Shanghai Optical and Mechanical Institute has made progress in ultra-low threshold Rydberg state single mode polariton lasers based on symmetric engineering

Recently, the research team of Dong Hongxing and Zhang Long from the Research Center of Infrared Optical Materials of the Chinese Academy of Sciences Shanghai Institute of Optics and Precision Mechanics, in cooperation with Huazhong University of Science and Technology, reported a new mechanism for generating dynamically tunable single-mode lasers from exciton polaritons with ultra-low thresholds, The relevant research results are published in Nano Letters under the title "Rydberg State Single Mode Polarion Lasing with Ultralow Threshold via Symmetry Engineering".

The implementation of single mode nano lasers with high energy efficiency and tunable bandwidth is crucial for numerous technological applications such as all optical information processing, optical encryption, super-resolution biomedical imaging, and miniaturized intelligent display. The current strategies for obtaining single-mode lasers still have limitations.

In addition, the current control methods for emission wavelength are essentially static, and new mechanisms that can generate dynamically tunable single-mode lasers are urgently needed to be explored. Exciton polarized polaritons have both photon and exciton properties and have received widespread attention in recent years. Compared with traditional lasers, polarized polariton lasers do not require population inversion and can achieve mode tuning through quantized exciton polarized polariton states, making them an ideal platform for studying dynamically tuned ultra-low threshold lasers.

Researchers have reported the implementation of tunable single mode polarized polariton lasers from highly excited Rydberg states through symmetry engineering. By breaking the symmetry of polariton wave functions through potential traps and controlling the spatial overlap between gain regions and intrinsic modes, reversible and dynamic single mode polariton lasers can be generated from quantized polariton states. By increasing the asymmetry of the potential well, single mode lasers can be achieved even in highly excited states with a main quantum number of N=14.

In addition, due to the excellent overlap of reservoir intrinsic modes and effective spatial constraints, the laser threshold can be reduced by 6 orders of magnitude compared to traditional lasers. The mechanism elucidated by the research results does not depend on any specific material and is applicable to various polarization polariton systems, opening up a new path for the development of dynamically tunable threshold free polarization polariton lasers.

This work has been supported by projects such as the National Natural Science Foundation of China and the Shanghai Youth Top Talent Program.

Figure 1 (a) Schematic diagram of quantized polarized polariton states in a symmetric well; (b) The simulated PL spectrum corresponds to the experimental configuration shown in a; (c) Quantized polarized polariton states in asymmetric wells; (d) The simulated PL spectrum corresponds to the experimental configuration shown in c; (e) SEM images of typical ZnO microrods; (f) 1.27 radius μ Angle resolved PL images of typical ZnO microrods with m. (g) Spatial resolved PL images of polaritons confined in traps.

Figure 2 (a-d) shows the pump position dependence of spatially resolved PL images in a symmetric well. Given in each image Δ X represents the displacement of the excited laser spot from the center of the trap; (e) The spectra corresponding to the images shown in a-d; The pump position dependence of spatially resolved PL images in asymmetric wells (f-i). Δ X represents the displacement between the pumping laser spot and the opposite end face of the ground state polarization wavelet function. Pumping power: 1.25 Pth; (j) The spectra corresponding to the images shown in f-1.

Figure 3 (a-d) selectively pumped spatially resolved PL images of highly asymmetric wells at N=2, 3, 7, and 14 excited states, with a pumping power of 1.35 Pth; (e) The spatially resolved PL images of highly asymmetric wells were selectively pumped at N=2, 3, 7, and 14 excited states, with a pumping power of 1.35 Pth.

Source: OFweek