Design and Simulation of Broadband IR integrated Waveguide Amplifiers with Long - Period Waveguide Grating Filter

A novel broadband IR integrated Er-Yb codoped phosphate glass waveguide amplifier with a long-period waveguide grating is proposed. The long-period waveguide grating, which is used as a gain equalizer, is directly fabricated in the waveguide. The amplifier model is based on propagation and population-rate equations and includes both uniform and pair-induced up-conversion mechanisms. It is solved numerically by combining overlapping integral and Runge-Kutta(RK) algorithm. The intrinsical gain spectrum of the proposed amplifier is obtained by solving a set of rate and power propagation equations and, the deleterious gain peaking is reduced by the long-period waveguide grating filter. The effects of transmission spectrum of the proposed long-period grating on flattening gain are discussed. An average gain  ~ 20dB between 1532 nm and 1565 nm with gain difference of  < 3dB is achieved.     

Lithium–Niobate Channel Waveguide for the Realization of Long-Period Gratings

We propose a special lithium-niobate (LiNbO₃) single-mode waveguide for the realization of long-period gratings, which consists of a channel core embedded in a thin slab cladding. We fabricated the waveguide on a z-cut LiNbO₃ substrate with a two-step proton-exchange process and demonstrated its suitability for grating application with a number of removable photoresist long-period gratings deposited on the waveguide surface. The waveguide fabrication process and the LiNbO₃ waveguide structure could be further explored for the development of electrooptic gratings for high-speed applications.     

Realization of Long-Period Corrugated Grating in Silica-on-Silicon-Based Channel Waveguide

Long-period corrugated grating in silica-on-silicon-based channel waveguide is realized by making periodic corrugation on top of a relatively high-indexed (contrast ap.8%) Ge-doped silica waveguide, which is sandwiched between undoped silica undercladding and boro-phospho-silicate-glass overcladding layers. Resonance wavelength of the 15-mm-long grating is found at ~1581 nm, having negligible polarization dependency at room temperature, with a grating strength of ~11 dB and 3-dB bandwidth of 7 nm. The temperature characteristic of the grating is also investigated, which is found to be similar to that of the long-period fiber grating. This device has significant potential for various integrated-optic communication and sensing applications.     

Fabrication and characterization of annealed proton exchanged long period waveguide grating in x-cut LiNbO3

In this paper, a long-period waveguide grating was fabricated in x-cut lithium niobate substrate by patterned annealed proton exchange waveguide fabrication process. The waveguide mode characteristic was evaluated using a charge-coupled device (CCD) camera. It shows that the waveguide is single mode transmission at a wavelength of 1 550 nm. The transmission spectra of the long period waveguide gratings were measured by optical spectrum analyzer (OSA) and show an extinction ratio of ~17 dB and a 3 dB bandwidth of ~10 nm at the resonant wavelength. The resonant wavelength moves toward to the long wavelength direction as the waveguide width-difference increases in the same period, and also shifts toward to the long wavelength direction with the increase of the period in the case of the same waveguide width-difference. The method of fabricating a long period waveguide grating based on a patterned annealed proton exchange technique simplifies the fabrication process, and at the same time, reduces the fabrication cost.     

Interrogation of a Long-Period Grating Sensor by a Thermally Tunable Arrayed Waveguide Grating

An interrogation technique for a long-period grating (LPG) sensor is studied theoretically and experimentally. By employing a thermally tunable arrayed waveguide grating (AWG), the center wavelength of the LPG sensor is successfully measured using the linear temperature dependence of the AWG transmission wavelengths. Initial results show that the proposed interrogation technique can provide a resolution of 1 pm and interrogation range of 25 nm. Furthermore, this technique has the potential of being packaged into a low-cost and compact-size device.      

基于表面等离子波耦合的流体波导光栅耦合器

提出了一种由金属光栅和流体光波导结构组成的,基于表面等离子波耦合的光栅耦合器。利用光栅的衍射效应,将金属光栅与介质分界面之间产生的表面等离子波耦合到流体光波导中,并且能够沿着流体光波导稳定地向前传播。通过采用基于有限时域差分算法的FDTD Solutions软件对光栅耦合器进行了参数优化及特性分析,通过优化使该结构在650 nm波长下的耦合效率达到56%。此外,由于该结构对TE偏振光和TM偏振光的选择比达到70∶1,因此具有偏振器的功能。同时由于TE偏振光耦合频谱的频带宽度仅为20 nm,该结构还具有窄带滤波的作用。此外,还研究了光栅结构参数、入射角以及流体折射率对耦合频谱的影响。     

SOI亚微米波导光栅的设计与制作

报道了SOI基亚微米小尺寸波导光栅器件的设计、制作与测试结果。提出了波导与光栅同步制作的方案,避免了套刻,节约了成本。实验中采用电子束光刻(EBL)、感应耦合等离子体(ICP)刻蚀等先进半导体工艺技术,结合图形补偿等技术手段,完成了亚微米波导光栅的制作。光栅周期为350nm,占空比16∶19。采用该光栅做反射镜,制作了法布里-珀罗(F-P)谐振腔,经测试得到了与模拟相吻合的结果,峰谷比达到11dB。     

Design and Simulation of a Narrow Passband Electro-Optical Tunable Filter with Band-pass and Band-rejection Output

An electro-optical tunable filter comprised of two paralleled identical long-period waveguide gratings is proposed in this paper. The filter has one input port and two separate output ports, outputting band-pass and band-rejection light respectively. Using poled electro-optical polymer material to fabricate its waveguide cores enable the filter’s tuning speed to approach nanosecond order. With the aid of long-period waveguide gratings, the tuning range of the filter is Λ times larger than the conventional electro-optical filters. We built up a model to design and simulate the proposed tunable optical filter. We investigate the relationship between the parameters of the long-period waveguide grating and the characteristics of the tunable filter, such as tuning range and FWHM. The simulation results show that the tunable optical filter can realize high-speed tuning in the wavelength range of 1530 nm to 1560 nm, and the FWHM width can reach 0.8 nm. Compared with the conventional optical filters, the results show that a high-speed widely tunable optical filter with narrow pass band can be achieved.     

Polymer waveguide notch filter using two stacked thermooptic long-period gratings

A polymer waveguide notch filter using two stacked thermooptic long-period gratings is proposed. It is a long-period waveguide grating whose transmission spectrum can be dynamically controlled. Thermooptic index perturbation, i.e., grating is temporarily induced by two groups of periodic heaters stacked vertically on the filter surface. The periods of the two groups are determined such that two different resonance bands are generated in the spectrum by the respective groups. Thus, the overall spectrum may be actively shaped by controlling the individual power applied to the two groups. Its feasibility is demonstrated experimentally by fabricating it with thermocurable polymers.     

Waveguide grating filters for dispersion compensation and pulsecompression

Dispersion compensation and pulse compression are theoretically demonstrated using aperiodic waveguide gratings. The gratings are designed to have both a flat amplitude and a quadratic phase response over the pulse bandwidth. This results in nearly transform-limited compressed pulses. The appropriate waveguide grating parameters are obtained by applying the Gel'fand-Levitan-Marchenko inverse scattering method to the coupled mode equations which describe propagation. The technique is illustrated by designing an aperiodic grating which compresses a 60-ps pulse by a factor of three. Limitations and possible extensions of the general method are discussed     

钛扩散LiNbO_3晶体光波导长周期光栅

设计了一种钛扩散铌酸锂(LiNbO_3)晶体光波导结构,并在该基础上制作了长周期光栅.使用两步钛扩散方法在Z切LiNbO_3基片上制造了波导,它包括一个单模芯层和一个平面包层,之后用光刻胶光栅置于波导表面.实验证明用这种结构设计长周期波导光栅是可行的.对光波导制造工艺和波导结构的深入研究,为制作高速电光调制型光栅提供技术基础.     

基于SOI材料的偏振不敏感的阵列波导光栅

阵列波导光栅(AWG Arrayed Waveguide Grating)是实现多通道密集波分复用(DWDM Dense Wavelength Division Multiplexing)光网络的理想器件,偏振敏感性是它的一个重要性能指标。本文针对SOI材料的阵列波导光栅,分析了如何采用特殊的波导结构来减小它的偏振相关性,并对16通道、间隔为0．8nm的AWG解复用器进行了计算,结果表明其偏振敏感性低于0．06nm。     

基于长周期光栅的宽带磷酸盐玻璃波导放大器

提出一种基于长周期波导光栅的宽带集成Er-Yb掺杂磷酸盐玻璃集成波导放大器,其中增益平坦光栅滤波器直接刻蚀在有源波导上.放大器模型建立在考虑了上转换之后的传输与速率方程基础上,利用重叠积分与龙格-库塔相结合的方法进行求解.放大器的本征增益谱通过求解重叠积分龙格-库塔方程得到,放大器的有害增益峰由长周期波导光栅滤波器来消除.讨论了长周期波导光栅透射谱对放大器增益平坦的影响.数值计算结果表明,在1 532～1 565 nm范围内,放大器的平均增益约为20 dB,增益抖动小于3 dB.研究结果表明,该结构可有效地消除本征增益谱中的峰值增益,提高放大器的增益平坦带宽.     

Bandstop Filter Design Using a Dielectric Waveguide Grating

Precision design techniques are obtained for dieletric waveguide (DW) bandstop filters with bandwidths up into the 5-10-percent range. Dielectric waveguide bandstop filters are realized in the form of a grating in the DW image guide which utilizes notches of varying depth and length. The grating is designed from a transmission-line prototype which has a prescribed stopband and also prescribed Chebyshev passbands. An approximate synthesis procedure for such prototypes is presented. Design data for grating notches were obtained from tests on uniform gratings, while DW dispersion is compensated for by calculations based on the "effective dielectric constant" method. Excellent agreement between computed and measured attenuation response is obtained. Two such grating structures used with loads on one end and a 3-dB coupler can be used to form a bandpass filter.     

Distributed feedback surface-emitting laser with air/semiconductor gratings embedded by mass-transport assisted wafer fusion technique

We report on a distributed feedback InGaAsP MQW laser with air/semiconductor gratings embedded by wafer-fusion technique with the assistance of mass-transport phenomenon for the first time. The air/semiconductor gratings with 0.4-/spl mu/m period and 0.2-/spl mu/m depth are successfully fabricated inside the device, and a single longitudinal mode oscillation at about 1.28 /spl mu/m is demonstrated under pulsed condition at room temperature. The threshold current density is estimated to be about 1.4 kA/cm/sup 2/. It is also shown that the device has a surface-emitting function since it has a low loss multiquantum-well waveguide with grating output coupler.     

非互易波导光栅的滤波特性与应用

根据磁光材料的非互易特性和波导光栅的滤波特性,介绍了一种磁光波导光栅的非互易滤波特性及其应用.该磁光波导光栅采用法拉第旋转系数为4800°/cm的掺铈钇铁石榴石(Ce:YIG)材料、单模的脊型补偿墙截面结构和cosine型变迹光栅结构的设计.利用有限差分法和等效折射率法模拟该磁光波导光栅非互易效应的大小,同时结合耦合模理论和转移矩阵法对该磁光波导光栅的非互易滤波特性进行分析.结果表明,对于TE模和1550 nm波段,该磁光波导光栅正反向传输的中心波长偏移0.8 nm,带宽0.4 nm(-20 dB).这种非互易滤波特性可以用来实现波长选择光隔离器和光分插复用器(OADM)等集成光学器件.     

长周期光纤光栅波导色散因子和有效折射率热光系数的测量

对串联的长周期光纤光栅(CLPFG)的透射谱特性进行了理论分析和实验研究。分析表明,长周期光纤光栅中纤芯模和包层模之间的马赫曾德尔干涉效应导致在长周期光纤光栅谐振峰内的梳状滤波结构特性;其峰值位置和峰间距同串联区光纤的长度以及光纤的波导色散因子有关。测量了长周期光纤光栅的透射谱,并研究了其温度特性。根据测量数据,得到对应于1554 nm波长处,所用单模光纤HE14模的波导色散因子γ为0.874;纤芯/包层有效折射率差的热光系数为4.8×10-5℃-1。并对这一测试方法和结果,以及长周期光纤光栅的应用进行了讨论。     

离子束辅助沉积真空镀膜技术制备阵列波导光栅波导材料

采用离子束辅助沉积(IBAD)真空镀膜技术制备阵列波导光栅(AWG)波导材料。以固体石英玻璃材料作为衬底,采用离子束辅助沉积真空镀膜制备SiO2膜层,以实现偏振不敏感的阵列波导光栅。实验表明器件的偏振相关性大大改善,其双折射B约为1.4077×10-5,远小于二氧化硅-硅基波导结构阵列波导光栅的双折射B=2×10-4。器件的热稳定性也得以改善,当工作环境的温度变化范围为-10~70℃时,采用此方法研制的阵列波导光栅最大波长漂移为1.144 nm,小于普通的二氧化硅-硅基波导结构阵列波导光栅的波长漂移1.368 nm。     

Fabrication and Evaluation of Bragg Gratings on Optimally Designed Silicon-on-Insulator Rib Waveguides Using Electron-Beam Lithography

报道了一种用电子束曝光的方法在绝缘体上硅的脊状光波导上制做布拉格光栅的技术.考虑到实际的光子学集成的应用,讨论了这个带有布拉格光栅的脊状光波导的优化设计,给出了该布拉格光栅的测试和理论模拟结果.通过薄化绝缘体上硅的波导层的厚度和光栅的深腐蚀加工,获得了高达30cm-1的光栅耦合系数.     

用电子束曝光方法在优化设计的绝缘体上硅脊状波导上实现布拉格光栅的制作和评价

报道了一种用电子束曝光的方法在绝缘体上硅的脊状光波导上制做布拉格光栅的技术.考虑到实际的光子学集成的应用,讨论了这个带有布拉格光栅的脊状光波导的优化设计,给出了该布拉格光栅的测试和理论模拟结果.通过薄化绝缘体上硅的波导层的厚度和光栅的深腐蚀加工,获得了高达30cm-1的光栅耦合系数.