Reynoldswilhelmsen5926

We have proposed a broadband hybrid light source that combines a super luminescent diode (SLD) and thulium-doped fiber amplifier (TDFA) and operates in the 1.8 µm band. This light source can improve the characteristics of the output spectrum by amplifying the output light of the SLD with TDFA. In this study, we investigate the dependence of the output spectral characteristics of the hybrid broadband light source on the thulium-doped fiber (TDF) length used in the TDFA as well as the output spectra of three newly developed SLDs of 1660, 1690, and 1730 nm bands. In the evaluation of the output bandwidth, there are various definitions of output bandwidth, but we adopted the bandwidth with power density of over -40dBm/0.1nm. This is because it is possible to evaluate in this band with a dynamic range of "30 dB/0.1 nm" by using a general optical spectrum analyzer. The hybrid light source achieves the bandwidth of 332 nm, from 1579 to 1911 nm, and a high total output power of over 15 dBm. The maximum ripple was less than ∼0.1dB, which is similar to the maximum value of that of the SLD, without any deterioration in the ripple characteristics owing to the hybrid configuration of the SLD and TDFA.A novel, to the best of our knowledge, device scheme for a silicon-nanowire flat-spectral-band wavelength optical filter is proposed and theoretically demonstrated. The proposed wavelength filter is composed of cascade-connected multiple delayed interference optical delay lines, together with several multimode interference couplers with symmetric and asymmetric splitting ratios. Theoretical calculations based on analytic and numerical simulations exhibit flatband spectra over a wavelength range of >80 nm with potentially better production yield for arbitrary channel spacing.Extreme ultraviolet (EUV) lithography is a new generation of integrated circuit manufacturing technology with great development prospects. EUV lithography has more significant demand for high exposure latitude (EL) due to greater requirements for the stability of the light source. Source and mask optimization (SMO) technology is widely used to compensate for imaging distortion. In this paper, we propose an EL-aware SMO (ELASMO) method that uses a low-resist threshold sensitivity (LRS) penalty function to improve the EL in EUV lithography. Compared to conventional SMO, the proposed ELASMO method can significantly enhance the aerial image contrast, improve the EL, and enlarge the process window while ensuring high imaging fidelity.The concentration-path-length product (CL) image of the leaking gas cloud measured by the passive Fourier transform infrared (FTIR) scanning remote-sensing imaging system has a low resolution. Gas cloud diffusion is affected by wind speed and direction, which makes it difficult to trace the source of a leakage. Therefore, we propose a method to reconstruct the CL image of the leaking gas cloud applied to the passive FTIR scanning remote-sensing imaging system. First, bicubic interpolation is employed to upsample the low-resolution CL image of gas clouds. Second, the maximum noise-equivalent concentration-path-length (NECL) product is used as a threshold to segment the high-resolution gas cloud image. Third, image morphology processing and the evaluation criteria of the leaking gas cloud are applied to detect the leaking gas cloud. Finally, the high-resolution CL image of the leaking gas cloud is superimposed onto the background image. The effectiveness of the reconstruction method is proven by the SF6 remote-sensing experiment and simulation. The results show that the proposed method should be effectively implemented to reconstruct the high-resolution CL image of the leaking gas cloud. The reconstructed leaking gas cloud plume, as well as the location of the leakage source, are quite obvious. The reconstruction method has been successfully applied to passive FTIR scanning remote-sensing imaging systems, with high accuracy, in real time, and with robustness.Fiber optical power splitters (OPSs) have been widely employed in optical communications, optical sensors, optical measurements, and optical fiber lasers. It has been found that OPSs with variable power ratios can simplify the structure and increase the flexibility of optical systems. In this study, a variable-fiber OPS based on a triangular prism is proposed and demonstrated. By adjusting the output beam width of the prism, the power ratio can be continuously tuned. The optical simulations show that the horizontal displacement design is better than the traditional tilt angle design. Our scheme combines a dual-fiber collimator, a focus lens, and a triangular prism with a vertex angle of 120°. By changing the axial displacement of the prism, the power splitting ratio can be altered from 5050 to 9010. The polarization and wavelength dependence of the variable OPS were also investigated.High-speed wireless communication is necessary in our personal lives, in both working and living spaces. This paper presents a scheme for wireless optical modulation format recognition (MFR) based on the Hough transform (HT). The HT is used to project constellation diagrams onto another space for efficient feature extraction. Constellation diagrams are obtained at optical signal-to-noise ratios (OSNR) ranging from 5 to 30 dB for eight different modulation formats (2/4/8/16 phase-shift keying and 8/16/32/64 QAM). Different classifiers are used for the task of MFR AlexNet, VGG16, and VGG19. A study of the effect of varying the number of samples on the accuracy of the classifiers is provided for each modulation format. To evaluate the proposed scheme, the efficiency of the three classifiers is studied at different values of OSNR. The obtained results reveal that the proposed scheme succeeds in identifying the wireless optical modulation format blindly with a classification accuracy up to 100%, even at low OSNR values less than 10 dB.The referenced paper [Appl. Opt.60, 3170 (2021)APOPAI0003-693510.1364/AO.420143] has been retracted by the authors.The imaging of a large area scene is difficult to achieve for a single camera. Alternatively, a virtual large aperture can be synthesized by sub-aperture cooperation. We propose a solution through the combination of a coded aperture snapshot spectral imager and coprime array. This method reduces the amount of data by using a smaller sub-aperture for sampling. The position of the sub-aperture is determined according to the element distribution of the coprime array, so that the data obtained from each sampling are about the target object and its adjacent area, which can ensure high reconstruction accuracy. The feasibility of coprime sub-aperture sampling is verified by numerical simulation.A power-balanced hybrid optical imaging system has a diffractive computational camera, introduced in this paper, with image formation by a refractive lens and multilevel phase mask (MPM). This system provides a long focal depth with low chromatic aberrations thanks to MPM and a high energy light concentration due to the refractive lens. We introduce the concept of optical power balance between the lens and MPM, which controls the contribution of each element to modulate the incoming light. Additional features of our MPM design are the inclusion of the quantization of the MPM's shape on the number of levels and the Fresnel order (thickness) using a smoothing function. To optimize the optical power balance as well as the MPM, we built a fully differentiable image formation model for joint optimization of optical and imaging parameters for the proposed camera using neural network techniques. We also optimized a single Wiener-like optical transfer function (OTF) invariant to depth to reconstruct a sharp image. We numerically and experimentally compare the designed system with its counterparts, lensless and just-lens optical systems, for the visible wavelength interval (400-700) nm and the depth-of-field range (0.5-∞ m for numerical and 0.5-2 m for experimental). We believe the attained results demonstrate that the proposed system equipped with the optimal OTF overcomes its counterparts--even when they are used with optimized OTF--in terms of the reconstruction quality for off-focus distances. The simulation results also reveal that optimizing the optical power balance, Fresnel order, and the number of levels parameters are essential for system performance attaining an improvement of up to 5 dB of PSNR using the optimized OTF compared to its counterpart lensless setup.The design, fabrication, and demonstration of a planar two-dimensional-crossed reflective diffractive grating are proposed to construct a novel optical configuration, to the best of our knowledge, potentially applied for atom cooling and trapping in a magneto-optical trap. Based on the proposed single-beam single-exposure scheme by means of an orthogonal two-axis Lloyd's mirrors interferometer, we rapidly patterned a ∼1µm period grating capable of providing a uniform intensity of the diffracted beams. The key structural parameters of the grating including the array square hole's width and depth were determined, aiming at providing a high energy of the diffracted beams to perform the atom cooling and trapping. Epacadostat mouse To guarantee the diffracted beams to be overlapped possibly, we adopted a polarized beam splitter to guide the optical path of the incident and zero-order diffracted beams. Therefore, one zero-order diffracted beam with a retroreflected mode and four first-order diffracted beams with appropriate optical path constructed a three-dimensional optical configuration of three orthogonal pairs of counterpropagating beams. Finally, three pairs of the counterpropagating cooling laser beams with 9 mm diameter and >10% diffraction efficiencies were achieved, and the circular polarization chirality, purity, and compensation of the desired diffracted beams are further evaluated, which preliminarily validated a high applicability for the magneto-optical trap system.In this paper, an underwater fiber-optic sensor based on surface plasmon resonance (SPR) and multimode interference (MMI) is presented for simultaneous measurement of salinity and pressure. This sensor is based on a single-mode-multimode-single-mode-multimode-single-mode structure with a gold film deposited on the middle single-mode fiber and the fiber structure is wrapped around an elastic cylinder to constitute a sensing head. In the fiber structure, the SPR region produces a resonance dip to measure salinity, and the independent MMI region achieves narrow and salinity-insensitive interference dips to measure pressure. Performance of the sensor is predicted by calculation, and the MMI spectrum is simulated by using the finite-difference beam propagation method. By experimental tests for salinity and pressure, the sensitivities of 0.36 nm/‰ and -1.42nm/MPa are achieved, respectively, and the cross talk is also proved to be insignificant. This study provides an important application direction for SPR-MMI sensors and a prospective method for ocean detection.At various temperatures, ranging from 25°C to 50°C, we characterized two types of photodetectors based on surface-state absorption in silicon (1) contactless integrated photonic probes (CLIPPs) and (2) normal-incidence photoconductors. Both types of photodetectors exhibited temperature-dependent AC admittance without illumination. With illumination at telecommunication wavelengths near 1550 nm, in the temperature range we measured, the photoresponse of CLIPPs, i.e., the variance of admittance due to illumination, was relatively insensitive to temperature changes; in comparison, the temperature dependence of the photoresponse of normal-incidence photoconductors was more pronounced-their responsivity increased as temperature raised.