共查询到20条相似文献,搜索用时 31 毫秒
1.
The method of parameter optimization of combined structures, which consist of a dielectric grating and a metallic or multilayer dielectric mirror, was proposed. It is based on the use of the waveguide properties of the combined diffraction grating. Its main advantage lies in the possibility of determining the optimum parameters of the combined grating without solving the diffraction problem. 相似文献
2.
Chun-Ting Lin 《Optics Communications》2011,284(1):195-200
An athermal metal-free planar waveguide concave grating demultiplexer is proposed. We designed the dielectric mirror at the grating facet instead of coating with the metal on the back wall of the grating facet. The transfer-matrix method is introduced to design the dielectric mirror and the reflectance spectral responses of the 2D waveguide structure are simulated using the FDTD software (RSoft, Inc.). To reduce the temperature sensitivity of the device, the three-focal-point method is introduced. We use the design example to show the high-reflectance bandwidth of the dielectric mirror. The fabrication errors are also taken into consideration. By using the numerical model of the scalar diffraction theory, the flat-top spectral responses of the channels are simulated. 相似文献
3.
Study on guided-mode resonance characteristic of multilayer dielectric grating with broadband and wide using-angle
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Guided-mode resonance in a diffraction band of multilayer
dielectric gratings may lead to a catastrophic result in laser
system, especially in the ultrashort pulse laser system, so the
inhibition of guided-mode resonance is very important. In this paper
the characteristics of guided-mode resonance in multilayer
dielectric grating are studied with the aim of better understanding
the physical process of guided-mode resonance and designing a
broadband multilayer dielectric grating with no guided-mode
resonance. By employing waveguide theory, all guided-wave modes
appearing in multilayer dielectric grating are found, and the
incident conditions, separately, corresponding to each guided-wave
mode are also obtained. The electric field enhancement in multilayer
dielectric grating is shown obviously. Furthermore, from the
detailed analyses on the guided-mode resonance conditions, it is
found that the reduction of grating period would effectively avoid
the appearing of guided-mode resonance. And the expressions for
calculating maximum periods, which ensure that no guided-mode
resonance occurs in the requiring broad angle or wavelength range,
are first reported. The above results calculated by waveguide theory
and Fourier mode method are compared wit each other, and they are
coincident completely. Moreover, the method that relies on waveguide
theory is more helpful for understanding the guided-mode resonance
excited process and analyzing how each parameter affects the
characteristic of guided-mode resonance. Therefore, the effects of
multilayer dielectric grating parameters, such as period, fill
factor, thickness of grating layer, {\it et al.}, on the guided-mode
resonance characteristic are discussed in detail based on waveguide
theory, and some meaningful results are obtained. 相似文献
4.
Dielectric mirrors, which yield high-reflectances on grating facets, are proposed for the design of a planar waveguide concave grating. The transfer-matrix method is used to derive an expression for the reflectance of a series of air slots and high-index stacks. The FullWAVE software, a finite difference time-domain EM solver from R-Soft, is used to evaluate the loss of the resulting 2D waveguide grating. The simulation results show that the polarization-dependent loss (PDL) is below 0.25 dB when the proposed dielectric mirror is used. The influence of the width variation of the dielectric stack is also taken into account. 相似文献
5.
6.
Analysis of restriction factors of widening diffraction bandwidth of multilayer dielectric grating
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In order to design a multilayer dielectric grating with wide-bandwidth diffraction spectrum, the restriction factors of both the reflection bandwidth of multilayer dielectric high-reflectivity mirror and the guided-mode resonance phenomenon are studied in detail. The reflection characteristics of high-reflectivity mirror in zeroth and 1st transmitted diffraction orders are quantitatively evaluated. It is found that the reflection bandwidth of high-reflectivity mirror in 1st transmitted diffraction order, which determines the final diffraction bandwidth of multilayer dielectric grating, is evidently compressed. Furthermore, it is demonstrated that the reducing of grating period is an effective approach to the elimination of guided mode resonance over a required broad band range both spectrally and angularly. In addition, the expressions for calculating the maximum period ensuring no guided mode resonance in the required bandwidth are derived. Finally, two high-efficiency pulse-compression gratings with broad-band are presented. 相似文献
7.
Xu Zhang Yongqing HuangXiaomin Ren Hui HuangQi Wang 《Optics and Lasers in Engineering》2011,49(5):599-604
A new type of one-mirror inclined waveguide-grating photodetector, which combines a waveguide-grating filter and an inclined top mirror is proposed. Greatly improved spectral response is achieved by the integration of waveguide-grating into classical thin-film homogeneous layers. Comparison between the grating filter and Fabry-Perot filter demonstrates that this structure has two advantages over other photodetector devices. First, the inclined mirror can decouple the quantum efficiency from response speed and spectral response linewidth. Second, comparing the traditional photodetector with Fabry-Perot filter, this type of photodetector with the same materials requires significantly fewer layers while maintaining the same linewidth response, high peak efficiency and remarkably low sideband reflectivity. Thus, this type of photodetector device represents basic new optical features with a significant potential for practical applications. 相似文献
8.
A multilayer dielectric cylindrical mirror (MDCM) based on the one-dimensional omnidirectional reflection of a photonic crystal is presented. In this case, the refractive indices of the two materials are 1.6 (polystyrene) and 4.6 (tellurium), and the corresponding optimized thicknesses are 0.75a and 0.25a. A very high reflectance over a wide frequency range is observed. In this case, a is the lattice constant of the photonic crystal. In this band, the MDCM has good reflection and focal properties. Therefore, it is feasible to use the MDCM for integrated waveguide devices. As an example, an etched diffraction grating demultiplexer based on the MDCM is also proposed. Both the operational principle and design of the device are introduced. This provides a method for designing compact integrated waveguide devices. 相似文献
9.
A hybrid metallic mesh multilayer dielectric coating mirror has been developed for use as an output mirror for optically pumped far infrared lasers. The metallic mesh provides a high reflectance in the far infrared while the multilayer dielectric coating is chosen to provide a maximum reflectivity at the pump wavelength (10 μm). This hybrid mirror has increased the output power of a CH3F waveguide laser at 496 μm by a factor of 350 over that obtained with a hole coupling mirror. In addition, this mirror results in a far infrared output beam which has a minimum angular divergence limited only by the particular oscillating transverse waveguide mode (the EH11 mode for this experiment). 相似文献
10.
The present paper proposes a new grating concept by which a volume phase grating is placed on top of a dielectric mirror stack. Instead of using a multilayer dielectric grating, wherein the uppermost layer of a thin film mirror is etched to create the desired binary phase grating we suggest to have an upper grating layer of a lower density gelatin-based volume phase grating in either sol–gel or dichromated gelatin. The key benefit is the elimination of the etching step which is the limiting factor in the production of large aperture gratings. We have investigated designs for s- and p-polarization as well as the necessary chemistry that is needed to achieve the required index modulations. Damage testing on dichromated gelatin and aerogel was performed and diffraction efficiencies for various prototypes were measured. 相似文献
11.
12.
A method for lowering the sideband levels associated with the spectral response of resonant waveguide-grating filters is presented. With a TM-polarized incident wave near the Brewster angle, the filter sidebands are suppressed by application of a half-wavelength absentee waveguide layer and an arbitrary-thickness grating layer. Adjusting the thickness of the grating layer permits control of the filter linewidth without appreciably affecting the sideband features. To verify the theoretical prediction, we fabricated and tested a double-layer waveguide-grating filter. It exhibited a peak efficiency of 82.4%, with sideband reflection levels below 0.6%, over a 95-nm spectral range. 相似文献
13.
G Carpintero E Rouvalis K Lawniczuk M Fice CC Renaud XJ Leijtens EA Bente M Chitoui F Van Dijk AJ Seeds 《Optics letters》2012,37(17):3657-3659
We report the generation of a 95?GHz carrier frequency by optical heterodyning of two wavelengths from adjacent channels from an arrayed waveguide grating-based multiwavelength laser. The extended cavity structure of the device provides low phase noise and narrow optical linewidth, further enhanced by the intracavity filter effect of the arrayed waveguide grating. We demonstrate that the generated RF beat note, at 95?GHz, has a -3 dB linewidth of 250?kHz. To the best of our knowledge, this is the narrowest RF linewidth generated from a free-running dual-wavelength semiconductor laser. The device is realized as a photonic integrated circuit using active-passive integration technology, and fabricated on a multiproject wafer run, constituting a novel approach for a compact, low-cost dual-wavelength heterodyne source. 相似文献
14.
Motaghian Nezam SM 《Optics letters》2008,33(15):1741-1743
A compact high-speed tuning laser source is demonstrated in two different configurations using a polygonal mirror scanner without a telescope. It is shown that the filter configuration finesse increases by utilizing multiple reflections from the polygon facet(s) and grating illumination(s). Theoretically, the free spectral range (FSR), the instantaneous linewidth, and the finesse of each filter configuration are derived. For single grating illumination, the measured coherence length, FSR, and power were 2.8 mm, 184 nm, and 40 mW at the scanning frequency of 50 kHz, respectively. Coherence length, FSR, and power of the second laser configuration were 6.2 mm, 117 nm, and 35 mW, respectively. Finally, images of a human finger were acquired in vivo using two proposed swept-source configurations. 相似文献
15.
A new class of Fabry-Perot filters produced by a multilayer dielectric mirror deposited on top of a reflecting volume Bragg grating is described. The first fabricated prototype for the 852 nm region demonstrates a 30 pm bandwidth, 90+% transmission at resonance, and a good agreement with theoretical simulation. 相似文献
16.
Thermally fixed reflection gratings for infrared light in LiNbO(3):Ti:Fe channel waveguides 总被引:1,自引:0,他引:1
We present a narrow-bandwidth interference filter in an optical monomode LiNbO>(3):Ti:Fe channel waveguide operating in the infrared wavelength region around lambda = 1.55 microm . The filter consists of a thermally fixed refractive-index Bragg grating recorded with visible green light by use of a holographic technique. In a first approach we measure a reflectivity for the infrared light of 60% and a linewidth (FWHM) of 0.11 nm. 相似文献
17.
In order to implement a fiber-optic Fabry-Perot tunable filter with a simple configuration, a concave mirror is made at the end of the optical fiber. The concave mirror is fabricated by attaching a thin polycarbonate (PC) film on the fiber end, pressing the PC film with a fiber ball to form a dimple, and then depositing a multilayer dielectric mirror. The concave mirror aligned to the fiber core makes the cavity alignment easy with a simple alignment configuration. Because of the self-alignment function of this cavity, a small, reliable, and fast filter could be fabricated. 相似文献
18.
A tunable guided-mode resonant (GMR) reflection filter based on dielectric elastomer actuators (DEA) is designed. Simulating the characteristics of the filter with rigorous coupled wave analysis, it is shown that the resonant wavelength of the kind of GMR filter can be tuned from 1442.8 nm to 1644.6 nm by applying voltage on the dielectric elastomer actuators which changes the period of the grating layer of the GMR filter conveniently. Furthermore, there is an almost perfect linear relationship of resonant wavelength tuned and the period varied with negligible effect on the linewidth. 相似文献
19.
20.
基于啁啾脉冲放大技术的超短脉冲激光系统是提供超快、超强激光的重要途径,具有良好输出波形和高损伤阈值的多层介质膜脉冲宽度压缩光栅是获得高峰值功率脉冲激光的关键. 基于傅里叶谱变换方法和严格模式理论,分析了多层介质膜光栅(MDG)在超短脉冲作用下的光学特性. 结果表明,当MDG的反射带宽小于具有高斯分布的入射脉冲的频谱宽度时,-1级反射脉冲呈非对称高斯分布,其前沿出现振荡,并且-1级反射脉冲能量开始剧烈下降. 讨论了MDG结构参数对其反射带宽的影响. 分析了MDG与超短脉冲作用时的近场光分布,对提高其抗激光损
关键词:
脉冲压缩光栅
傅里叶谱变换
模式理论
损伤阈值 相似文献