Notes

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We report, as far as we know for the first time, on a pulsed 2.7 µm ErZBLAN fiber laser Q-switched by an electro-optic modulator. The Q-switched operation was achieved with a repetition rate range of 100 Hz-50 kHz. Pulse energy of 205.7 µJ and pulse width down to 13.1 ns, yielding a peak power of 15.7 kW, were obtained at a repetition rate of 100 Hz. The linewidth of the output spectrum was as narrow as 0.4 nm. The pulse width and the pulse peak power, to the best of our knowledge, are currently the shortest and the highest in the 3-µm-band Q-switched fiber lasers, respectively.By incorporating a holographically designed aperiodic photonic lattice within one of the arms of a Y-coupled Fabry-Perot quantum cascade laser architecture, it has been demonstrated that the multiband mode control exerted by the photonic lattice on emission spectra can, owing to the mutual optical coupling between the arms, be transferred to the second unpatterned arm. However, the underlying theoretical mechanism on how the lattice influences the threshold gain spectral properties of the Y architecture has, until now, remained unstudied. Here, we use the transfer matrix formalism, originally developed for studying aperiodic lattice lasers, to investigate this. A detailed threshold gain spectral study revealed that although the effects of facet feedback of the Y-coupled laser chip are present, due to the enhanced photonic density-of-states at user-specified frequencies, the aperiodic lattice has remarkable control over the Y architecture laser spectra, under the mutual optical coupling between the arms. Finally, indicated by the fringe patterns akin to double-slit interference, of the measured far-field beam profiles, phase-locked terahertz emissions from the Y architecture are demonstrated.We report a high brightness cascaded Stokes diamond Raman laser with a diffraction limited beam quality pumped by an Yd-doped fiber laser. The Raman laser operated at 1477 nm and reached an output power of 63 W with 214 W pump power in continuous-wave mode. Conversion efficiency over 30% was achieved using a single pump pass concentric cavity that was highly resonant at the first Stokes and had high outcoupling at the second Stokes (45%). Thermal limitations were investigated as well as the temporal behavior of the first and second Stokes intra-cavity power.We demonstrate a simple and power stable 1.5-10.5 µm cascaded mid-infrared 3 MHz supercontinuum fiber laser. To increase simplicity and decrease cost, the design of the fiber cascade is optimized so that no thulium amplifier is needed. Despite the simple design with no thulium amplifier, we demonstrate a high average output power of 86.6 mW. Stability measurements for seven days with 8-9 h operation daily revealed fluctuations in the average power with a standard deviation of only 0.43% and a power spectral density stability of ±0.18dBm/nm for wavelengths less then 10µm. The high-repetition-rate, robust, and cheap all-fiber design makes this source ideal for applications in spectroscopy and imaging.Pulses at 744 nm with 90 fs duration, 6 mJ energy, and a weakly divergent wavefront propagate for more than 100 m and generate a filament followed by an unprecedently long high intensity (≥1TW/cm2) light channel. Over a 20 m long sub-section of this channel, the pulse energy is transferred continuously to the infrared wing, forming spectral humps that extend up to 850 nm. From 3D+time carrier-resolved simulations of 100 m pulse propagation, we show that spectral humps indicate the formation of a train of femtosecond pulses appearing at a predictable position in the propagation path.To describe ultrashort pulse amplification in semiconductor optical amplifiers (SOAs), several models have been developed that calculate the amplified output pulse as a function of the input. Because of the many processes at play in SOAs (band filling, carrier heating, spectral hole burning, two-photon absorption, and the associated free-carrier absorption), it is challenging to predict which input is needed to generate a targeted output. In this Letter, we construct a generic inverse SOA model that calculates the required input pulse including its shape and phase to obtain a desired output. This inverse model will enable a more efficient and well-targeted design of SOA-based photonic systems, while also allowing better quality and performance control.The polarization of light, the vector nature of electromagnetic waves, is one of the fundamental parameters. Finding a direct and efficient method to measure the state of polarized light is extremely urgent for nano-optical applications. Based on Malus's law, we design an ultracompact metasurface composed of silver nanorods, which is demonstrated to directly measure the state of linear polarization by a grayscale image. Using an ultrathin metasurface, we generate grayscale images with gradient grayscale levels which are linked directly to the polarization state of the incident light. The direction of the linear polarization of incident light can be conveniently and efficiently obtained through extracting the angle of the brightest area of the grayscale image. The ultrathin metasurface operates in the broadband 750-1100 nm spectral range. It is a novel and significant method to analyze the linear polarization state of light, which provides opportunities for various applications, such as polarimetric multispectral imaging and miniaturized polarimeter.In lithography, misalignment measurement with a large range and high precision in two dimensions for the overlay is a fundamental but challenging problem. For moiré-based misalignment measurement schemes, one potential solution is considered to be the use of circular gratings, whose formed moiré fringes are symmetric, isotropic, and aperiodic. However, due to the absence of proper analytical arithmetic, the measurement accuracy of such schemes is in the tens of nanometers, resulting in their application being limited to only coarse alignments. To cope with this problem, we propose a novel deep learning-based misalignment measurement strategy inspired by deep convolutional neural networks. The experimental results show that the proposed scheme can achieve nanoscale accuracy with micron-scale circular alignment marks. ATR inhibitor Relative to the existing strategies, this strategy has much higher precision in misalignment measurement and much better robustness to fabrication defects and random noise. This enables a one-step two-dimensional nanoscale alignment scheme for proximity, x-ray, extreme ultraviolet, projective, and nanoimprint lithographies.
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