CQWs‐NPs‐CQWs colloids. The resulting device exhibits dual‐color multimode lasing both at 569 and 648 nm at the same time. This unique multicolor lasing layered architecture holds great promise for on‐chip photonic applications such as dual‐color biological imaging.

Orientation‐Dependent Photoconductivity of Quasi‐2D Nanocrystal Self‐Assemblies: Face‐Down, Edge‐Up Versus Randomly Oriented Quantum Wells

“…[ 1,2 ] These superior features are a direct consequence of the NPL's strong quantum confinement along the vertical and atomically precise thickness, allowing them to have an ultra‐narrow light emission, large absorption cross‐section, and giant oscillator strength with their extended lateral size. [ 3,4 ] These unique properties enable such quasi‐2D NPLs to favorable building blocks of future optoelectronic and electronic devices including light‐emitting diodes, [ 5–8 ] lasers, [ 9,10 ] photovoltaics, [ 11,12 ] photodetectors, [ 13,14 ] and transistors. [ 15,16 ] So far, the main focus of the NPL‐based devices is directed toward photoemission applications due to their superior emissive properties, while very few studies have explored the diverse electrical applications thus far.…”