共查询到20条相似文献,搜索用时 62 毫秒
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2-μm single longitudinal mode GaSb-based laterally coupled distributed feedback laser with regrowth-free shallow-etched gratings by interference lithography 下载免费PDF全文
We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio(SMSR) as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature(uncoated facet). A low threshold current density of 230 A/cm~2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature. 相似文献
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本文提出一种在同一段少模光纤上写入两个不同周期Λ1和Λ2的长周期光纤光栅构成叠栅的方法,实现了纤芯基模LP_(01)向高阶纤芯模LP_(11)模式转换的宽带宽的新型的全光纤模式转换器.利用有限元法和耦合模理论建立了模式转换器的理论分析模型.数值仿真分析了叠栅中两个子光栅周期间隔、光栅长度、耦合系数等光栅参数对模式转换器的影响.仿真分析和实验结果表明,通过改变两个子光栅的周期间隔来改变两个损耗峰的位置,形成一个损耗峰,从而可以实现宽带宽的模式转换器,其10dB带宽约是单栅的2倍.与传统的模式转换器相比,该转换器带宽宽、转换效率高,尺寸小、抗干扰能力强,可以在模分复用系统和光通信中得到广泛的应用. 相似文献
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Ronald Millett Henry Schriemer Trevor Hall Karin Hinzer 《Optical and Quantum Electronics》2008,40(14-15):1239-1245
We demonstrate the results of an analysis of laterally coupled distributed feedback (LC-DFB) lasers with higher order gratings, including the effects of radiating partial waves. For a given fabrication resolution, first-order gratings, if they can be reliably manufactured, always provide the strongest coupling. However, at resolutions requiring higher order gratings, if duty cycles of >0.5 are used, the lowest grating order is not always the one with the strongest coupling. An analysis of the rounding of the grating teeth showed that the required threshold gain was increased by nearly 20% when the rectangular grating was rounded in fabrication. 相似文献
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Hirohisa Yokota Takahiro Hasegawa Yoshitaka Satoda Eiichi Sugai Yutaka Sasaki 《Optical Review》1999,6(3):173-179
Fused optical fiber grating couplers (FGCs), in which Bragg gratings are written in the coupling regions of fused optical fiber couplers with tapered shapes along them are theoretically and experimentally investigated. By coupled mode analysis considering these tapered shapes, the drop efficiencies of the FGCs, which are inherently zero for the normal fiber couplers without grating, are calculated. The grating offset, which is the difference between the centers of grating and the coupler taper, is found to be effective to increase the drop efficiency of the FGC. It is determined that the tapered shapes influence the wavelength dependence of the drop efficiency and tolerate the grating offset precision. Apodizations for the grating of FGC are found to be effective in suppressing side lobes of the drop efficiency. Measurement of the wavelength characteristics of drop efficiency and the temperature characteristics of drop wavelength of the fabricated fused FGC confirm that the lightwave with specific wavelength can be dropped by the FGC and that the temperature dependence of the drop wavelength is similar to that of Bragg wavelength changes of usual fiber Bragg gratings. 相似文献
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R. Halir L. Zavargo-Peche D.-X. Xu P. Cheben R. Ma J. H. Schmid S. Janz A. Densmore A. Ortega-Mo?ux í. Molina-Fernández M. Fournier J.-M. Fédeli 《Optical and Quantum Electronics》2012,44(12-13):521-526
Surface grating couplers enable efficient coupling of light between optical fibers and planar waveguide circuits. While traditional grating designs require two etch steps for efficient coupling to silicon-on-insulator waveguides, recently proposed subwavelength structured gratings can achieve the same coupling efficiencies with a single etch step, thereby significantly reducing fabrication complexity. Here we demonstrate that such couplers can be fabricated on a large scale with ultra-violet lithography, achieving a 5?dB coupling efficiency at 1,550?nm. Through both simulations and experiments we give physical insight on how pattern fidelity impacts the performance of these couplers, and propose strategies to deal with inevitable process variations. 相似文献
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Study of the behaviour of the fibre Bragg grating fabricated with cladding mode suppression fibre 下载免费PDF全文
One effective method for suppression of coupling from guided optical modes into cladding modes in an optical fibre Bragg grating is to use cladding mode suppression fibre. In this specially engineered fibre, the grating is written into the core and the inner cladding, both of which are photosensitive. A theory is presented in this paper to analyse the spectral characteristics of this kind of gratings. A fibre Bragg grating was experimentally fabricated with this kind of photosensitive fibre (PS-RMS-50 from StockerYale). It is shown both theoretically and experimentally that such gratings exhibit strong suppression of the coupling between core mode and cladding mode. The experimental result is in good agreement with the theoretical analysis. 相似文献
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光纤光栅的局域耦合模分析 总被引:1,自引:1,他引:0
本文运用矢量局域耦合理论分析了平均扰动折射率随Z轴变化的单模光纤光栅的纤芯模场分布、包层模场分布以及耦合系数,得到更为精确的光栅光谱特性.并分别计算了布喇格光栅和长周期光纤光栅在平均扰动折射率在Z轴有扰动时的光谱特性图.从而得出平均折射率随Z轴变化对光谱特性的危害性,并提出了解决方法. 相似文献
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Jong Hoon Lim Gun Lim Kyung Shik Lee Jeong Hwan Song Yun Kyung Oh Sun Tae Jung Tae Il Kim 《Fiber and Integrated Optics》2005,24(2):73-82
We fabricated Bragg gratings in planar lightwave circuits and investigated their growth characteristics. The refractive index modulation of the gratings grew in the PLC with total fluence F by the power law δ n = AFB with A = 8.6 ± 0.9 × 10-8 and B = 1.47 ± 0.02. The PLC gratings as external reflectors for ECLs were controlled reasonably well by adjusting the writing conditions based on the power law and the coupled mode theory. The properties of fabricated PLC gratings were closely matched to the design parameters of the PLC grating. The single longitudinal mode oscillations of the ECLs were also demonstrated at 1309.5 nm and 1550.5 nm. 相似文献
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Peter Kozma Andras Hamori Kaspar Cottier Sandor Kurunczi Robert Horvath 《Applied physics. B, Lasers and optics》2009,97(1):5-8
An interferometric sensor based on gratings on a planar waveguide is introduced. The device combines the advantages of known
interference-based waveguide sensors with the simplicity of grating couplers. In the presented configuration, two parallel
and coherent light beams, laterally separated in the direction of mode propagation, are coupled into a planar waveguide through
a grating. One of the coupled beams is phase modulated using a periodically relaxing liquid crystal modulator, resulting in
a time varying intensity signal at the end face of the waveguide. Refractive index changes within the waveguide section between
the two coupling regions are monitored by observing characteristic changes in the intensity signal. 相似文献
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Yanhua Luo Zengchang Li Ru Chen Qijin Zhang Gangding Peng Gang Zou Bing Zhu 《Optics Communications》2009,282(12):2348-2353
Based on the photoinduced birefringence in azo materials, the model of the birefringent long period fiber gratings (BLPFGs) has been proposed and the transmission of such birefringent fiber gratings was further simulated by the coupled mode theory. In order to obtain the optimum condition for making birefringent azopolymer optical fiber (APOF) gratings the photoinduced birefringence of azo dye and methyl methacrylate (MMA) copolymers was systematically studied. After photosensitivity study of azo samples, using Teflon technique, azo dye containing single mode polymer optical fiber (POF) was fabricated. Finally, BLPFGs can be fabricated in azopolymer fiber using polarized 532 nm laser. A 120 μm LPFG with a 50% duty cycle has been successfully written within the core of the fiber with 532 nm laser by an amplitude mask method. Under polarized microphotography, the grating was observed when the optical axis was set at 45° with the direction of the first polarizing lens of the polarization microscope. 相似文献
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Kuiru Wang Gong Chen Binbin Yan Xinzhu Sang Jielin Cheng 《Optics Communications》2011,284(7):2012-2017
We introduce both concave and convex rectangular apodizations in the middle of fiber Bragg gratings to achieve slow light. Based on the nonlinear coupled mode equations (NLCMEs), the transmission characteristics of grating solitons in rectangle-apodized gratings are numerically simulated and analyzed. The rectangular apodization can change the grating coupling coefficient to give rise to slow and capture the solitons in gratings. The effects of the soliton energy parameters, the width of rectangular apodization and the variation of the coupling coefficient on the soliton transmission are presented. The results show that, the velocity of solitons can be slowed down, and the capability to capture a soliton depends on the energy of input solitons, coupling coefficient, and the rectangular width. Two kinds of soliton capture methods are proposed and compared with each other. 相似文献
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利用傅里叶模式理论分析了TE波自准直角入射的使用条件下,多层介质膜光栅的光栅区和多层膜区电场分布的特点.分别讨论了HfO2和SiO2为顶层光栅材料时,光栅结构参数对光栅脊峰值电场的影响,结果表明,对于不同膜厚的顶层材料,存在一个最佳膜厚度,使光栅脊峰值电场最小,并且当膜厚增大时,设计大高宽比的光栅可以降低该电场峰值.最后,在大角度条件下使用多层膜光栅也可以降低光栅脊处的峰值电场.
关键词:
衍射光学
多层介质膜光栅
模式理论
损伤阈值 相似文献
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偏振片在诸多光学系统中有着重要的应用。亚波长介质光栅可用作正入射偏振片,在高能激光系统中有着广泛的应用前景。为了探究波长为1 064 nm的纳秒脉冲激光对于亚波长全介质光栅的诱导损伤特性,使用了粒子群优化算法结合严格耦合波分析设计了光栅的几何参数,计算表明亚波长光栅偏振片在入射光波长1 064 nm附近带宽0.5 nm内,平均消光比为1 500。使用了紫外曝光配合离子束刻蚀的工艺制备了HfO2光栅,并对其纳秒脉冲激光损伤阈值进行了测试。测试结果表明S光损伤阈值约为P光损伤阈值的5倍,且都大于5 J/cm2。结果表明亚波长全介质光栅偏振片可广泛用于正入射激光系统中。 相似文献
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Cladding-mode-assisted recouplings in concatenated long-period and fiber Bragg gratings 总被引:1,自引:0,他引:1
We investigate new types of mode recouplings in a concatenated grating structure comprising a long-period grating and a fiber Bragg grating. It is demonstrated that the light coupled out to the cladding mode by one of these gratings can be recoupled back to the guided mode by the other grating. Theoretical analysis based on the coupled-mode theory is presented, together with experimental results. 相似文献
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An embedded metal-wire nanograting is designed and fabricated for the first time to our knowledge. This artificial material could be used as a broadband polarizing beam splitter to reflect s-polarized light and transmit p-polarized light. An upper-cladding layer of the same material as the gratings is deposited on the ridge of the gratings, whereas the metal wire is deposited in the grating trenches. This embedded structure makes the grating more firm in its applications. High polarization efficiency and low insertion loss with a broad wavelength range (900-1700 nm) and a wide angular tolerance are obtained by optimization of the designed structure. 相似文献