微环谐振器中各参数对光速控制输出脉冲畸变的影响仿真分析

利用微环谐振器进行光速控制时,各参数对光脉冲传输的影响是不可忽略的,它除了导致光脉冲展宽,还引起脉冲的畸变。基于微环谐振器的传输特性,推导了单环谐振器的二阶色散和三阶色散表达式,针对无损耗/增益情形,分析了利用微环谐振器进行光速控制时,高阶色散和输入脉冲中心波长对输出脉冲畸变的影响,分析了损耗/增益对单环谐振器输出脉冲畸变的影响。结果表明,二阶色散导致脉冲展宽,三阶色散导致脉冲畸变,输入脉冲中心波长位置影响脉冲分裂谷底的深浅,而损耗和增益影响脉冲畸变情况。为利用微环谐振器实现光速控制的应用提供了设计优化依据。     

基于微环谐振器的超紧凑微波光子滤波器的设计

设计了一个基于硅基微环的超紧凑的微波光子滤波器,用以提高硅基微波光子器件的集成密度及增大其自由光谱范围。根据波导光学的耦合模理论,推导出双环并联谐振器的光强传递函数,并通过仿真得到了微波光子滤波器的输出特性。结果表明:当微环半径为0.79 m时,谐振器中直波导宽度为0.3 m,环形波导宽度为0.25 m,滤波器的自由光谱范围为140 nm,插入损耗为0.5 dB,半峰全宽为7 nm,此滤波器的性能完全满足粗波分复用系统的要求。     

High‐capacity soliton transmission for indoor and outdoor communications using integrated ring resonators

A system consisting of a series of microring resonators, incorporating an add/drop system, is presented in order to create ultra‐short spatial and temporal single and multisoliton pulses, which can be used for indoor and outdoor optical communications. Chaotic noise can be generated by a bright soliton pulse propagating inside a nonlinear microring resonator system. The results obtained show that a single temporal and spatial soliton pulse, with full width at half maximums of 75 fs, 80 fs, 700 fs, 4.4 ps, and 0.30 nm, can be generated. The add/drop system can be used to generate a high number of ultra‐short soliton pulses in the ranges of nanometer/second and picometer/second. The simulated multisolitons have full width at half maximums of 16 ps, 20 pm, 130 ps, and 35 pm and free spectrum ranges of 500 ps, 0.57 nm, 3.5 ns, and 1.4 nm, respectively. The multisolitons generated at the drop port can be used in indoor optical communications, where the ultra‐short pulses with a variety of central wavelengths (from λ = 1550 to λ = 1560) from the through port can be multiplexed‐demultiplexed along an optical fiber with a length of 50 km. The filtered signals can be obtained at the end of the transmission link used for optical outdoor communications. Copyright © 2013 John Wiley & Sons, Ltd.     

Polymer microring coupled-resonator optical waveguides

We present measurements of the transmission and dispersion properties of coupled-resonator optical waveguides (CROWs) consisting of weakly coupled polymer microring resonators. The fabrication and the measurement methods of the CROWs are discussed as well. The experimental results agree well with the theoretical loss, waveguide dispersion, group delay, group velocity, and group-velocity dispersion (GVD). The intrinsic quality factors of the microrings were about 1.5/spl times/10/sup 4/ to 1.8/spl times/10/sup 4/, and group delays greater than 100 ps were measured with a GVD between -70 and 100 ps/(nm/spl middot/resonator). With clear and simple spectral responses and without a need for the tuning of the resonators, the polymer microring CROWs demonstrate the practicability of using a large number of microresonators to control the propagation of optical waves.     

波导微环共振滤波器的滤波特性分析

根据波导耦合模理论详细研究了微环共振滤波器的滤波特性,分析了单环、串联双环、串联三环结构等波导微环共振滤波器的滤波特点。通过模拟计算发现,滤波带宽平坦化程度和信道串扰大小主要依赖于由波导构成的各方向耦合器之间的功率耦合比k,同时微环波导的损耗是器件滤波特性劣化的重要原因。在一定优化参数条件下,多环结构的滤波效果优于传统单环结构,并且各方向耦合器功率耦合比k值的优化取值范围扩大,降低了器件工艺实现难度。     

All-optical switching in a laterally coupled microring resonator by carrier injection

We demonstrate all-optical switching in a laterally coupled GaAs-AlGaAs microring resonator by carriers injections. The ring waveguide is optically pumped just above its bandgap energy, which results in a temporal tuning of the microring resonant wavelengths by the refractive index change due to the induced carriers. A switching window of 20 ps could be obtained and is only limited by the carrier recombination time. A switching energy of a few tens of picojoules per pulse is used and has resulted in a 1.2-nm wavelength shift of the microring resonance.     

Waveform Standards for Electrooptics: A Pulse Duration Comparison (Short Paper)

A transfer standard has been developed for use in comparing the measurement capability of the Automatic Pulse Measurement System (APMS) at the National Bureau of Standards to that of the recently developed electrooptic samplers. This transfer standard is a comb generator driven by a 90-MHz sine wave. Using this standard, measurements were made of the pulse waveform of a comb generator output with both the APMS and an electrooptic sampler. A comparison was then made of the pulse duration (full width at half maximum) obtained in the two waveform measurements. The result was a duration of 102 ps as measured by the APMS and 112 ps as measured by the electrooptic sampler. The signal-to-noise ratio at the comb generator input was improved over that of previous measurements, and a correction for pulse broadening was made to achieve this result. The pulse broadening was caused by the impedance mismatch between the sampler and the transmission system (50 Omega).     

Temperature insensitive vertically coupled microring resonatoradd/drop filters by means of a polymer overlay

The temperature dependence of vertically coupled glass microring resonator add/drop filters is investigated. Measurements show that the passband of the air-clad microring resonator filter increases with temperature at a rate of 0.0137 mm/°C. Using a PMMA-TFMA polymer that has an opposite refractive index temperature gradient than glass as the overlay of the microring resonator, the temperature dependence of the filter is compensated to -0.0025 nm/°C in the operation range of 25°C to 55°C     

Pulse broadening in long-span dispersion-free single-mode fibres at 1.5 ?m

Dispersion-free single-mode fibres at 1.5 ?m were fabricated by controlling their waveguide dispersion and dopant-dependent material dispersion. Pulse broadening in the 20 km long fibre was measured by using a laser diode operated at 1.5 ?m. Measured pulse broadening was 1.3 ps/km nm, which is in good agreement with theoretical results. The present experiment confirms that it is beneficial to use such fibres for large-capacity and long-distance transmission media.     

串联微环谐振器的光学特性

根据波导耦合方程,导出了串联微环谐振器的传输矩阵,并分析了环数、环间耦合系数以及损耗对串联微环谐振器输出特性的影响。数值模拟表明,串联微环谐振器具有光子带隙的特征。当环数增加时,通带内满足谐振条件的波长数增加;当环间耦合系数增加时,可使通带带宽加宽;通过适当选择环数和环间耦合系数,可以实现滤波和波分复用(WDM)的功能。选用脉冲宽度为50 ps的高斯型激光脉冲注入微环谐振器,发现当环间耦合系数较小时,出射脉冲相对于入射脉冲具有光学延迟的效果,并且随着环数的增加,延迟时间逐渐增大,而当环间耦合系数较大时,光学延迟效果不明显。     

基于氮化硅微环和载波分离的可重构微波光子带通滤波器

基于Add-Drop型氮化硅微环滤波器,利用光学单边带调制和光载波分离的方法,实现可重构微波光子带通滤波器。滤波器带宽和带外抑制比分别达到726 MHz和37.0dB。并且通过改变光载波波长实现1.64~23.41GHz的滤波器频率调谐;通过调节微环耦合系数实现0.683~2.246GHz的滤波器带宽调谐,在带宽调谐范围内带外抑制比大于26dB。     

硅基槽型微环谐振器及其调谐特性研究

仿真和实验研究了含槽型(slot)光波导的反馈波导型微环谐振器的特性,将槽型光波导集成到Si基微环谐振器中,丰富Si基光波导的功能,为新型光电子器件的实现提供途径。通过锥形波导结构实现从传统波导到槽型波导的模式转换,减小传输损耗,采用时域有限差分法(FDTD)研究了光功率的分布和模式转换过程。结果显示,光功率逐渐转移到锥形结构两侧的槽型波导中并最终形成槽型波导中的传输模式,通过优化锥形结构能实现较高的模式转换效率,可以达到90%以上。采用电子束刻写技术和等离子刻蚀技术制备了反馈波导型槽型微环谐振器。实验显示,锥形波导能够实现模式的转换,光传输过程良好。通过在槽型波导中填充电光聚合物来改变槽型光波导的折射率,测量结果显示,传输谱谐振峰发生了明显移动,移动幅度达到5.6nm,器件具备很好的可调谐性。     

Ultrasmall Thermally Tunable Microring Resonator With a Submicrometer Heater on Si Nanowires

An ultracompact widely tunable thermooptical (TO) microring resonator (MRR) filter based on Si nanowires is presented. The Si nanowire waveguide has a insulator, Si core, a up-cladding, and a thin metal film at the top. The metal circuit along the microring is used as a submicrometer heater which has the same width as the Si nanowire waveguide. The up-cladding is optimized to reduce the light absorption of the metal as well as to have a good heat-conduction from the heater to the Si core. Two pads used as the contact points for the probes connecting to the electrical power are perpendicularly connected to the microring by using optimized T-junctions (with a low excess loss of about 0.06 dB per T-junction). With such a design, the present thermally tunable microring resonator (MRR) can be fabricated by using a standard fabrication process with a single lithography process, which is much simpler than the fabrication with double lithography processes used for the conventional TO components. Finally, the simulation results show that the designed MRR has a wide tuning range of about 20 nm with a low heating power of 5 mW.     

Optical Differential-Phase-Shift-Keying Demodulation Using a Silicon Microring Resonator

We have for the first time experimentally demonstrated an ultrasmall, low power penalty, and robust 10-Gb/s differential-phase-shift-keying demodulator using a silicon-based microring resonator. The microring resonator is compatible with a wide range of signal bit rates. In optical transmission measurements with 11.6-km nonzero dispersion-shifted fiber, the microring resonator demodulator had comparative power penalty compared with a Mach–Zehnder delay interferometer both in single ended detection. Error-free detection was achieved.      

160 Gbit/s OTDM signal transmission over 26 km photonic crystal fibre

A 160 Gbit/s (=10 Gbit/s X 16) optical time-division multiplexing (OTDM) signal is successfully transmitted over a 26 km-long photonic crystal fibre (PCF). The transmission induced signal pulse broadening is suppressed to only 0.2 ps (from 2.1 to 2.3 ps) because the fabricated PCF has low polarisation-mode dispersion (PMD) of 0.1 ps/km^1/2, and the total chromatic dispersion of the transmission line is suppressed to 0.015 ps/nm by using a dispersion-compensation fibre. The transmitted signal is demultiplexed using four-wave mixing in a 100 mlong dispersion shifted fibre, where a phase modulation-based 10 GHz pump pulse source is newly adopted.     

太赫兹硅基微环谐振器的设计与分析

设计了一个工作频率在太赫兹大气传输第一窗口的硅基波导型微环谐振器。利用传输矩阵法和耦合模理论计算微环谐振器的传输函数,并对波导耦合系数进行分析,获得微环谐振器的临界耦合条件。采用时域有限差分法分析微环谐振器的性能参数,并与串联双环谐振器性能参数相比较。结果表明：单环谐振器的自由谱宽范围为27 GHz,插入损耗为0.3 dB。单环与双环谐振器的响应谱线形状因子分别为0.16和0.52,即串联双环谐振器使谐振谱线顶端更平坦,滚降度增高。Abstract：关键词：     

Improved on-chip self-triggered single-event transient measurement circuit design and applications

Single-event transient (SET) induced soft errors are becoming more and more a threat to the reliability of electronic systems in space. The SET pulse width is an important parameter characterizing the possibility of an SET being latched by a sequential element such as a flip-flop. This paper improves the widely used on-chip self-triggered SET measurement circuit by changing it from a single SET measurement module to a combination of two modules. One module is responsible for measuring narrow SET pulse widths while the other is responsible for measuring modest and wide SET pulse widths. In this way, the range of measurable SET pulse width is increased. Pulsed laser facility is used to simulate single-event transients induced by single-particles. Experimental results demonstrate that the minimum accurately measured SET pulse width is decreased from 166.5 ps to 33.3 ps after adopting the proposed design when compared with the original one. SET pulse width broadening effect was also observed using the measurement system. The broadening factor was measured to be 0.123–0.143 ps/inverter.     

工艺公差对聚合物竖直耦合型微环谐振器性能的影响

本文根据波导耦合模理论,分析了工艺公差对聚合物竖直耦合型微环谐振器性能的影响。分析结果表明,工艺公差将引起谐振器传输光谱的漂移和光谱形状的改变。为了实现谐振器正常的滤波功能,我们对微环谐振器工艺公差的累积和补偿效应进行了讨论。     

Dispersion tolerance and transmission distance of a 40-Gb/sdispersion management soliton transmission system

We investigate the tolerance of the variation of average dispersion in a 40-Gb/s dispersion-managed soliton (DMS) transmission system. It is theoretically shown that dispersion tolerance is governed by pulse broadening and soliton interaction, and that the largest dispersion tolerance can be achieved by optimizing the pulse energy depending on the transmission distance. We construct a 40-Gb/s recirculating loop transmission system and show that the dispersion tolerance of over 180 ps/nm, which is much larger than that of a linear nonreturn-to-zero (NRZ) format system, can be realized by the optimization of the pulse energy at a transmission distance of more than 1000 km     

Free-standing all-polymer microring resonator optical filter

Free-standing all-polymer microring resonator optical filters as prototypical elements in flexible integrated lightwave circuits are demonstrated. The fabrication and measurement methods are discussed. The measured spectrum shows good agreement with theoretical expectations. The crucial 'critical' coupling condition is achieved, resulting in a measurement limited -27 dB extinction of the filter output on resonances