Ma Renmin's research group realizes a high-quantum efficiency topological polarization singularity laser

The research group of Professor Ma Renmin, Institute of Condensed Matter Physics and Materials Physics, Nanophotoelectronics Frontier Science Center, and State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, proposed a dual-radiation channel microcavity feedback mechanism, each radiation channel has different topological polarization characteristics, and based on this mechanism, a high-quantum efficiency topology-polarization singularity laser
is realized 。 The study, titled "Topological polarization singular lasing with highly efficient radiation channel," was published online in Nature Communications on October 30
.

High-performance lasers that realize extreme localization of light fields in different dimensions have greatly promoted the development of modern science and technology, among which miniaturized lasers that achieve localization in spatial dimensions have become the cornerstone of
modern information technology.
The design of the laser feedback chamber is the core
of achieving high-performance miniaturized lasers.

Topological polarization singularity lasers have paired radiation channels (Figure 1).

One of the paired channels is the singularity channel, which carries the topological polarization singularity and does not carry energy to the optical far field; The other is a radiation channel, whose radiation field does not carry a polarization singularity and is linearly polarized
.
The singularity channel makes this feedback mechanism have a relatively high quality factor, which is easy to achieve single-mode excitation.
The radiation channel makes this feedback mechanism have a high radiation rate and is easy to achieve high excitation quantum efficiency
.
The topographic polarization singularity laser room temperature excitation threshold realized in this work is only 1kW per square centimeter, the linewidth is 0.
14nm, the side-mode rejection ratio exceeds 36dB, and the quantum efficiency reaches 24.
5% (Figure 2).

Figure 1: Schematic diagram of a topological polarization singularity laser
.
The laser has paired radiation channels, a topological singularity channel on the left and a linearly polarization radiation channel on the right

Figure 2: Electron microscopy photographs and radiation characteristics of a topologically polarized singularity laser; (a) Electron microscope photographs; (b) band plot of momentum and wavelength-resolved spontaneous emission formation; (c) a photograph of the momentum space of the excitation, containing two singularity channels and their corresponding radiation channels; (d, e) polarization state near the topological singularity of momentum space; (f) Graph of the change of output power and line width with input power; (g) Plot of external quantum efficiency as a function of input power

Sang Yungang, a distinguished associate researcher at the School of Physics, Peking University, Lu Jingyu, a 2019 doctoral student, Ouyang Yunhao and Luan Hongyi, a 2020 doctoral student, are the co-first authors of the paper, and the authors also include 2021 undergraduate graduates of Peking University, Wu Jiahao (now a doctoral candidate at Columbia University) and Li Jiayong (now a master's student at ETH Zurich, Switzerland), and Ma Renmin as the corresponding author
of the paper.
This work has been supported
by the National Key Research and Development Program of China, the Beijing Municipal Natural Science Foundation, the National Natural Science Foundation of China, and the Tencent Foundation.