共查询到20条相似文献,搜索用时 140 毫秒
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在1.523μm波长He-Ne激光,对于Z切Ti扩散LiNbO_3光波导及其带有金属包覆/介质缓冲层的偏振器结构,理论上计算了单模波导的工艺参数和基模的吸收损耗系数.文中用TM_0模的共振吸收效应,在1.5μm波长首次研制成Ti:LiNbO_3光波导TE_0模偏振器.当器件长度为2mm和9mm时,其消光比分别为20dB和25dB. 相似文献
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采用静电近似理论计算了Ag纳米棒阵列在不同偏振光入射下的消光光谱。当入射光偏振方向平行于纳米棒长轴时会激发表面等离激元纵向振动模式,而当入射光偏振方向垂直于纳米棒长轴时会激发表面等离激元横向振动模式。基于两种模式共振波长的不同,采用Ag纳米棒阵列可以用来设计高性能的表面等离激元微型偏振器。Ag纳米棒阵列的偏振性能在纵向共振波长明显优于在横向共振波长,通过调节纳米棒的纵横比可以对纵向模式的共振峰位进行大范围调控。结果表明这种微型偏振器所适用的波长能够通过纳米棒的纵横比在可见到近红外波段范围内调控,而消光比和插入损耗能够通过纳米棒的直径和长度实现调控。 相似文献
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飞秒激光光刻是一种灵活的三维光子器件制作方法。由于铽镓石榴石具有法拉第效应,具有广泛的应用,利用中心波长为800nm,重复频率为1kHz的飞秒激光,在磁致旋光晶体铽镓石榴石中刻写了双线型和压低圆包层两种光波导,重构了激光诱导折射率改变的分布和测试了光波导的传输损耗。双线型波导具有偏振依赖的导光特性,圆包层波导则不存在偏振依赖的导光特性。对于双线型波导,横电(TE)模和横磁(TM)模相位完全失配,在外加磁场下,导模的偏振面不会发生旋转,光刻的圆包层波导的导模的偏振面能够发生磁致旋转。铽镓石榴石中的双线型和圆包层波导可以作为波导偏振器和磁旋光器件,在集成光学上有潜在的应用价值。 相似文献
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研究了使用钛宝石放大器输出的重复频率为50kHz、中心波长为775nm、脉冲宽度为160fs的超快激光在掺镱钇铝石榴石(Yb…YAG)中刻写双线型光波导的过程。发现了波导具有偏振导光现象,偏振态平行于双线方向的激光可以导通,偏振态垂直于双线方向的激光不能导通。详细分析了双线间距、刻写速度和激光脉冲能量对波导形成的影响,在双线间距为30μm、刻写速度为400μm/s、脉冲能量为5.0μJ的条件下写入的光波导导光特性良好。利用近场模重建了该波导折射率二维分布,波导区域折射率相对于基质改变量的最大值为1.8×10-4,且该波导在940nm半导体激光抽运激励下,获得了1030.5nm的连续激光输出,激光功率为4.7mW。 相似文献
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利用中心波长1 028nm、重复频率50kHz、脉冲宽度220fs的超短脉冲激光在掺Nd~(3+)光热敏折变玻璃中刻写双线型和压低包层管状波导.研究了激光功率、波导双线间距、管状波导直径对近场模式的影响,得到了两组导光模式较优的波导.利用波导的近场模式强度分布重构了其折射率分布图,得到两类波导最大的折射率增加量分别为+7.0×10~(-4)和+5.5×10~(-4).利用散射法测得双线型波导的传输损耗为1.29dB/cm;通过测量插入损耗得到压低包层管状波导的传输损耗小于1.95dB/cm.利用飞秒激光在掺Nd~(3+)光热敏折变玻璃中直接写入光波导,在集成光学器件上具有广阔的应用前景. 相似文献
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《光学学报》2015,(4)
利用重复频率为1 k Hz,中心波长为800 nm,脉冲宽度为120 fs的超短脉冲激光在掺Er3+"无水"氟碲酸盐玻璃中利用狭缝整形技术横向刻写了I类和压低圆包层波导。在对波导刻写参数进行系统研究后,得到了两组导光模式较优的波导。利用波导的近场模式强度分布重构了其折射率分布图,得到两类波导最大的折射率增加量分别为1×10-4和1.9×10-4。用散射法测试了I类波导的传输损耗为1.04 d B/cm;通过测量插入损耗得到压低圆包层波导的传输损耗小于1.88 d B/cm。因此,利用飞秒激光在掺Er3+"无水"氟碲酸盐玻璃中刻写的光波导,在集成激光光源制作方面具有很好的应用前景。 相似文献
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基于圆波导TE11模的模式简并特性和微波在椭圆波导中传输两个正交TE11模式相速不同的性质,研制了一种带有椭圆波导结构的圆波导TE11模圆极化器。该圆极化器通过圆波导到椭圆波导的过渡段,将输入的线极化TE11模式分成两个等幅、正交的TE11模,然后调整椭圆波导长度,使得两个正交的TE11模式的相位差为90°,实现了TE11模式微波线极化到圆极化的转换。利用时域有限差分软件优化设计了该圆极化器,并按照优化的结构尺寸加工了一套实验装置进行了实验测试,测试结果表明:在工作频率9~10 GHz范围内,该圆极化器轴比小于1 dB,驻波比小于1.1,且功率容量大于1.6 GW。 相似文献
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A compact fiber polarizer is demonstrated by the filling of selected air holes of a hollow-core photonic crystal fiber (PCF) with a liquid. The liquid-filling results in an asymmetric waveguide structure, leading to a large polarization dependent loss. A 6 mm long ethanol-filled PCF exhibits a polarization extinction ratio of ~18 dB over a wavelength range from 1480 nm to 1600 nm. 相似文献
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A. M. Zheltikov 《JETP Letters》2004,80(6):389-392
Waveguide regimes of nonlinear-optical interactions allow a reduction of quantum noise in spectra of coherent Raman scattering (CRS). We will find the optimal waveguide length providing the maximum quantum limit for the signal-to-noise ratio in waveguide CRS and assess this ratio for laser intensities right below the optical breakdown threshold. This analysis shows that the quantum-limit signal-to-noise ratio of coherent femtosecond CRS spectroscopy of the gas phase can be increased in the waveguide regime by more than four orders of magnitude relative to the regime of tight focusing. 相似文献
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Hongyun Chen Xianfeng Chen Yishuai Zhang Yuxing Xia 《Applied physics. B, Lasers and optics》2007,89(1):25-28
We demonstrate a 1×4 waveguide array produced by an IR femtosecond laser in z-cut lithium niobate (LiNbO3). The polarization dependence of light coupling in this waveguide structure is experimentally investigated. The coupling
constants of the waveguide array are obtained by measuring the ratio of output power of each waveguide for extraordinary rays
and ordinary rays, and the variation of coupled power in each waveguide as a function of the waveguide length are demonstrated.
PACS 42.65.Re; 77.84.Dy; 42.82.Et 相似文献
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Renjie Zhang Zhigang Cao Shenglai Zhen Jun Zhu Renzhu Liu 《Optics Communications》2007,274(2):392-395
A novel configuration of fiber laser with frequency modulation is presented. Frequency modulation, stable polarization state and narrow linewidth are realized by using the waveguide phase modulator, polarization maintaining devices and saturable absorber. It is shown that the laser output reaches 23 mW, linewidth is less than 1 kHz, polarization extinction ratio is higher than 20 dB and maximum value of frequency deviation can reach 7.5 MHz. 相似文献
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Xiaoyang Guo Yi Xu Yanyan Li Xiao Zou Xiaoming Lu Cheng Wang Yuxin Leng Ruxin Li 《Applied physics. B, Lasers and optics》2014,117(3):973-978
A high-temporal contrast femtosecond Stokes pulse near 1,053 nm is obtained simply without polarizer extinction ratio limitation based on the stimulated Raman frequency shift process in ethanol with an 800-nm femtosecond Ti:sapphire laser as a pump source. By optimizing the incident pump pulse chirp and the ethanol Raman cell length, a clean Stokes pulse near 1,053 nm with a maximum energy of 0.24 mJ is obtained with ~7.5 % conversion efficiency and 0.8 % (rms) energy fluctuation. Compared with the incident pump pulse, the temporal contrast of the Stokes pulse is improved by at least approximately three orders of magnitude. 相似文献
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Coherent linking of periodic nano-ripples on a ZnO crystal surface induced by femtosecond laser pulses 总被引:1,自引:0,他引:1
X. D. Guo R. X. Li Y. Hang Z. Z. Xu B. K. Yu Y. Dai B. Lu X. W. Sun 《Applied Physics A: Materials Science & Processing》2009,94(2):423-426
We demonstrate the coherent linking of periodic nano-ripples formed on the surface of ZnO crystals induced by femtosecond
laser pulses. By adjusting the distance between two laser scanning zones, the periodic nano-ripples induced by two separated
laser writing processes can be coherently linked and the ZnO nanograting with much longer grooves is therefore produced. The
length limitation of this kind of nanograting previously set by the laser focus size is thus overcome. The micro-Raman mapping
technique is used to evaluate the quality of coherent linking, and the underlying physics is discussed. The demonstrated scheme
is promising for producing large-size self-organized nanogratings induced by femtosecond laser pulses. 相似文献
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The high dependence of polarization resolved laser-induced breakdown spectroscopy on experimental conditions 下载免费PDF全文
It is shown that the continuum emission produced by an Al alloy ablated by femtosecond laser pulses is much more polarized than the characteristic lines of elements. A Glan-Thomson polarizer is used in the laser-induced breakdown spectroscopy experiment to investigate the polarization effect. The use of the polarizer at its minimal transmission increases the signal-to-noise ratio. The effects of angle of detection, focal position, and pulse energy on the signal-to-noise ratio are also studied. 相似文献
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Tightly focused, linearly polarized, femtosecond laser radiation can produce highly birefringent nanograting structures inside fused silica glass. Here we report that when the polarization direction of the femtosecond light is changed, old nanogratings are erased and simultaneously replaced with new ones whose orientation is solely determined by the polarization of the rewrite beam. We also show that these volume nanogratings can be rewritten 1000 times with little degradation in their quality. 相似文献