Silica-based integrated optic Mach-Zehnder multi/demultiplexerfamily with channel spacing of 0.01-250 nm

A Mach-Zehnder (MZ) interferometer design is presented for application to wavelength-division multiplexed/frequency division multiplexed (WDM/FDM) systems. A variety of integrated-optic devices with low loss and low crosstalk, using silica-based waveguides, are demonstrated. MZ interferometers operate as multi/demultiplexers or frequency-selection switches. The channel spacing is determined by the waveguide arm length difference, and a spacing range of 1 GHz to 36 THz, corresponding to a wavelength spacing of 0.008-250 nm, is achieved. The devices for the WDM region have low fiber-to-fiber loss of 0.5 dB, and the devices for the FDM region have higher losses of 2-5 dB. Crosstalk of less than -15 dB was obtained for all the devices. A 5-GHz-spaced 16-channel frequency selection switch and a 10-GHz-spaced eight-channel multi/demultiplexer were also fabricated with a total loss of 5 dB and total crosstalk of -10 dB or less     

Analysis and Development of Fixed and Variable Waveband MUX/DEMUX Utilizing AWG Routing Functions

We develop and analyze a new waveband multi/demultiplexer that exploits the routing functions of arrayed-waveguide gratings (AWG). The device can accommodate multiple input/output fibers simultaneously and be implemented monolithically using silica planar lightwave circuit (PLC) technology. We analyze AWG port usage for variants of the proposed multi/demultiplexers. The important characteristic of the device, its coherent and incoherent crosstalk performance is investigated. A technique to reduce the crosstalk is presented. We extend the capability of the device so that the waveband bandwidth can be changed by adding small switches. Experiments confirm the excellent performance of the proposed waveband multi/demultiplexer.      

Low-loss phased-array based 4-channel wavelength demultiplexerintegrated with photodetectors

A 4-channel phased-array wavelength division demultiplexer with 1.8 nm channel spacing at 1.54 μm has been monolithically integrated with photodetectors in InP/InGaAsP. On chip losses are 3.5 to 4.5 dB. These are the lowest losses reported so far for demultiplexers monolithically integrated with photodetectors. Nearest neighbor crosstalk ranges from -12 to -21 dB     

Design and realization of polarization independent phased arraywavelength demultiplexers using different array orders for TE andTM

A method for designing polarization independent phased-array wavelength demultiplexers, using different array orders for TE and TM, is described and analyzed with respect to fabrication variations. Flattening of the wavelength response is shown to improve fabrication tolerances. A four channel phased-array wavelength demultiplexer with at least 0.2 nm of polarization independent flattened response for each channel (spacing 1 nm) has been made with an insertion loss of 1.5-3 dB and a crosstalk of -17 to -19 dB     

8通道-1.6nm Si纳米线阵列波导光栅的设计与制作

设计了基于绝缘层上硅(SOI)材料的8通道Si纳米线阵列波导光栅(AWG),器件的通道间隔为1.6nm,面积为420μm×130μm。利用传输函数法模拟了器件传输谱,结果表明,器件的通道间隔为1.6nm,通道间串扰为17dB。给出了结合电子束光刻(EBL)和感应耦合等离子(ICP)刻蚀技术制备器件的详细流程。光谱测试结果分析表明,器件通道间隔为1.3～1.6nm,通道串扰为3dB,中心通道损耗为11.6dB。     

Crosstalk reduction in arrayed-waveguide grating multiplexer/demultiplexer using cascade connection

This paper proposes a cascade-connected arrayed-waveguide grating (AWG) as a solution to the problem of crosstalk accumulation in a large-scale AWG multiplexer/demultiplexer (MUX/DEMUX) and demonstrates a 64-channel cascaded AWG module with a very low background crosstalk of less than -80 dB and a total crosstalk of about -34 dB. In this paper, the authors densely integrate 64 additional compactly designed crosstalk-suppressing AWGs whose bandwidths were carefully optimized and directly attach them to a conventional 64-channel AWG. Consequently, in addition to a very low crosstalk, a low insertion loss and a compact size without passband shape distortion are achieved with this module. Based on the performance of the cascaded AWG module, it is then estimated that it is possible to realize a 1000-channel AWG MUX/DEMUX that is free from the problem of crosstalk accumulation.     

基于3 μm-SOI的波分复用/解复用器与电吸收型VOA的单片集成

波分复用/解复用器与可调光衰减器的是光通信系统中的重要元器件。为了得到制备工艺简单、响应速度快的二者的单片集成芯片,并且考虑到其与其他不同光器件的集成可能性,在绝缘体上硅材料制作了16通道、信道间隔200 GHz的阵列波导光栅复用/解复用器与电吸收型可调光衰减器的单片集成。该器件的片上损耗小于7 dB,串扰小于-22 dB。电吸收型VOA在20 dB的衰减量下的功耗为572 mW （106 mA,5.4 V）。此外,该器件可以实现光功率的快速衰减,在0~5 V的外加方波电压下,VOA上升及下降时间分别为50.5 ns和48 ns。     

17×17 硅基聚合物信道箱形光谱阵列波导光栅的制备

Arrayed waveguide grating (AWG) is a key device in wavelength-division multiplexing (WDM) system, and the flat spectral response of the AWG device is required. In this paper, the RIE process has been improved. By using the steam- redissolution technique, the insertion loss and the crosstalk have been reduced. Experimental results show that the central wavelength is 1550.86nm, and 3-dB bandwidth is about 0.478 nm, insertion loss is 10.5 dB, crosstalk is about –22 dB. The insertion loss of an AWG device is reduced by about 3 dB for the central channel and 4.5 dB for the edge channels, and the crosstalk is reduced by 2.5 dB after the steam- redissolution.     

An array of photonic filtering advantages:arrayed-waveguide-grating multi/demultiplexers for photonicnetworks

The author introduces the principles, fabrication techniques, and recent progress of planar-type arrayed-waveguide-grating (AWG) multi/demultiplexers, which have been developed for wavelength division multiplexing (WDM)-based photonic networks. The AWG has already been used in point-to-point WDM systems and is a key component in the construction of flexible and large-capacity WDM networks. This is because, compared with conventional filters consisting of thin-film interference filters and micro-optics, the AWG offers the advantages of low loss, high port counts, and mass productivity. Further progress on the AWG is expected to contribute greatly to the construction of future photonic networks including optical add/drop multiplexing systems and optical crossconnect systems     

Fabrication of 17 × 17 polymer/Si arrayed waveguide grating with flat spectral response using steam-redissolution technique

Arrayed waveguide grating (AWG) is a key device in the wavelength-division multiplexing (WDM) system, and the flat spectral response of the AWG device is required. In this paper, the RIE process has been improved. By using the steam-redissolution technique, the insertion loss and the crosstalk have been reduced. Experimental results show that the central wavelength is 1550.86 nm, the channel spectral response flatness is about 1.5 dB, 3-dB bandwidth is about 0.478 nm, insertion loss is 10.5 dB, and crosstalk is about-22 dB. The insertion loss of an AWG device is reduced by about 3 dB for the central channel and 4.5 dB for the edge channels, and the crosstalk is reduced by 2.5 dB after the steam- redissolution.     

Fabrication of 17×17 polymer/Si arrayed waveguide grating with flat spectral response using steam-redissolution technique

Arrayed waveguide grating(AWG) is a key device in the wavelength-division multiplexing(WDM) system, and the flat spectral response of the AWG device is required.In this paper,the RIE process has been improved.By using the steam-redissolution technique,the insertion loss and the crosstalk have been reduced.Experimental results show that the central wavelength is 1550.86 nm,the channel spectral response flatness is about 1.5 dB,3-dB bandwidth is about 0.478 nm,insertion loss is 10.5 dB,and crosstalk is abo...     

An Analytic Approach to Random Phase Error and Its Impact on the Performance and Design of Arrayed-Waveguide Gratings

Random phase error due to fabrication process causes the filter response of arrayed-waveguide grating (AWG) to degrade, especially in terms of crosstalk. In the side-lobe region, which is critical to the channel crosstalk performance, each instantiation of the random phase error can yield a significantly different filter transmission than that of the average for that level of phase error. In this report, the statistical behavior of the AWG filter transmission in the side-lobe region is studied analytically. Both the distribution of random side-lobe level at a given wavelength and an upper bound of the outage probability for side-lobe maxima are given in a simple closed form. Accordingly, a crosstalk margin needs to be allocated to ensure a given fabrication yield and this is shown to depend on the fractional bandwidth of the AWG filter. For filter shapes that are close to Gaussian, this crosstalk margin can be 8 dB or more above the average crosstalk level, for small fractional bandwidth of about 1% and fabrication yields of 80% or higher. These relations should be useful to AWG designers particularly when the underlying fabrication process is susceptible to nonnegligible random phase errors.     

基于SOI的16通道200GHz阵列波导光栅

设计并制作了基于绝缘体上硅(SOI)材料的1×16阵列波导光栅(AWG).该AWG器件的中心波长为1 550 nm,信道间隔为200 GHz,采用了脊型波导结构.首先确定了波导的结构尺寸以保证单模传输,并利用束传播法(BPM)模拟了波导间隔、弯曲半径和锥形波导长度等参数对器件性能的影响,对器件结构进行了优化,同时也利用BPM方法模拟了器件的传输谱.模拟结果显示:器件的最小信道损耗为4.64 dB,串扰小于-30 dB.根据优化的器件结构,通过光刻等半导体工艺制作了AWG,经测试得到AWG器件的损耗为4.52～8.1 dB,串扰为17～20 dB,能够实现良好的波分复用/解复用功能.     

The role of photomask resolution on the performance ofarrayed-waveguide grating devices

The crosstalk performance of an arrayed-waveguide grating (AWG) multiplexer or demultiplexer is primarily caused by random optical phase errors introduced in the arrayed waveguides. Because the layout of waveguides on a wafer is patterned via photomask through the photolithography process, the resolution of a photomask has a direct influence on the phase errors of an AWG. The paper presents a theoretical analysis on the phase error caused by photomask resolution and other basic design parameters. Both calculation and measurement results show that a high-resolution photomask (better than 25 nm) is a critical requirement to produce low-crosstalk (less than -30 dB) AWG demultiplexers. We also investigate the effect of nonideal power distribution in the arrayed waveguides because it contributes considerable phase errors when material impurity is not well controlled during wafer fabrication. Basic criteria of power profile truncation, number of grating waveguides, and material index variation are also summarized     

Low-loss wavelength division multiplexing (WDM) devices for single-mode systems

We report here on single-mode microoptic wavelength division multiplexing (WDM) devices with two channels located at 1275 and 1345 nm, respectively. Data are presented for four multiplexers and four demultiplexers. The average insertion loss for the multiplexers was 0.5 ± 0.2 and 1.0 ± 0.3 dB for the short and long wavelength channels, respectively. For the demultiplexers, the average losses were 0.8 ± 0.2 dB and 1.0 ± 0.1 dB, respectively. The full channel widths of the demultiplexers for 0.5 dB of additional loss were about 22 nm. All measurements included the presence of prototype precision single-mode connectors. The multiplexers were based on interference filters and GRIN lenses with identical single-mode fibers used for inputs and output. The demultiplexers employed diffraction gratings and GRIN lenses with 50- μm core graded-index output fibers. In addition three of the demultiplexers included a third output channel centered at 1521 nm. The 28- dB dynamic range of the monochromator-based test appartus was insufficient to evaluate the crosstalk performance. Measurements on two demultiplexers, using a 1295-nm laser, yielded values of -33 and -38 dB, respectively for the crosstalk in the 1345-nm channel.     

硅基竖直耦合三环谐振波分复用器的特性

对1×N信道硅基竖直耦合三环谐振波分复用器的传输特性进行了分析,给出了光学传递函数的公式.在中心波长1550.918nm、波长间隔1.6nm的情况下,对其振幅耦合比率、波谱响应、分光光谱、插入损耗、信道间的串扰进行了数值模拟.计算结果表明,该器件具有以下良好性能:若取小环与信道间的振幅耦合比率为0.27,小环与大环间的振幅耦合比率为0.06,该器件具有箱形波谱响应,输出光谱中的次峰值已被抑制到-25dB,谐振峰平坦且陡峭,3dB带宽约为0.28nm,每条输出信道的插入损耗及串扰较小,插入损耗小于0.71dB,串扰可降至-53dB以下.     

Athermal silica-based arrayed-waveguide grating (AWG)multi/demultiplexers with new low loss groove design

A new low loss groove design for athermal silica-based AWG multi/demultiplexers is proposed. The insertion loss was <3.2 dB with an excess loss of 0.4 dB. The temperature dependence of the channel wavelength change was suppressed to be below 2.5 GHz in the 0-85°C range     

Design and fabrication of 25-channel 200 GHz AWG based on Si nanowire waveguides

A 25-channel 200 GHz arrayed waveguide grating (AWG) based on Si nanowire waveguides is designed, simulated and fabricated. Transfer function method is used in the simulation and error analysis of AWG with width fluctuations. The 25-channel 200 GHz AWG exhibits central channel insertion loss of 6.7 dB, crosstalk of ?13 dB, and central wavelength of 1 560.55 nm. The error analysis can explain the experimental results of 25-channel 200 GHz AWG well. By using deep ultraviolet lithography (DUV) and inductively coupled plasma etching (ICP) technologies, the devices are fabricated on silicon-on-insulator (SOI) substrate. This work has been supported by the National Key Research and Development Program of China (No.2016YFB0402504), and the National Natural Science Foundation of China (Nos.61435013 and 61405188). E-mail:zhangjiashun@semi.ac.cn      

A 45-channel 100 GHz AWG based on Si nanowire waveguides

A 45-channel 100 GHz arrayed waveguide grating (AWG) based on Si nanowire waveguides is designed, simulated and fabricated. Transfer function method is used in the spectrum simulation. The simulated results show that the central wavelength and channel spacing are 1 562.1 nm and 0.8 nm, respectively, which are in accord with the designed values, and the crosstalk is about ?23 dB. The device is fabricated on silicon-on-insulator (SOI) substrate by deep ultraviolet lithography (DUV) and inductively coupled plasma (ICP) etching technologies. The 45-channel 100 GHz AWG exhibits insertion loss of 6.5 dB and crosstalk of ?8 dB. This work has been supported by the National High Technology Research and Development Program of China (No.2015AA016902), and the National Natural Science Foundation of China (Nos.61435013 and 61405188). E-mail:zhangjiashun@semi.ac.cn      

Expansion of channel number in optical demultiplexer using cascaded photopolymer volume gratings

A method to expand the number of channels in the optical demultiplexer (DMUX) using two cascaded photopolymer volume gratings is proposed and presented. A 0.4-nm-spaced 130-channel DMUX with the channel uniformity of 3.5 dB, the 3-dB bandwidth of 0.12 nm, and the channel crosstalk of -20 dB is experimentally demonstrated.