A novel wavelength dispersive device with a dispersive element based on staircase-like straight and parallel arrayed waveguides

We propose a new type of arrayed waveguide grating (AWG) multiplexer/demultiplexer based on modified group refractive index. This device is composed by an array of straight and parallel waveguides of equal length and each waveguide consist of two sections with different width. The length of the two sections are changed from a waveguide to the adjacent one following a linear dependence resulting in a wavelength dispersive waveguide array. An example of the device design for silicon-on-insulator (SOI) platform is provided and numerical simulations have been carried out for various arrayed waveguide parameters. We demonstrate that the group index modification can be used for tailoring device dispersion properties, and that it can also result in new dispersion characteristics predicted numerically not observed in conventional AWGs. Additional advantages are that the demultiplexer does not necessarily require bending waveguide sections as in a conventional AWG (de)multiplexers, and thus yields highly compact devices with potentially very low insertion loss. Channel spacing of 1 nm have been predicted for sub-micron waveguides sizes. In this paper it is also proposed a novel wavefront converter based on waveguide array lens-like element with waveguides broadened sections. Numerical results for different input/output geometries are analized.     

Broadband filter using cladding profile linearly tapered long-period waveguide grating

A method to increase the bandwidth of long-period waveguide gratings (LPWGs) is proposed using linearly tapered cladding profile and large coupling constant. Compared to conventional uniform LPWG, the simulated 20-dB bandwidth of the designed chirped LPWG is enlarged by 14 times, from 0.9 nm to 12.8 nm. Besides, a chirped LPWG with the new structure is also fabricated, and bandwidth broadening effect is observed.     

System degradation due to phase error induced crosstalk in WDM optical networks employing arrayed waveguide grating multi/demultiplexer

The phase error induced crosstalk within arrayed waveguide gratings (AWG) have been investigated theoretically as well as simulation. For WDM system, a crosstalk level of −21.9 dB causes a power penalty of 1 dB for 64 channels and less than 0.5 dB for 16 channels and 32 channels, respectively. For crosstalk level of −30 dB and below, the power penalty is negligible. Crosstalk due to phase error also causes higher power penalty at higher bit rate. Bit rate of 10, 20 and 40 Gbits/s causes power penalty of 1 dB with crosstalk level of −41.5, −46.25 and −49 dB, respectively.     

32-channel arrayed waveguide grating multiplexer using low loss fluorinated polymer operating around 1550 nm

A 32 × 32 arrayed waveguide grating (AWG) multiplexer operating around the 1550 nm wavelength has been designed and fabricated using highly fluorinated polyethers. The propagation loss of the slab waveguide is about 0.3 dB/cm at 1550 nm wavelength. The channel spacing of the AWG multiplexer is 0.8 nm (100 GHz). The insertion loss of the multiplexer is 10.3-15.3 dB and the crosstalk is less than −20 dB.     

WDM-PON upstream transmission using Fabry–Perot laser diodes externally injected by polarization-insensitive spectrum-sliced supercontinuum pulses

We propose, a novel upstream transmission scheme for high speed wavelength division multiplexed passive optical networks. Upstream transmission at bit rate of 2.5 Gb/s was demonstrated using a Fabry–Perot (FP) laser diode (LD) externally injected by a spectrum-sliced polarization-insensitive supercontinuum pulse source, located at central office. The impact of Rayleigh backscattering on transmission performance is also investigated. The proposed scheme is expected to be cost-effective since low-cost FP LDs are used for light sources.     

Ring resonator with multimode waveguide turning-mirror couplers in InGaAsP-InP

Compact In_0.67Ga_0.33As_0.6P_0.4/In_0.71Ga_0.29As_0.74P_0.26 on InP single ring resonators incorporating 2 × 2 multimode interference (MMI) turning-mirror couplers with cross coupling factor of 0.15 have been demonstrated. The form of race tracks is a 15-degree arc of 260 μm radius joined with a 60-degree arc of 110 μm radius, and finished with another 15-degree arc of 260 μm radius. The MMI turning-mirror coupler of 128 μm in length is used in the single ring resonators, which correspond to free spectral ranges of 82 GHz. A contrast of 4 dB, a finesse of nearly 3 and full-width at half-maximum (FWHM) of 0.24 nm for the drop port have been achieved in this single ring resonator. From the experimental value T_max/T_min of 21 dB, the experiment coupling factor coincides with the simulation.     

A 32-channel 100 GHz wavelength division multiplexer by interleaving two silicon arrayed waveguide gratings

A 32-channel wavelength division multiplexer with 100 GHz spacing is designed and fabricated by interleaving two silicon arrayed waveguide gratings (AWGs). It has a parallel structure consisting of two silicon 16-channel AWGs with 200 GHz spacing and a Mach-Zehnder interferometer (MZI) with 200 GHz free spectral range. The 16 channels of one silicon AWG are interleaved with those of the other AWG in spectrum, but with an identical spacing of 200 GHz. For the composed wavelength division multiplexer, the experiment results reveal 32 wavelength channels in C-band, a wavelength spacing of 100 GHz, and a channel crosstalk lower than -15 dB.     

Multiband processing of multimode light: combining 3D photonic lanterns with waveguide Bragg gratings

The first demonstration of narrowband spectral filtering of multimode light on a 3D integrated photonic chip using photonic lanterns and waveguide Bragg gratings is reported. The photonic lanterns with multi‐notch waveguide Bragg gratings were fabricated using the femtosecond direct‐write technique in boro‐aluminosilicate glass (Corning, Eagle 2000). Transmission dips of up to 5 dB were measured in both photonic lanterns and reference single‐mode waveguides with 10.4‐mm‐long gratings. The result demonstrates efficient and symmetrical performance of each of the gratings in the photonic lantern. Such devices will be beneficial to space‐division multiplexed communication systems as well as for units for astronomical instrumentation for suppression of the atmospheric telluric emission from OH lines.     

A flattop PLC polymer waveguide interleaver based on folded two-stage-cascaded Y-junction Mach-Zehnder interferometers

We demonstrate realization of a flattop Y-Junction Planar Optical Waveguide Interleaver (YJPOWI) with a channel spacing of 100 GHz through a novel scheme of folded cascaded two-stage unbalanced Mach-Zehnder interferometers (MZI) fabricated on a polymer Planar Lightwave Circuit (PLC) platform. The characteristic 0.5 dB passbands of the interleaver centered at ITU wavelength grids at its two output ports were 50 and 45 GHz, respectively. The operating bandwidth of the device spanned the entire C band of a fiber amplifier and it is compact in size (1.3 × 1.4 cm²). In addition, the device is easy to fabricate and do not require any individual heater to trim its performance.     

掺半导体玻璃波导特性研究

利用离子交换技术制成了单模和多模掺CdSxSe_1-x半导体玻璃波导。通过对波导参数的测量得出这种波导的折射率剖面满足费米函数分布。同时,对这种K⁺—Na⁺离子交换技术得到的单模波导在0.5145μm波长下输入—输出功率的测量,观测到它的功率限制作用。并得到在Ar⁺激光0.5145μm波长下吸收系敲是4cm^-1。在这篇文章中,我们对波导的光功率限制起源于热效应进行了分析和讨论。     

Arrayed waveguide grating multiplexer with high thermal stability on silicon

In this paper, certain important parameters are optimized for a polymer/Si arrayed waveguide grating (AWG) multiplexer by using grating theory. A 32-channel multiplexer is designed and fabricated using newly synthesized fluorinated poly (ether ether ketone) with a high thermal stability. The measured wavelength channel spacing is 0.796 nm, and center wavelength and 3-dB bandwidth are 1548 nm and 0.3 nm, respectively.     

Low-crosstalk and low-loss waveguide crossings on InP with small dimensions

With the increasing scale of integration, resulting in a higher on-chip complexity, waveguide crossings with good performance are becoming increasingly important. Worst-case paths contain a high number of crossings, depending on the number of channels being processed, in switching matrices [11, multiwavelength add drop filters [2] (up to 151, and optical cross-connects [3]. Crossings with very low crosstalk and loss can be realized in fiber-matched waveguide structures as used in lithium niobate or silica-based technology [4,5]. In highly integrated semiconductor devices, crossings may contribute significantly to the loss and crosstalk performance. In this paper we present the results of a series of experiments for the design of high-performance semiconductor waveguide crossings.     

基于半导体光放大器的交叉增益调制效应实现2.5Gb/s归零码的全光波长变换

采用半导体光放大器的交叉增益调制进杆了2.SGb/s的归零码光脉冲的波长变换。向下波长变换间距大于20nm,向上波长变换间距大于10nm.对变换信号测量了接收机入纤功率和误码率的关系。对实验结果进行了分析,实验表明采用半导体光放大器的交叉增益调制效应对归者吗进行波长变换时存在着一些问题。     

Potential for size reduction of AlGaAs optical channel waveguide structures fabricated by focused ion beam implantation and oxidation

Optical channel waveguides formed by focused ion beam (FIB) implantation-induced mixing of AlGaAs multiple quantum well structures and subsequent oxidation of the mixed regions have the potential of significantly reducing the size of integrated photonic waveguide structures. Since FIB implantation is a direct write process characterized by nanoscale precision, we suggest its use for forming channel waveguides having nanoscale (submicrometer) widths. Calculations presented for such channel waveguides show reductions in size by at least an order of magnitude are possible for directional couplers and other structures involving curved channel waveguide sections. Such size reductions would allow the realization of significantly higher levels of device integration than are now currently possible.     

S波段宽带光纤喇曼放大器研究

在PTDS(Photonic Transmission Design Suite)仿真平台上,用3个泵浦源的RFA实现了S波段的增益平坦,同时对泵浦光与信号光,信号光与信号光,泵浦光与泵浦光之间的相互作用以及RFA的噪声特性进行了研究.     

Impact of a Post-OTDM-Demultiplexing Optical Filter on Dense OOK OTDM-WDM Transmission

The impact of a post-OTDM-demultiplexing optical filter on the performance of dense on-off keying (OOK) optical time division multiplexing (OTDM)—wavelength division multiplexing (WDM) systems was studied. For return-to-zero (RZ) modulation, it was found that the additional filter working in a double-tier filter configuration did not offer any significant improvements to performance when the signal pulse width is optimized. Improvements generally increase only when the signal pulse width deviates from its optimal value and only for low spectral densities. For ideal non-return-to-zero (NRZ) modulation, however, significant improvements of around 1 dB are obtained using the double-tier configuration over a large range of spectral densities.     

Stress reduction in planar waveguide using polymer top layer

Planar optical waveguides consisting of layers from different materials created at elevated temperatures usually exhibit substantial stresses. By controlling the layer thickness of polymeric top layer on planar waveguide structures, it is possible to use very thin layers for stress compensation, significantly reducing required deposition times. It is possible to reduce birefringence within planar device by controlling top polymer layer thickness with thermal expansion coefficient greater than silica or PMMA.     

钛扩散LiNbO3单模波导场分布

给出了 Ti 扩散 LiNbO₃条波导任意阶导模场分布的近似解,通过逐点近似法确定待定常数,分析了它的物理意义,也给出了导模的传播常数和有效折射率的解析式,与变分法相比,这种方法物理概念明确,计算量小,寻优简单,为集成光学的设计提供了一种计算精度较高的计算方法.     

Optimization of reflection spectra for phase-only sampled fiber Bragg gratings

In this paper, the reflection spectra of a phase-only sampled fiber Bragg grating is obtained by optimizing its phase profile. The standard simulated annealing method is improved for optimization, and superior phase profiles which contain as few segments as possible per sampling period are obtained for 8, 16 and 32 identical channels. As very well known, increased number of WDM channels results in higher grating length and refractive index modulation amplitude. It is observed that application of these phase profiles limits the increases in both of these parameters considerably.     

面向LOFAR应用的160Gbit/s OTDM试验平台

报告了一个用于低频射频天线网络LOFAR的160 Gbit/s 演示平台.文章介绍了LOFAR网络结构以及用于LOFAR长臂的OTDM/WDM系统结构,回顾并探讨了用于实现160 Gbit/s系统的关键技术,并介绍了实验室中实现该160 Gbit/s OTDM/WDM演示平台所采用的技术方案。出于经济性考虑,所有的关键系统功能都采用自己搭建方案.