Ebsenbuck2833

Our diffuser design outperforms the MLA used in LFM, providing more uniform resolution over a larger volume, both laterally and axially.Many technologies in quantum photonics require cryogenic conditions to operate. However, the underlying platform behind active components such as switches, modulators and phase shifters must be compatible with these operating conditions. To address this, we demonstrate an electro-optic polarisation converter for 1550 nm light at 0.8 K in titanium in-diffused lithium niobate waveguides. To do so, we exploit the electro-optic properties of lithium niobate to convert between orthogonal polarisation modes with a fiber-to-fiber transmission >43%. We achieve a modulation depth of 23.6±3.3 dB and a conversion voltage-length product of 28.8 V cm. This enables the combination of cryogenic photonics and active components on a single integration platform.We report on a highly sensitive measurement of the relative humidity of air, which utilizes a guided-mode resonance (GMR) of a multilayer dielectric structure (MDS) and the spectral interference of s- and p-polarized waves reflected from the MDS. We employ the MDS represented by four bilayers of TiO2/SiO2 with a termination layer of TiO2 and demonstrate that the GMR shows up as a shallow and asymmetric dip. The GMR enables us to measure the relative humidity (RH) of air with sensitivities of 0.031-0.114 nm/%RH. In addition, by employing a birefringent crystal of mica, which modifies the phase difference between the polarized waves, the GMR is transformed into the resonance with a sharp dip, and the measured sensitivity is enhanced to 0.120 nm/%RH at 81 %RH. We also determined the sensitivity to the refractive index and the figure of merit as high as 8000 nm/refractive index unit (RIU) and 702 RIU-1, respectively. The results demonstrate that the GMR based sensor employing the MDS and the spectral interference of polarized waves with their phase difference appropriately adjusted enables a highly sensitive, hysteresis-free humidity measurement, characterized by a high FOM. #link# Humidity sensors employing dielectric multilayers thus represent an effective alternative to available sensors, with advantages such as better mechanical and chemical stability.The dissipative squeezing mechanism is an effective method to generate the strong squeezing, which is important in the precision metrology. Here, we propose a practical method to achieve arbitrary bosonic squeezing via introducing frequency modulation into the coupled harmonic resonator model. We analyze the effect of frequency modulation and give the analytical and numerical squeezing results, respectively. To measure the accurate dynamic squeezing in our proposal, we give a more general defination of the relative squeezing degree. Finally, the proposed method is extended to generate the strong mechanical squeezing (>3 dB) in a practical optomechanical system consisting of a graphene mechanical oscillator coupled to a superconducting microwave cavity. The result indicates that the strong mechanical squeezing can be effectively achieved even when the mechanical oscillator is not initially in its ground state. The proposed method expands the study on nonclassical state and does not need the bichromatic microwave driving technology.We investigate the coherence of plasma-based soft X-ray laser (XRL) for different conditions that can alter the electron density in the gain region. We first measure the source temporal coherence in amplified spontaneous emission (ASE) mode. We develop a data analysis procedure to extract both its spectral width and pulse duration. These findings are in agreement with the spectral line shape simulations and seeded operation experimental results. Utilizing the deduced spectral width and pulse duration in a one-dimensional Bloch-Maxwell code, we reproduce the experimental temporal coherence properties of the seeded-XRL. Finally, we demonstrate efficient lasing in ASE and seeded mode at an electron density two times higher than the routine conditions. In this regime, using Bloch-Maxwell modeling, we predict the pulse duration of the seeded XRL to be ∼500fs.Based on the angular spectrum of high order off-axis Airy vortex beams (AiVBs), Goos-Hänchen (GH) shifts and Imbert-Fedorov (IF) shifts near the Brewster angle are numerically calculated. It is found that both GH and IF shifts increase with the increase of the vortex's topological charge of AiVBs. The influences of the vortex's positions on GH and IF shifts are studied for the case of the topological charge m = 1. Enpp-1-IN-1 datasheet of the off-axis vortex show that the influences of the vortex's position on shifts are inversely proportional to the distance between the vortex's position and the origin point.In this paper, a deep learning-based detection scheme is proposed for the visible light communication (VLC) systems using generalized spatial modulation (GenSM). link2 In the proposed detection scheme, a deep neural network consisting of several neural layers is applied to detect the received signals. By integrating the signal processing modules of the conventional detection schemes into one deep neural network, the proposed scheme is able to extract the information bits from the received signals efficiently. After offline training, the proposed detection scheme can serve as a promising detection method for the VLC system with GenSM. Simulation results validate that the proposed detection scheme is capable of achieving superior detection error performance than conventional detection schemes at acceptable complexity.We analyze the similarity between the geometric phase and the phase from parity-time symmetric modulation and argue that they can be integrated together in nanostructures. We provide a simple hybrid metasurface design to demonstrate the simultaneous utilization of these phases in manipulating the diffraction of optical field. Polarization-sensitivity of the hybrid phase is also discussed. This study provides a more advanced method of achieving polarization-dependent optical manipulation in artificial nanostructures.Optical retrieval of the structure of transparent objects at the nanoscale requires adapted techniques capable of probing their interaction with light. Here, we considered a method based on calibration of the defocusing with partially coherent illumination and explored its phase retrieval capability over a wide range of illumination angles. We imaged (1) commercial dielectric nanospheres to assess the phase calibration when measured along the optical axis, (2) custom-made nano-steps micropatterned in a glass substrate to assess the phase calibration when measured along the transversal axis, and (3) human cancer cells deposited on a glass substrate to assess the results of the calibration on complex transparent 3-dimensional samples. link3 We first verified the model prediction in the spatial frequency domain and subsequently obtained a consistent and linear phase-calibration for illumination numerical apertures ranging from 0.1 to 0.5. Finally, we studied the dependence of the phase retrieval of a complex nanostructured object on the illumination aperture.We report a simple single-pixel imaging system with a low mean squared error in the entire terahertz frequency region (3-13 THz) that employs a thin metallic ring with a series of directly perforated random masks and a subpixel mask digitization technique. This imaging system produces high pixel resolution reconstructed images, up to 1200 × 1200 pixels, and imaging area of 32 × 32 mm2. It can be extended to develop advanced imaging systems in the near-ultraviolet to terahertz region.A new kind of partially coherent vector vortex beam, namely, the partially coherent radially polarized (PCRP) beam with multiple off-axis vortices, is introduced, and the average intensity distributions of such vortex beam focused by a thin lens are investigated theoretically. It is novelty that the off-axis vortices will induce the focal intensity redistribution and reconstruction, while this remarkable characteristic will be vanished in the case of a very low coherence. In view of this distinctive feature, a new method has been put forward to shape or modulate the focal intensity distribution by elaborately tailoring the multiple off-axis vortices as well as the coherence length. More importantly, some peculiar focal fields with novel structures, such as bar-shaped, triangle-shaped, square-shaped, and pentagon-shaped hollow profiles or flat-top foci, are obtained. Our results indicate that modulating the multiple off-axis vortices provides an additional degree of freedom for focus shaping.Detecting low energy photons, such as photons in the long-wave infrared range, is a technically challenging proposition using naturally occurring materials. In order to address this challenge, we herein demonstrate a micro-bolometer featuring an integrated metamaterial absorber (MA), which takes advantage of the resonant absorption and frequency selective properties of the MA. Importantly, our micro-bolometer exhibits polarization insensitivity and high absorption due to a novel metal-insulator-metal (MIM) absorber design, operating at 8-12 µm wavelength. The metamaterial structures we report herein feature an interconnected design, optimized towards their application to micro-bolometer-based, long-wave infrared detection. The micro-bolometers were fabricated using a combination of conventional photolithography and electron beam lithography (EBL), the latter owing to the small feature sizes within the design. The absorption response was designed using the coupled mode theory (CMT) and the finite integration te long-wave infrared range through the integration of infrared MAs with micro-bolometers.A vector optical-chirp-chain (OCC) Brillouin optical time-domain analyzer (BOTDA) based on complex principal component analysis (CPCA) is proposed and experimentally demonstrated by employing a four-tone OCC probe with two orthogonal polarization states. The polarization-fading-free complex Brillouin spectrum (CBS) of the vector OCC-BOTDA is obtained by combining the amplitude and phase response spectra of the probe wave at both Brillouin gain and loss region. We utilize the CPCA method to determine the Brillouin frequency shift (BFS) directly using the measured CBS, and the sensing accuracy is improved by a factor of up to 1.4. The distributed temperature sensing is demonstrated over a 20 km standard single-mode fiber with a 6 m spatial resolution and less than 1 MHz frequency uncertainty under 10 times of trace averaging.We present a reference-free method to determine electrical parameters of thin conducting films by steady state transmission-mode terahertz time-domain spectroscopy (THz-TDS). We demonstrate that the frequency-dependent AC conductivity of graphene can be acquired by comparing the directly transmitted THz pulse with a transient internal reflection within the substrate which avoids the need for a standard reference scan. The DC sheet conductivity, scattering time, carrier density, mobility, and Fermi velocity of graphene are retrieved subsequently by fitting the AC conductivity with the Drude model. This reference-free method was investigated with two complementary THz setups one commercial fibre-coupled THz spectrometer with fast scanning rate (0.2-1.5 THz) and one air-plasma based ultra-broadband THz spectrometer for greatly extended frequency range (2-10 THz). Certain propagation correction terms for more accurate retrieval of electrical parameters are discussed.