In the field of long-wave infrared (LWIR) thermal imaging, vital for applications such as military surveillance and medical diagnostics, metalenses show immense potential for compact, lightweight, and low-power optical systems. However, to date, the development of LWIR broadband achromatic metalenses with dynamic tunable focus, which are suitable for both coaxial and off-axis applications, remains a largely unexplored area. Herein, we have developed an extensive database of broadband achromatic all-As2Se3 microstructure units for the LWIR range. Utilizing this database with the Particle Swarm Optimization (PSO) algorithm, we have designed and demonstrated LWIR broadband achromatic metalenses capable of coaxial and off-axis focusing with three dynamic tunable states. This research may have potential applications for the design of compact, high-performance optical devices, including those with extreme depth-of-field and wide-angle imaging capabilities.

Lasers from ¹I₆ to ³F₄ transitions were first demonstrated in a Pr³⁺:YLF crystal by inserting a birefringent filter. Output powers up to 2.44 W, 2.10 W, 2.01 W and 2.42 W were obtained at 691.7 nm, 701.4 nm, 705.0 nm and 708.7 nm. Their slope efficiencies were 19.8%, 16.5%, 15.8% and 19.4%, respectively. The Mx² and My² factors were measured to be 2.29 and 2.03 at 691.7 nm, 2.23 and 1.86 at 701.4 nm, 2.31 and 2.08 at 705.0 nm, and 2.41 and 2.04 at 708.7 nm, with corresponding power fluctuations of less than 5.3%, 5.6%, 5.8%, and 2.9%.

In this work, we proposed and experimentally demonstrated a novel probabilistic shaping (PS) 64QAM-OFDM with low-density parity-check (LDPC)-coded modulation in a W-band RoF system using envelope detection. The proposed PS scheme has the advantages of no complex multiplication and division operations and low hardware implementation complexity. In our experiments, the TS-BWDM-based PS-64QAM DMT signals with a rate of 28.3-Gb/s transmission over 4-m wireless + 45-km SSMF transmission can be achieved. The system performance is investigated under one LDPC code rates (3/4) and two PS parameter values (k=3 and 9). The experimental results show that the receiver power sensitivity and the system fiber nonlinear effect tolerance can be significantly improved compared with uniformly-distributed signals.

In this study, an innovative technique is introduced to significantly enhance the sensitivity of electronic speckle pattern interferometry (ESPI) for the dynamic assessment of specular (mirrorlike) object deformations. By utilizing a common-path illumination strategy, wherein illumination and observation beams are precisely aligned, this method effectively doubles the optical path difference, leading to a twofold increase in measurement sensitivity. In addition, this method mitigates the effects of speckle noise on the measurement of minor deformations, expanding the applications of ESPI. Theoretical and experimental evaluations corroborate the efficacy of this approach.

We report on a compact, high efficiency mid-infrared continuous-wave (CW) Fe:ZnSe laser pumped by a 2.9 μm fiber laser under liquid nitrogen cooling. A maximum output power of 5.5 W and a slope efficiency of up to 66.3% with respect to the launched pump power were obtained. The overall optical-to-optical (OTO) conversion efficiency, calculated from the output of 2.9 μm fiber laser to the 4-µm laser, was as high as ~54.5%. The OTO efficiency and the slope efficiency are, to the best of our knowledge, the highest in ever reported Fe:ZnSe lasers. A rate-equation-based numerical model of CW operation was established, and the simulation agreed well with the experiment, identifying the routes used in the experiment for such high efficiency.

In this manuscript, an auto-focusing method in optical scanning holography (OSH) system is proposed. By introducing Lissajous scanning into multiple signal classification (MUSIC) method in time reversal (TR) OSH, the axial locations of the targets can be retrieved with better resolution. The feasibility of this method is confirmed by simulation as well as experiment.

We demonstrated an actively acousto-optic Q-switched pulsed laser based on Pr:YLF at 604 nm. A 604 nm continuous-wave (CW) laser with maximum output power of 3.84 W was achieved for the first time. The Q-switched laser with a maximum average output power of 0.384 W, a narrowest pulse duration of 44.5 ns, a maximum single pulse energy of ~64.1 μJ, and a maximum peak power of ~1.44 kW were obtained at a repetition rate of 6 kHz. To the best of our knowledge, this was the first report of such narrow pulse duration, high power and high energy Q-switched pulsed laser at 604 nm. The beam quality M2 x and M2 y factors were measured to be 2.87 and 2.40 respectively. The results shown that acousto-optic Q-switching was a promising method to obtain pulsed lasers.

Determining the trap density in the absorbing layer thin film of perovskite solar cells is a important task, as it exerts a direct influence on the efficiency of the devices. Here, we proposed the utilization of time-resolved photoluminescence (TRPL) as a non-destruction method to evaluate trap density. A model has been formulated to investigate carrier recombination and transition processes in perovskite materials, subsequently employed for numerical computations and successfully fitted to TRPL signals. Moreover, a genetic algorithm was implemented to optimize the relevant parameters. Finally, statistical methodologies were applied to obtain the parameters associated with the trap states inherent to the material. This comprehensive approach facilitates the successful determination of trap densities across varying samples, enabling clear differentiation.

We establish a quantum theory of computational ghost imaging and propose quantum projection imaging where object information can be reconstructed by quantum statistical correlation between a certain photon number of bucket signal and DMD random patterns. The reconstructed image can be negative or positive depending on the chosen photon number. In particular, the vacuum state (zero-number) projection produces a negative image with better visibility and contrast-to-noise ratio. The experimental results of quantum projection imaging agree well with theoretical simulations and show that, under the same measurement condition, vacuum projection imaging is superior to conventional and fast first-photon ghost imaging in low-light illumination.

The optoelectronic performance of quantum cascade detectors (QCDs) is highly sensitive to the design of the energy level structure, leading to the inability of a single structure to achieve broad wavelength tuning. To address this issue, we propose and demonstrate a modular concept for very long wave infrared (VLWIR) QCDs based on a miniband diagonal transition scheme. The modular design makes the wavelength tuning only need to be adjusted for the absorption quantum well module rather than for the whole active region. Theoretical simulation shows that the wavelength tuning range is 39.6 meV (~ 14-30 μm). To prove the feasibility of the scheme, three samples with different absorption well widths were fabricated and characterized. At 10 K, the response wavelengths of the three QCDs are 14, 16, and 18 μm, respectively, corresponding to responsivities and detectivities exceeding 2 mA/W and 1×10¹⁰Jones.