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Journal of the Optical Society of... Jun 2024In this paper we analytically find out the expression for the wave vector and Poynting vector in the reflection domain for negative uniaxial material. We investigate the...
In this paper we analytically find out the expression for the wave vector and Poynting vector in the reflection domain for negative uniaxial material. We investigate the impact of the optical axis rotation and incident angle on the wave vector and Poynting vector reflected from the internal surface of lithium niobate crystal when the light is propagating from the denser anisotropic medium to the rarer isotropic medium. We derive the Brewster angle condition and discuss the walk-off between TE and TM polarized light. We explore where the wave vector and Poynting vector are parallel after reflection. In further analysis, we look into the phase differences between ordinary and extraordinary reflected light after total internal reflection from the internal surface of lithium niobate crystal. The necessary conditions for linear polarization and circular polarization have been established. The impact of optical axis orientation is also taken into consideration. The refractive index for the isotropic material for the desired polarization response has been found as 2.18, 2.1, and 2.03 at 632 nm, 1550 nm, and 3500 nm, respectively.
PubMed: 38856436
DOI: 10.1364/JOSAA.522592 -
Applied Optics May 2024Compact, magnetic field, sensing is proposed and demonstrated by combining the two Faraday rotation elements and beam displacement crystals within a micro-optical fiber...
Compact, magnetic field, sensing is proposed and demonstrated by combining the two Faraday rotation elements and beam displacement crystals within a micro-optical fiber circulator with a fiber reflector and ferromagnets to allow high contrast attenuation in an optical fiber arm. Low optical noise sensing is measured at =1550 as a change in attenuation, , of optical light propagating through the rotators and back. The circulator's double-pass configuration, using a gold mirror as a reflector, achieves a magnetic field sensitivity = / =(0.26±0.02) / with a resolution of =0.01 , over a detection range =0-89 . The circulator as a platform provides direct connectivity to the Internet, allowing remote sensing to occur. The method described here is amenable to multisensor combinations, including with other sensor technologies, particularly in future integrated waveguide Faraday optical circuits and devices, extending its utility beyond point magnetic field sensing applications.
PubMed: 38856331
DOI: 10.1364/AO.513826 -
Small (Weinheim An Der Bergstrasse,... Jun 2024Most 2D nonlinear optical (NLO) materials do not have an ultrawide bandgap, therefore, they are unsuitable for working in the deep-ultraviolet spectral range (<...
Most 2D nonlinear optical (NLO) materials do not have an ultrawide bandgap, therefore, they are unsuitable for working in the deep-ultraviolet spectral range (< 200 nm). Herein, the theoretical prediction of an excellent monolayer BePOH (ML-BPOH) is reported. DFT analyses suggest a low cleavage energy (≈45 meV per atom) from a naturally existed bulk-BPOH material, indicating feasible exfoliation. This novel 2D material exhibits excellent properties including an ultrawide bandgap (E) of 7.84 eV, and a strong second-order nonlinear susceptibility ( = 0.43 pm V), which is comparable to that of benchmark bulk-KBBF crystal (d = 0.45 pm V). The wide bandgap and large SHG effect of ML-BPOH are mainly derived from the (POH) tetrahedron. Notably, ML-BPOH exhibits an outstanding 50% variation in d under minor stress stimuli (±3%) due to rotation of structurally rigid (POH) tetrahedron. This indicates significant potential for application in material deformation monitoring.
PubMed: 38855996
DOI: 10.1002/smll.202404155 -
Natural Product Research Jun 2024Activation of silencing gene clusters is an important way to discover structurally novel compounds. In this study, three undescribed compounds were obtained from an...
Activation of silencing gene clusters is an important way to discover structurally novel compounds. In this study, three undescribed compounds were obtained from an engineered strain of sp. S35-LAL1. They include a polysubstituted cyclopentane with an unprecedented 10-carbon skeleton () and two glycerol esters ( and ). The structures of compounds were elucidated through analysis of their spectroscopic data including 1D, 2D NMR, optical rotation, and electronic circular dichroism (ECD).
PubMed: 38853409
DOI: 10.1080/14786419.2024.2364932 -
The Review of Scientific Instruments Jun 2024Experimental insight into the elementary processes underlying charge transfer across interfaces has blossomed with the wide-spread availability of ultra-high vacuum...
Integration of conventional surface science techniques with surface-sensitive azimuthal and polarization dependent femtosecond-resolved sum frequency generation spectroscopy.
Experimental insight into the elementary processes underlying charge transfer across interfaces has blossomed with the wide-spread availability of ultra-high vacuum (UHV) setups that allow the preparation and characterization of solid surfaces with well-defined molecular adsorbates over a wide range of temperatures. Within the last 15 years, such insights have extended to charge transfer heterostructures containing solids overlain by one or more atomically thin two dimensional materials. Such systems are of wide potential interest both because they appear to offer a path to separate surface reactivity from bulk chemical properties and because some offer completely novel physics, unrealizable in bulk three dimensional solids. Thick layers of molecular adsorbates or heterostructures of 2D materials generally preclude the use of electrons or atoms as probes. However, with linear photon-in/photon-out techniques, it is often challenging to assign the observed optical response to a particular portion of the interface. We and prior workers have demonstrated that by full characterization of the symmetry of the second order nonlinear optical susceptibility, i.e., the χ(2), in sum frequency generation (SFG) spectroscopy, this problem can be overcome. Here, we describe an UHV system built to allow conventional UHV sample preparation and characterization, femtosecond and polarization resolved SFG spectroscopy, the azimuthal sample rotation necessary to fully describe χ(2) symmetry, and sufficient stability to allow scanning SFG microscopy. We demonstrate these capabilities in proof-of-principle measurements on CO adsorbed on Pt(111) and on the clean Ag(111) surface. Because this setup allows both full characterization of the nonlinear susceptibility and the temperature control and sample preparation/characterization of conventional UHV setups, we expect it to be of great utility in the investigation of both the basic physics and applications of solid, 2D material heterostructures.
PubMed: 38842418
DOI: 10.1063/5.0205278 -
Nano Letters Jun 2024Light-matter strong coupling (LMSC) is an intriguing state in which light and matter are hybridized inside a cavity. It is increasingly recognized as an excellent way to...
Light-matter strong coupling (LMSC) is an intriguing state in which light and matter are hybridized inside a cavity. It is increasingly recognized as an excellent way to control material properties without any chemical modification. Here, we show that the LMSC is a powerful state for manipulating chiral nonlinear optical (NLO) effects through the investigation of second harmonic generation (SHG) circular dichroism. At the upper polariton band in LMSC, in addition to the enhancement of SHG by more than 1 order of magnitude, the responsivity to the handedness of circularly polarized light was largely modified, where sign inversion and increase of the dissymmetry factor were achieved. Quarter waveplate rotation analysis revealed that the LMSC clearly influenced the coefficients associated with chirality in the NLO process and also contributed to the enhancement of nonlinear magnetic dipole interactions. This study demonstrated that LMSC serves as a great platform for controlling chiral and magneto-optics.
PubMed: 38836611
DOI: 10.1021/acs.nanolett.4c01707 -
Multi-order orbital angular momentum mode generators based on integrated long-period fiber gratings.Optics Letters Jun 2024We propose integrated long-period fiber gratings (LPFGs) fabricated by a CO laser to realize a multi-channel and multi-order orbital angular momentum (OAM) mode...
We propose integrated long-period fiber gratings (LPFGs) fabricated by a CO laser to realize a multi-channel and multi-order orbital angular momentum (OAM) mode generator. The integrated LPFG is inscribed on multiple surfaces of the few-mode fiber (FMF) by rotating the fiber in the opposite direction at an angle θ. By controlling the rotation angle, the number of integrated LPFGs can be set. The selected rotation angle is 43 , which can integrate up to nine LPFGs, i.e., realizing that the number of channels for first-order orbital angular momentum (OAM) mode conversion is nine. The integrated LPFGs fabricated in this method allow a flexible design of channel spacing. In addition, the flexible selection of the integrated grating period achieves the simultaneous generation of multi-channel second-order and third-order OAM mode conversion. The multi-channel and multi-order OAM mode generators have important application in optical communication multiplexing systems and OAM sensing.
PubMed: 38824374
DOI: 10.1364/OL.520507 -
International Journal of Computer... Jun 2024Surgical robots effectively improve the accuracy and safety of surgical procedures. Current optical-navigated oral surgical robots are typically developed based on...
PURPOSE
Surgical robots effectively improve the accuracy and safety of surgical procedures. Current optical-navigated oral surgical robots are typically developed based on binocular vision positioning systems, which are susceptible to factors including obscured visibility, limited workplace, and ambient light interference. Hence, the purpose of this study was to develop a lightweight robotic platform based on monocular vision for oral surgery that enhances the precision and efficiency of surgical procedures.
METHODS
A monocular optical positioning system (MOPS) was applied to oral surgical robots, and a semi-autonomous robotic platform was developed utilizing monocular vision. A series of vitro experiments were designed to simulate dental implant procedures to evaluate the performance of optical positioning systems and assess the robotic system accuracy. The singular configuration detection and avoidance test, the collision detection and processing test, and the drilling test under slight movement were conducted to validate the safety of the robotic system.
RESULTS
The position error and rotation error of MOPS were 0.0906 ± 0.0762 mm and 0.0158 ± 0.0069 degrees, respectively. The attitude angle of robotic arms calculated by the forward and inverse solutions was accurate. Additionally, the robot's surgical calibration point exhibited an average error of 0.42 mm, with a maximum error of 0.57 mm. Meanwhile, the robot system was capable of effectively avoiding singularities and demonstrating robust safety measures in the presence of minor patient movements and collisions during vitro experiment procedures.
CONCLUSION
The results of this in vitro study demonstrate that the accuracy of MOPS meets clinical requirements, making it a promising alternative in the field of oral surgical robots. Further studies will be planned to make the monocular vision oral robot suitable for clinical application.
PubMed: 38822980
DOI: 10.1007/s11548-024-03161-8 -
Detection of optical properties of chiral substances by a photoconductive THz polarization detector.Spectrochimica Acta. Part A, Molecular... Oct 2024Chiral enantiomers have significant differences in biochemical functions. The use of THz wave polarization detection to characterize the optical properties of chiral...
Chiral enantiomers have significant differences in biochemical functions. The use of THz wave polarization detection to characterize the optical properties of chiral substances is of great significance to the development of life science and the identification and application of chiral substances. However, the traditional polarization detection procedures of THz waves are complex, which limits the study of chiral substances. Herein, we proposed a high-sensitivity THz polarization detector, which can simultaneously obtain the change information of amplitude, phase, and polarization state through a single measurement. The optical rotation and elliptical angle of solid and liquid D/L-Glutamic acid 5-methyl ester in the THz band are studied. Then it is verified that anisotropic interference may occur in the preparation of solid samples. Finally, the effects of sample content and thickness on polarization are obtained. The experimental results show that different chirality has the opposite effect on the state of polarization, and the difference between chiral enantiomers can be detected by this method. This work is of great significance for understanding the optical properties of chiral substances and promoting the development of chiral recognition.
PubMed: 38820816
DOI: 10.1016/j.saa.2024.124490 -
Clinical Spine Surgery May 2024A prospective study.
STUDY DESIGN
A prospective study.
OBJECTIVE
To measure 3-dimensional cervical range of motion (ROM) by noninvasive optical tracking-based motion-capture technology in patients undergoing laminoplasty, and to elucidate the postoperative effects of laminoplasty on cervical mobility.
SUMMARY OF BACKGROUND DATA
Cervical laminoplasty is a motion-sparing decompression surgery for degenerative cervical myelopathy. Unlike cervical laminectomy and fusion, the true postoperative impact of laminoplasty on neck motion has not been well studied.
METHODS
Participants comprised 25 patients undergoing double-door cervical laminoplasty for degenerative cervical myelopathy in a single center. Maximum flexion/extension, left/right rotation, and left/right side bending were recorded using the motion-capture device preoperatively and 3 months postoperatively. ROMs in 3 orthogonal axes were calculated. Preoperative differences in C2-7 Cobb angles on lateral flexion/extension x-rays were also measured as the radiologic ROM to assess reliability. Preoperative and 1-year postoperative Japanese Orthopaedic Association score, Neck Disability Index [NDI], and Euro-QOL were recorded, and correlations with ROMs were assessed.
RESULTS
Preoperative mean (±SD) ROMs for flexion/extension, rotation, and side bending were 90±17, 107±16, and 53±17 degrees, respectively. Although radiologic sagittal ROM measurement showed a smaller range than motion capture, averaging 36±13 degrees, a moderate to strong correlation between radiologic and motion capture values was observed (R=0.57, P=0.003). Preoperative NDI showed a negative correlation with coronal ROM (rho=-0.547, P=0.02). Postoperative ROM showed a significant reduction in rotation (95±16 degrees, P=0.002) but not in flexion/extension or side bending.
CONCLUSIONS
Three-dimensional motion-capture analysis allowed reliable measurement of cervical ROM. Rotational ROM was significantly reduced after laminoplasty, showing that cervical kinematics are still significantly altered.
PubMed: 38820120
DOI: 10.1097/BSD.0000000000001641