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- 摘要
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- 实验方案
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A novel star shape photonic crystal fiber for low loss terahertz pulse propagation
摘要： An extremely low loss circle-based star shape photonic crystal fiber (CS-PCF) has been proposed for terahertz (THz) spectrum. A dielectric material TOPAS has been used for constructing the proposed model. Some important parameters for the proposed waveguide have been investigated a wide THz spectrum ranging from 0.5 to 2.50 THz. The simulation result exhibits an extremely-low material loss of 0.01607 cm-1 and a large effective area of 1.386 × 106 μm2 at 1.0 THz frequency with 55% core porosity. In addition, the proposed structure establishes comparatively higher core power fraction maintaining lower scattering loss about 1.235 × 10-15 dB/cm and 91.97% of bulk absorption material loss at the same operating frequency. From the above results, it is anticipated that proposed CS-PCF model of the THz waveguide will make the conventional communication very effective over the current designs.
关键词： Effective material Loss,Scattering Loss,Power Fraction,THz Application,Single Mode Fiber
更新于2025-09-23 15:21:01
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On-chip single-mode CdS nanowire laser
摘要： By integrating a free-standing cadmium sulfide (CdS) nanowire onto a silicon nitride (SiN) photonic chip, we demonstrate a highly compact on-chip single-mode CdS nanowire laser. The mode selection is realized using a Mach-Zehnder interferometer (MZI) structure. When the pumping intensity exceeds the lasing threshold of 4.9 kW/cm2, on-chip single-mode lasing at ~518.9 nm is achieved with a linewidth of 0.1 nm and a side-mode suppression ratio of up to a factor of 20 (13 dB). The output of the nanowire laser is channelled into an on-chip SiN waveguide with high efficiency (up to 58%) by evanescent coupling, and the directional coupling ratio between the two output ports can be varied from 90 to 10% by predesigning the coupling length of the SiN waveguide. Our results open new opportunities for both nanowire photonic devices and on-chip light sources and may pave the way towards a new category of hybrid nanolasers for chip-integrated applications.
关键词： Mach-Zehnder interferometer,single-mode lasing,nanowire laser,on-chip nanophotonics,silicon nitride waveguide
更新于2025-09-23 15:19:57
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Universal Output Characteristics of Single-Mode Operation in Low-Loss Large- <i>V</i> -Number Multimode Waveguide Lasers with Transverse Spatial Hole Burning
摘要： We study the performance limit of single-mode operation in low-loss large-V-number planar waveguide lasers, with transverse spatial hole burning as the dominating mechanism for transverse-mode competition. By introducing normalized variables, we develop a simple semianalytical model to describe the universal output characteristics of single-mode emission before the onset of high-order modes, which can be easily scaled to a wide range of laser configuration parameters. Our model is validated using exact numerical solutions, which show applicability beyond that of the low-loss approximation. Our analysis establishes a minimum criterion of the loss ratio between the fundamental and first higher-order mode for a robust single-mode operation. This criterion is much weaker than that of conventional wisdom based on the pure wave-propagation argument, which we attribute to a resonator enhancement effect. Our universal outcome can be denormalized to establish the relationship between single-mode extraction efficiency and optimum output coupling in a multimode laser with arbitrary modal loss ratios over a wide range of single-pass unsaturated gain and loss.
关键词： single-mode operation,transverse spatial hole burning,multimode waveguide lasers,large-V-number,low-loss
更新于2025-09-23 15:19:57
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Femtosecond laser direct written off-axis fiber Bragg gratings for sensing applications
摘要： First order off-axis fiber Bragg gratings (FBGs) were fabricated in a standard single mode fiber (SMF-28e) through femtosecond laser direct writing. A minimum offset distance between the grating and core center of 2.5 μm was found to create a multimode section, which supports two separate fiber modes (LP0,1 and LP1,1), each split into two degenerate polarization modes. The resulting structure breaks the cylindrical symmetry of the fiber, introducing birefringence (≈10?4) resulting in a polarization dependent Bragg wavelength for each mode. Based on the modal and birefringence behavior, three off-axis FBGs were fabricated with 3.0, 4.5 and 6.0 μm offsets from the core center, and then characterized in strain, temperature, and curvature. The tested off-axis FBGs exhibited a similar strain sensitivity of ~1.14 pm/μ? and a temperature sensitivity of ~12 pm/C. The curvature and orientation angle were simultaneously monitored by analyzing the intensity fluctuation and the wavelength shift of the LP1,1 Bragg resonance. A maximum curvature sensitivity of 0.53 dB/m?1 was obtained for the off-axis FBG with a 3.0 μm offset.
关键词： optical fiber sensors,femtosecond laser direct writing,single mode fiber,off-axis fiber Bragg gratings,Birefringence
更新于2025-09-23 15:19:57
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Optical fiber temperature sensor based on a Mach-Zehnder interferometer with single-mode-thin-core-single-mode fiber structure
摘要： A Mach-Zehnder interferometer for measurement of temperature is proposed and experimentally demonstrated, which consists of two sections of single mode fiber (SMF) and a section of thin core fiber spliced between the two SMFs. The two welding areas are heated and stretched to improve the split and recombination of light. The wavelength of the resonant dip will shift when temperature varies due to the thermo-optic and thermal expansion effect. The experimental results show that a temperature sensitivity of 65 pm/○C with a linear correlation coefficient of 0.996 can be achieved in a temperature range from 25 ○C to 80 ○C. Due to its ease of manufacture, low cost, and high sensitivity, the fiber optic temperature sensor is suitable for temperature measurement applications.
关键词： single-mode-thin-core-single-mode fiber structure,Mach-Zehnder interferometer,Optical fiber temperature sensor
更新于2025-09-19 17:13:59
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Theoretical analysis for exploring the optical performance of solid-core polymer based microstructured optical fibers
摘要： Polymer based microstructured optical fibers (MPOFs) like their silica counterparts guides the light through the use of array of wavelength-scale microstructures in the cross-section, and offers pivotal dominance over both polymer optical fibers (POFs) as well as air/silica microstructured optical fibers (MOFs). We aspire to investigate the optical characteristics of the solid-core MOFs based on polymer material by using an efficient theoretical model. Theoretical evidences to demonstrate that fiber support only single mode are explored and cut-off conditions are identified. We evaluate the effective index of higher-order mode (HOM) for the solid-core MPOF at terahertz (THz) regime, and the coupling properties of long-period gratings (LPGs) in MPOF are also examined. Further, the sensitivity coefficient is studied for realizing the efficient coupling in the evanescent field based applications. Theoretical results are compared with those as reported in the literature. Relative errors are also included.
关键词： Microstructured optical fibers,Single-mode,Long-period gratings,Polymer optical fibers,Second-order mode,Terahertz
更新于2025-09-19 17:13:59
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Review of the technology of a single mode fiber coupling to a laser diode
摘要： In this paper, the technology of a single mode fiber coupling to a semiconductor laser diode has been summarized and the latest developments in the bulk optics coupling scheme and the microlens fiber coupling scheme have been reviewed. The review has focused on optimizing the optical structure and the coupling parameters to improve the coupling efficiency and packaging performance. The advanced manufacturing technology as well as common modeling methods and applications of coupling systems have also been reviewed. Finally, the paper has summarized the key technologies of a single mode fiber coupling to a laser diode and its direction of development in the future.
关键词： Single mode fiber,Coupling efficiency,Bulk optics,Optical structure,Microlens fiber,Manufacturing technology,Laser diode
更新于2025-09-19 17:13:59
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Laser oscillation at an intended wavelength from a distributed feedback structure on anisotropic organic crystals
摘要： An organic laser device is constructed as distributed feedback (DFB) type using an anisotropic single crystal of an organic semiconductor oligomer BP3T. The DFB structure is formed on top of the crystal via an interference exposure technique of a positive type photoresist. In the DFB structure, both the phase matching condition and waveguide condition must be fulfilled. Under these conditions, the effective refractive indices can be precisely predicted for a BP3T crystal, and they vary depending upon the crystal thickness. As a result, the device produces a single-mode laser oscillation at an intended wavelength (typically ～569 nm). The present study enables us to design a down-to-earth laser device based on an anisotropic organic semiconductor crystal toward practical use.
关键词： organic laser,single-mode laser oscillation,anisotropic organic crystal,BP3T,distributed feedback
更新于2025-09-19 17:13:59
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Continuous-wave 6-dB-squeezed light with 2.5-THz-bandwidth from single-mode PPLN waveguide
摘要： Terahertz (THz)-bandwidth continuous-wave (CW) squeezed light is essential for integrating quantum processors with time-domain multiplexing (TDM) by using optical delay line interferometers. Here, we utilize a single-pass optical parametric amplifier (OPA) based on a single-spatial-mode periodically poled ZnO:LiNbO3 waveguide, which is directly bonded onto a LiTaO3 substrate. The single-pass OPA allows THz bandwidth, and the absence of higher-order spatial modes in the single-spatial-mode structure helps avoid degradation of squeezing. In addition, the directly bonded ZnO-doped waveguide has durability for high-power pump and shows small photorefractive damage. Using this waveguide, we observe CW 6.3-dB squeezing at 20-MHz sideband by balanced homodyne detection. This is the first realization of CW squeezing with a single-pass OPA at a level exceeding 4.5 dB, which is required for the generation of a two-dimensional cluster state. Furthermore, the squeezed light shows 2.5-THz spectral bandwidth. The squeezed light will lead to the development of a high-speed on-chip quantum processor using TDM with a centimeter-order optical delay line.
关键词： terahertz-bandwidth,quantum information processing,squeezed light,continuous-wave,single-mode PPLN waveguide
更新于2025-09-19 17:13:59
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Polarization dependence of optical properties of single-mode polymer optical waveguides fabricated under different processes at 1310/1550 nm
摘要： We experimentally investigate the polarization dependence of the optical properties of single-mode polymer optical waveguides. We compare two types of waveguides composed of the same polymer materials: step-index square-core waveguides fabricated using the direct curing method and graded-index (GI) circular-core waveguides fabricated using the Mosquito method. We demonstrate that the GI circular-core single-mode waveguides exhibit remarkably small dependence of optical loss on the polarization angle, which is less than 0.1-dB polarization dependent loss (PDL) at both 1310 and 1550 nm wavelengths. This steady polarization property is attributed to the material stress free to the composing polymers during the fabrication process of the Mosquito method and to parabolic GI profile formed in symmetric circular core.
关键词： single-mode polymer optical waveguides,optical interconnections,step-index,the Mosquito method,polarization dependent optical property,graded-index,direct curing method
更新于2025-09-19 17:13:59