[Paper Review] Sub-micron single-particle perovskite plasmonic nanolasers at room temperature

Sangyeon Cho, Yi Yang+2 more|arXiv (Cornell University)|Jul 17, 2020

Plasmonic and Surface Plasmon Research15 references4 citations

TL;DR

This study demonstrates room-temperature, sub-micron single-particle plasmonic nanolasers based on cesium lead bromide perovskite (CsPbBr3) crystals deposited on polymer-coated gold substrates. By leveraging the Purcell effect, long carrier diffusivity, high spontaneous emission factor, and high group index, the authors achieve lasing at 2.3 eV with a minimum device size of 0.56 × 0.58 × 0.32 μm³—ten times smaller than their smallest photonic laser—marking a key advance in three-dimensional nanoscale laser miniaturization.

ABSTRACT

Plasmonic nanolasers have received a substantial interest for their promising applications in integrated photonics, optical sensing, and biomedical imaging. To date, a room-temperature plasmonic nanolaser, submicron in all dimensions, remains elusive in the visible regime due to high metallic losses. Here, we demonstrate single-particle lasing around 2.3 eV with full-submicron, cesium lead bromide perovskite (CsPbBr3) crystals atop polymer-coated gold substrates at room temperature. With a large number (~100) of devices in total, we systematically study the lasing action of plasmonic test and photonic control groups. The achieved smallest plasmonic laser was 0.56 micrometer x 0.58 micrometer x 0.32 micrometer in size, ten-fold smaller than that of our smallest photonic laser. Key elements to efficient plasmonic lasing are identified as enhanced optical gain by the Purcell effect, long carrier diffusivity, a large spontaneous emission factor, and a high group index. Our results shed light on three-dimensional miniaturization of plasmonic lasers.

Motivation & Objective

• To achieve room-temperature, sub-micron plasmonic nanolasers in the visible regime, where metallic losses have previously prevented such operation.
• To overcome high metallic losses in plasmonic lasers by utilizing perovskite materials with high optical gain and favorable carrier dynamics.
• To demonstrate three-dimensional miniaturization of plasmonic lasers below the diffraction limit using single-particle perovskite nanocrystals.
• To systematically compare plasmonic and photonic laser configurations to isolate the role of plasmonic enhancement in lasing efficiency.

Proposed method

• Fabrication of sub-micron CsPbBr3 perovskite nanocrystals as gain media on polymer-coated gold substrates to enable plasmonic mode confinement.
• Use of a polymer capping layer to decouple the perovskite from the metal, reducing non-radiative losses while maintaining plasmonic coupling.
• Employment of the Purcell effect to enhance spontaneous emission rate and improve laser threshold via local density of optical states modulation.
• Measurement of lasing action via photoluminescence spectroscopy under optical pumping, identifying threshold behavior and spectral narrowing.
• Systematic comparison of plasmonic test groups and photonic control groups across ~100 devices to isolate plasmonic contributions.
• Analysis of carrier diffusivity, spontaneous emission factor, and group index to identify key parameters enabling efficient lasing.

Experimental results

Research questions

• RQ1 Can sub-micron plasmonic nanolasers be achieved at room temperature in the visible spectrum despite high metallic losses?
• RQ2 What material and structural properties enable efficient lasing in perovskite-based plasmonic nanostructures?
• RQ3 How does the Purcell effect and high group index contribute to lowering the lasing threshold in these nanoscale systems?
• RQ4 What is the minimum achievable size of a functional plasmonic nanolaser using perovskite gain media?
• RQ5 How do carrier diffusivity and spontaneous emission factor influence the performance of plasmonic nanolasers?

Key findings

• The smallest observed plasmonic nanolaser achieved a size of 0.56 × 0.58 × 0.32 μm³, ten times smaller than the smallest photonic laser in the study.
• Lasing action was observed at 2.3 eV (539 nm) under optical pumping at room temperature, confirming operation in the visible regime.
• The Purcell effect significantly enhanced optical gain, reducing the lasing threshold and improving efficiency.
• Long carrier diffusivity and a high spontaneous emission factor were identified as critical for efficient population inversion and lasing.
• A high group index in the plasmonic mode contributed to mode confinement and enhanced light-matter interaction.
• Systematic comparison across ~100 devices confirmed that plasmonic structures outperformed photonic controls in threshold intensity and size scalability.