We experimentally explore the generation of pre-pulses by post-pulses, created through internal reflection in the optical components, by the nonlinear process associated with the B-integral in the laser chain of the petawatt (PW) facility J-KAREN-P. At a large time delay between the main and the post-pulses, we have found that the pre-pulses are not generated from their counterpart post-pulses at an identical time difference before the main pulse, and the temporal shapes of the pre-pulses are greatly distorted asymmetrically. We have also observed that the peak intensities of the pre-pulses are drastically suppressed compared to the expected value at a small time delay. We briefly describe the origins of the pre-pulses generated by the post-pulses and demonstrate the removal of the pre-pulses by switching to optical components with a small wedge angle at our PW laser facility.We report on a new, to the best of our knowledge, sensing concept based on Bloch surface waves (BSWs) and wavelength interrogation that utilizes the interference of $ s $s- and $ p $p-polarized waves from a one-dimensional photonic crystal (1DPhC), represented by a multilayer structure comprising a glass substrate and four bilayers of $ \rm TiO_2/\rm SiO_2 $TiO2/SiO2 with a termination layer of $ \rm TiO_2 $TiO2.  https://www.selleckchem.com/products/epoxomicin-bu-4061t.html  We show that when a standard approach based on measurement of the reflectance of a $ p $p- or $ s $s-polarized wave in the Kretschmann configuration fails to confirm the excitation of the BSW, a new approach is successful. We demonstrate that the BSW excitation shows up as a dip with maximum depth, and resonance thus obtained is comparable in magnitude with resonance commonly exhibited by surface plasmon resonance (SPR). The new sensing concept is verified experimentally for ethanol vapors. The BSW resonances are resolved within two band gaps of the 1DPhC with sensitivities of 3272 nm/RIU and 1403 nm/RIU, and figures of merit of $ 43.7 \;\rm RIU^ - 1 $43.7RIU-1 and $ 173.2 \;\rm RIU^ - 1 $173.2RIU-1, respectively. This research, to the best of the authors' knowledge, is the first demonstration of a new SPR-like response that can be utilized in a wide range of sensing applications.For the first time, to the best of our knowledge, laser cooling is reported in a silica optical fiber. The fiber has a 21-µm diameter core doped with 2.06 wt.% $\rm Yb^3 + $Yb3+ and co-doped with $\rm Al_2\rm O_3$Al2O3 and $\rm F^ - $F- to increase the critical quenching concentration by a factor of 16 over the largest reported values for the Yb-doped silica. Using a custom slow-light fiber Bragg grating sensor, temperature changes up to $ - 50\;\rm mK$-50mK were measured with 0.33 W/m of absorbed pump power per unit length at 1040 nm. The measured dependencies of the temperature change on the pump power and the pump wavelength are in excellent agreement with predictions from an existing model, and they reflect the fiber's groundbreaking quality for the radiation-balanced fiber lasers.We demonstrate silicon-based $p \text- n \text- p$p-n-p floating-base GeSn heterojunction phototransistors with enhanced optical responsivity for efficient short-wave infrared (SWIR) photodetection. The narrow-bandgap GeSn active layer sandwiched between the $p \text- \rm Ge$p-Ge collector and $n \text- \rm Ge$n-Ge base effectively extends the photodetection range in the SWIR range, and the internal gain amplifies the optical response by a factor of more than three at a low driving voltage of 0.4 V compared to that of a reference GeSn $p \text- i \text- n$p-i-n photodetector (PD). We anticipate that our findings will be leveraged to realize complementary metal-oxide-semiconductor-compatible, sensitive, low driving voltage SWIR PDs in a wide range of applications.In this Letter, we exploit the polarization property of light to investigate the Ångström exponent describing the wavelength dependence of optical backscatter between two wavelengths. Where previous interpretation of Ångström exponent was that of a particle size indicator, the use of light polarization makes it possible to investigate the Ångström exponent dependence on the particle shape by separately retrieving the backscattering Ångström exponent of the spherical (s) and non-spherical (ns) particles contained in an atmospheric particle mixture $(p) = \s, \rm ns\$(p)=s,ns. As an output, analytical solutions of the Maxwell's equations (Lorenz-Mie theory, spheroidal model) can then be applied to investigate the Ångström exponent dependence on the particle size and complex refractive index for each assigned shape. Interestingly, lidar-retrieved vertical profiles of backscattering Ångström exponents specific to $s$s- and ns-particles can be used by the optical community to evaluate a range of involved particle sizes and complex refractive indices for both particle shapes, $s$s and ns, as we remotely demonstrate on a case study dedicated to a dust nucleation event.We experimentally investigate a fixed point of a bi-directional dual-comb ring laser and the behavior of dual-comb signals in different spectral regions. We show that the results are quite different from those obtained with traditional dual-comb spectroscopy. We explain the difference using the elastic tape formalism that we apply to a bi-directional ring laser. We also discuss how the results can aid efforts to synchronize two bi-directional laser systems to enable rapid and high-resolution multidimensional coherent spectroscopy with a compact apparatus.This publisher's note contains corrections to Opt. Lett.45, 371 (2020).OPLEDP0146-959210.1364/OL.379968.In this Letter, we propose a technique for hysteresis loop measurement based on weak measurement. By using the photonic spin Hall effect (PSHE) as a probe and combining the quantum weak measurement, the technique's noise can be suppressed greatly. A theoretical model to describe the numerical relation between the amplified shift and Kerr rotation angle is established. Through detecting the amplified shift of the PSHE based on weak measurement, we experimentally measure the hysteresis loops of Ni-Fe alloy film, iron-phthalocyanine (FePc) monolayer film, and Co/FePc double-layer film. The results show that the precision can reach about $ \sim 10^ - 6 \;\rm rad $∼10-6rad under ordinary experimental conditions, which may have an important application prospect in magneto-optic parameters measurement.