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1. MAPbBr 3 First‐Order Distributed Feedback Laser with High Stability

   https://doi.org/10.1002/adpr.202200071  

   Chang, Cheng ; Shi, Yangwei ; Zou, Chen ; Lin, Lih Y. ( August 2022 , Advanced Photonics Research)

   A green‐emitting perovskite first‐order distributed feedback (DFB) laser based on the methylammonium lead bromide (MAPbBr₃) with high stability is demonstrated for the first time. The laser achieves stable lasing at 550 nm with a full width at half maximum of 0.4 nm. Low lasing threshold of 60 μJ cm⁻²under nanosecond pulsed excitation and 3.1 μJ cm⁻²under femtosecond pulsed excitation is observed, showing a much lower lasing threshold compared with the second‐order DFB cavities, which are fabricated on the same substrate. By optimizing the antisolvent treatment and encapsulating with poly(methyl methacrylate), the laser lifetime, resistance to moisture, lasing threshold, and intensity are significantly improved. The lasers are fabricated with a complementary metal‐oxide‐semiconductor‐compatible process, thus offer promising potential for the integrated photonic devices.

    

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2. Quartz-enhanced photoacoustic spectroscopy exploiting a fast and wideband electro-mechanical light modulator

   https://doi.org/10.1364/OE.400100  

   Zheng, Huadan ; Liu, Yihua ; Lin, Haoyang ; Kan, Ruifeng ; Dong, Lei ; Zhu, Wenguo ; Fang, Junbin ; Yu, Jianhui ; Tittel, Frank_K ; Chen, Zhe ( September 2020 , Optics Express)

   A quartz-enhanced photoacoustic spectroscopy (QEPAS) gas sensor exploiting a fast and wideband electro-mechanical light modulator was developed. The modulator was designed based on the electro-mechanical effect of a commercial quartz tuning fork (QTF). The laser beam was directed on the edge surface of the QTF prongs. The configuration of the laser beam and the QTF was optimized in detail in order to achieve a modulation efficiency of ∼100%. The L-band single wavelength laser diode and a C-band tunable continuous wave laser were used to verify the performance of the developed QTF modulator, respectively, realizing a QEPAS sensor based on amplitude modulation (AM). As proof of concept, the AM-based QEPAS sensor demonstrated a detection limit of 45 ppm for H₂O and 50 ppm for CO₂with a 1 s integration time respectively.

    

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3. Complex Swift Hohenberg equation dissipative soliton fiber laser

   https://doi.org/10.1364/PRJ.419686  

   Khanolkar, Ankita ; Zang, Yimin ; Chong, Andy ( May 2021 , Photonics Research)

   Complex Swift Hohenberg equation (CSHE) has attracted intensive research interest over the years, as it enables realistic modeling of mode-locked lasers with saturable absorbers by adding a fourth-order term to the spectral response. Many researchers have reported a variety of numerical solutions of CSHE which reveal interesting pulse patterns and structures. In this work, we have demonstrated a CSHE dissipative soliton fiber laser experimentally using a unique spectral filter with a complicated transmission profile. The behavior and performance of the laser agree qualitatively with the numerical simulations based on CSHE. Our findings bring insight into dissipative soliton dynamics and make our mode-locked laser a powerful testbed for observing dissipative solitons of CSHE, which may open a new course in ultrafast fiber laser research.

    

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4. Explicit formula for high-order sideband polarization by extreme tailoring of Feynman path integrals

   https://doi.org/10.1103/PhysRevB.107.174308  

   Wu, Qile ; Sherwin, Mark S. ( May 2023 , Physical Review B)

   High-order sideband generation (HSG), as an analog of the interband processes in high-harmonic generation (HHG) in solids, is a nonperturbative nonlinear optical phenomenon in semiconductors that are simultaneously driven by a relatively weak near-infrared (NIR) laser and a sufficiently strong terahertz (THz) field. We derive an explicit formula for sideband polarization vectors in a prototypical two-band model based on the saddle-point method. Our formula connects the sideband amplitudes with the laser-field parameters, electronic structures, and nonequilibrium dephasing rates in a highly nontrivial manner. Our results indicate the possibility of extracting information on band structures and dephasing rates from high-order sideband generation experiments with simple algebraic calculations. We also expect our approach to be useful on the quantitative understanding of the interband HHG. 

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5. Order transfer in a hybrid Raman-laser-optomechanical resonator

   https://doi.org/10.1364/OE.502262  

   Yang, Zhenning ; Zhang, Wanzhe ; Zhu, Changlong ; Wang, Zhe ; Guan, Jianqing ; Huo, Yue ; Tang, Xiaohe ; Shi, Wei ; Xia, Keyu ; Liu, Yu-xi ; et al ( October 2023 , Optics Express)

   Order is one of the most important concepts to interpret various phenomena such as the emergence of turbulence and the life-evolution process. The generation of laser can also be treated as an ordering process in which the interaction between the laser beam and the gain medium leads to the correlation between photons in the output optical field. Here, we demonstrate experimentally in a hybrid Raman-laser-optomechanical system that an ordered Raman laser can be generated from an entropy-absorption process by a chaotic optomechanical resonator. When the optomechanical resonator is chaotic or disordered enough, the Raman-laser field is in an ordered lasing mode. This can be interpreted by the entropy transfer from the Raman-laser mode to the chaotic motion mediated by optomechanics. Different order parameters, such as the box-counting dimension, the maximal Lyapunov exponent, and the Kolmogorov entropy, are introduced to quantitatively analyze this entropy transfer process, by which we can observe the order transfer between the Raman-laser mode and the optomechanical resonator. Our study presents a new mechanism of laser generation and opens up new dimensions of research such as the modulation of laser by optomechanics.

    

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