Perovskite Lasers: The Future of Laser Technology?

Inorganic perovskite materials have been found to be easy to prepare and process, making them suitable for creating lasers, according to research conducted at Pusan National University.

The specific perovskite material of interest is CsPbBr3, which needed to be formed into "nano-sheets" within a unique structure developed by the Pusan team in order to achieve sufficient gain for lasing.

Although lasing was not achieved in this research project, the main objective was to characterize these nano-sheets in terms of gain, temperature, and other parameters to gather data that can be used in the design of future lasers.

The university stated, "The team achieved enhanced signal amplification in nanosheets with a unique waveguide pattern, which enhanced both gain and thermal stability. These advancements carry wide-ranging implications for laser, sensor, and solar cell applications, and can potentially influence areas like environmental monitoring, industrial processes, and healthcare."

Under the right conditions, CsPbBr3 spontaneously forms atom-thick squares measuring around 150nm across from a solution. Another form of this material, known as quantum dots, can also form spontaneously, but so far, they have not provided sufficient gain for lasing.

Using micro-imprint lithography, the Pusan team created a waveguide consisting of a series of long parallel channels that are 20μm wide, 20μm deep, and separated by 20μm thick walls. This waveguide was formed in a polyurethane-acrylate substrate.

The channels were then filled with the CsPbBr3 precursor solution and carefully wiped with a blade multiple times to ensure an equal dosage in each channel. After drying, a multi-crystal nano-sheet was left at the bottom of each channel, ready for optical analysis.

The university stated, "The Perovskite nanosheets possess characteristics that make them valuable for various applications. Their achievement overcomes the shortcomings of CsPbBr3 quantum dots, whose gain is inherently limited due to the short decay time for population inversion."

As part of the results, the researchers have introduced a novel metric called the "gain contour," which depicts the relationship between gain, spectral energy, and optical stripe length. This metric is very convenient for analyzing local gain variation, according to the university.

The researchers also measured the excitation and temperature dependence of the gain contour, which quantified the increase in nano-sheet gain and thermal stability due to the polyurethane-acrylate waveguide.

Pusan National University collaborated with the University of Oxford on this research, and the results have been published in the Journal: Light: Science & Applications under the title "Gain enhancement of perovskite nanosheets by a patterned waveguide: excitation and temperature dependence of gain saturation."