Single crystal diamonds with strong NV− luminescence were prepared by high-pressure high-temperature method and followed by electron irradiation and annealing process. The stimulated emission and gain characteristics of NV− diamond in femtosecond time scale are also studied using the transient absorption technique. Stimulated emission was observed at 660–800 nm, with an optical gain displayed in the range of 680–725 nm. Further test revealed that the optical gain lifetime is 3.5 ns and the gain coefficient is 0.16 cm−1, demonstrating the potential realization of color center lasers.

Transient (computer programming)

Center (category theory)

10.1080/26941112.2024.2449373

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Observation of transition from superfluorescence to polariton condensation in CsPbBr3 quantum dots film

Light Science & Applications (2024)

Danqun Mao Linqi Chen Zheng Sun Min Zhang Zhe-Yu Shi

Abstract The superfluorescence effect has received extensive attention due to the many-body physics of quantum correlation in dipole gas and the optical applications of ultrafast bright radiation field based on the cooperative quantum state. Here, we demonstrate not only to observe the superfluorescence effect but also to control the cooperative state of the excitons ensemble by externally applying a regulatory dimension of coupling light fields. A new quasi-particle called cooperative exciton-polariton is revealed in a light-matter hybrid structure of a perovskite quantum dot thin film spin-coated on a Distributed Bragg Reflector. Above the nonlinear threshold, polaritonic condensation occurs at a nonzero momentum state on the lower polariton branch owning to the vital role of the synchronized excitons. The phase transition from superfluorescence to polariton condensation exhibits typical signatures of a decrease of the linewidth, an increase of the macroscopic coherence as well as an accelerated radiation decay rate. These findings are promising for opening new potential applications for super-brightness and unconventional coherent light sources and could enable the exploitation of cooperative effects for quantum optics.

10.1038/s41377-024-01378-5

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Correction to: Arbitrary topological charge vortex beams from carbon dots random lasers

Rare Metals (2024)

Xiangdong Wang Xiao-Bo Mi Jiu-Ru He Fengying Ma Junqiao Wang

10.1007/s12598-024-02885-5

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Arbitrary topological charge vortex beams from carbon dots random lasers

Rare Metals (2024)

Xiangdong Wang Xiao-Bo Mi Jiu-Ru He Fengying Ma Junqiao Wang

Carbon fibers

10.1007/s12598-024-02660-6

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High-efficiency asymmetric diffraction based on PT-antisymmetry in quantum dot molecules

Chinese Physics B (2021)

Guangling Cheng Yongsheng Hu Wenxue Zhong Aixi Chen

Abstract We present preparation of asymmetric grating with higher diffraction efficiency in quantum dot molecules by combining the tunneling effect and parity-time antisymmetry. In the presence of tunneling between two quantum dots, the system exhibits the striking PT antisymmetry via spatially modulating the driving field and the detuning with respect to the driven transition. For this reason, the asymmetric grating could be achieved. The results show that the diffraction efficiency can be adjustable via changing the driving intensity, detuning, tunneling strength, and interaction length, and then the high-order diffraction can be reached. The scheme provides a feasible way to obtain the direction-controlled diffraction grating, which can be helpful for optical information processing and realization of controllable optical self-image.

Antisymmetry

Realization (probability)

Diffraction efficiency

10.1088/1674-1056/ac0422

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Eye-safe intra-cavity diamond cascaded Raman laser with high peak-power and narrow linewidth

Chinese Optics Letters (2024)

X.-B. Mi Chaonan Lin Yongsheng Hu Houjie Ma Jiuru He

The 1.4–1.8 µm eye-safe lasers have been widely used in the fields of laser medicine and laser detection and ranging. The diamond Raman lasers are capable of delivering excellent characteristics, such as good beam quality concomitantly with high output power. The intra-cavity diamond Raman lasers have the advantages of compactness and low Raman thresholds compared to the external-cavity Raman lasers. However, to date, the intra-cavity diamond cascaded Raman lasers in the spectral region of the eye-safe laser have an output power of only a few hundred milliwatts. A 1485 nm Nd:YVO4/diamond intra-cavity cascaded Raman laser is reported in this paper. The mode matching and stability of the cavity were optimally designed by a V-shaped folded cavity, which yielded an average output power of up to 2.2 W at a pulse repetition frequency of 50 kHz with a diode to second-Stokes conversion efficiency of 8.1%. Meanwhile, the pulse width of the second-Stokes laser was drastically reduced from 60 ns of the fundamental laser to 1.1 ns, which resulted in a high peak power of 40 kW. The device also exhibited single longitudinal mode with a narrow spectral width of < 0.02 nm.

Laser linewidth

Raman laser

10.3788/col202422.041402

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