Translation of Gbps Phase-Modulated Optical Signal From Near-Infrared to Visible Band

Phase-coded optical signal was spectrally translated from the conventional near-infrared communication band to the visible band. Spectrally narrow 780-nm pump was combined with phase-modulated 1575-nm signal in a small core photonic crystal fiber (PCF), to generate 518-nm idler through parametric process. The phase-modulated idler carrying 1-Gbps information was received in an error-free manner. The onset of the stimulated Brillouin scattering (SBS) was found to be a major limitation for conversion efficiency and noise performance. The SBS effect and the birefringence properties of the small core PCF were studied at both 780 and 1550 nm and their impact on the parametric process was analyzed.     

Continuous-Wave Band Translation Between the Near-Infrared and Visible Spectral Ranges

Wavelength conversion based on degenerate four-wave mixing in a photonic crystal fiber with two zero-dispersion wavelengths is investigated both theoretically and experimentally. The proposed concept of universal band translation in a single-pass traveling-wave structure offers a wavelength band rather than a single-wavelength mapping between distant spectral ranges. Near-infrared signals are modulated using both harmonic and pseudorandom bit sequences and translated to the visible optical band. Multiple-channel translation, which produces wavelength-division-multiplexed idlers in the visible band, is demonstrated for the first time. The performance of the translation process is measured both spectrally and temporally for both single- and multiple-channel signals     

基于多孔光纤的参量波长变换

通过改变多孔光纤中的芯区面积、空气孔的直径和分布．可以灵活地设计其导波特性。利用耦合波方程分析了参量波长变换的基本原理．讨论了信号波长固定情况下相位失配和抽运波长之间的关系。对基于多孔光纤的参量波长变换的转换效率进行了数值模拟．并和实验测量的数据进行了比较．结果表明它们的结果相一致。采用15m长的多孔光纤可以获得约10nm的3dB调谐带宽．最大转换效率约为-16dB．并且采用较低色散斜率值的多孔光纤可以进一步增大调谐范围。因此．利用多孔光纤可以实现紧凑的波长变换器。     

BBO晶体Ⅰ类相位匹配从可见光到近红外光宽带参量放大的带宽研究

超快激光的应用,需要有高功率、窄脉宽和宽调谐的激光光源。飞秒光参量放大是产生可调谐、短至几个飞秒光脉冲的一种重要方法。为获得极窄的飞秒光脉冲,飞秒光参量放大器就应该有尽可能大的本征带宽。理论研究了BBO晶体在Ⅰ类非共线相位匹配条件下的宽带参量放大特性。将多色相位匹配技术应用于飞秒光参量放大,推导出信号光带角色散时的宽带运转条件。分别介绍了从可见光到近红外光选取合适的参数实现宽带运转的方法。基于400nm蓝光抽运的BBO晶体光参量放大器(OPA),系统地分析了非共线角和信号光角色散值对相位失配和参量带宽的影响。研究结果表明选取适当非共线角和在近红外光中引入适当的角色散可极大提高参量带宽。     

Wavelength Conversion Technologies

This paper reports a review of the different technologies used for wavelength conversion in wavelength-division multiplexed networks. The strengths and the weaknesses of the competing technologies, including optoelectronic wavelength conversion, four-wave mixing, difference frequency generation, cross-gain and cross-phase modulation in semiconductor optical amplifiers, are stressed with regard to conversion speed, transparency and regeneration of the converted signal.     

Wide-Band and -Range Tunable Dispersion Compensation Through Parametric Wavelength Conversion and Dispersive Optical Fibers

An intrinsically ultrafast, wide-band, and -range tunable dispersion compensation (TDC) is realized through parametric wavelength conversion in conjunction with fibers with large dispersion slope such as dispersion compensating fibers. The proposed schemes have unique potentials that they can operate with fast response in a truly colorless manner and are capable of producing two orders of magnitude larger bandwidth-dispersion product than conventional ones. After the discussions on the operating principle and design issues, a proof-of-concept experiment is performed to verify the static operations achieving a tunable dispersion range larger than plusmn280.5 ps² for 2.47 ps optical pulses.     

Ultrawideband Wavelength Conversion Using Cascaded SOA-Based Wavelength Converters

An all-optical wavelength converter with a large wavelength hopping range is proposed and demonstrated. This converter consists of multistage cascaded wavelength converters using semiconductor optical amplifiers each with different gain band. Each of the cascaded wavelength converters enables us to perform both noninverted (NIV) and inverted (IV) operations. Conversion performance is compared at NIV and IV operations in terms of static characteristics as a function of input/output power of the converter. While good conversion performances are achieved at both operations, the IV wavelength conversion has better cascadability to obtain a high-quality converted signal for the cascaded scheme. Moreover, signal amplitude regeneration is demonstrated by repeating the IV wavelength conversion. Finally, we successfully demonstrate, for the first time, ultrawideband wavelength conversion, including over 300-nm wavelength hopping to the shorter wavelength side with a triple-stage cascaded wavelength converter     

Reducing Wavelength Conversion Range in Space/Wavelength Switches

Wavelength converters with a wide conversion range are usually technologically infeasible. The limit of conversion range introduces new constraints in the construction of space/wavelength switches. In this letter, we show how we can reduce the wavelength conversion range without compromising the nonblocking properties. We use the space/wavelength switches that are based on the wavelength band converters to illustrate our technique.      

可见光波段激光功率测试系统

利用高精度数据处理技术与二阶巴特沃兹低通滤波技术研制了一套可与液晶显示器(LCD)或计算机连接工作的激光测试系统,用于可见光波段巾小功率激光器的光功率、光功率稳定性等参数的检测,最小分辨率为0.01 mW.实验验证,系统的测量误差小于±5%.该激光测试系统工艺简单,价格低廉,检测结果直观、明确,测试精确度高,可广泛应用于中小功率激光器的生产、检测和使用.     

基于波长组合的多元线性回归在近红外光谱波长优选中的应用

在自主研发的滤光片型近红外检测仪上通过用多元线性回归算法选择最优定量波长,为仪器提供了稳健的定量模型.在制备的26个蛋白质含量为10%～16%的样品的基础上,用DPS软件建立模型,选取各个波长组合进行多元线性回归,然后用多元线性回归给出的与最大检验相关系数定量模型对应的波长组合作为最优波长.试验结果表明,其最优波长分别对应于1、3、4、8号滤光片,校正相关系数和检验相关系数分别为0.847和0.707.用这种方法得到的最优定量模型的实际预测能力相对较强,优选出的波长是可靠的.     

Multichannel Photonic Crystal Wavelength Filter Array for Near-Infrared Wavelengths

Multichannel wavelength filters consisting of 2-D photonic crystal (PhC) for the near-infrared wavelength region (~800 nm) are demonstrated. The filter is a thin-film wavy multilayer structure and is fabricated by the autocloning method, which is based on a radio frequency bias sputtering process. Twelve long-pass-type filter regions are integrated on a common silica substrate. Sharp cutoff characteristics and almost equal channel spacing are experimentally verified. To precisely control the effective lattice constant of PhC, a modulated lattice structure on the substrate is utilized     

波长可调谐准相位匹配光学参量振荡器

利用掺氧化镁周期性极化铌酸锂晶体,对信号光单谐振的准相位匹配光学参量振荡器 的温度调谐特性和输出功率特性进行了理论与实验研究。以LD泵浦的声光调Q准连续Nd∶YAG激光器作为泵浦源,获得了1561～1672nm的可调谐输出,信号光在1064nm泵浦光平均功率为1. 728W时,最大信号光输出为297mW。     

交叉增益型波长转换器的参数优化

在考虑放大自发辐射消耗载流子的前提下 ,运用放大器的分段模型和传输矩阵方法 ,理论分析了交叉增益(XGM)型波长转换器应用于通信系统中的误码率特性。基于误码率特性的分析 ,对波长转换器中放大器有源腔长度和内部损耗、转换波长间隔、探测功率和平均抽运功率等参数进行了优化。     

Plasmonic States From Visible Light to Microwaves

Plasmonics is a phenomenon often considered in the visible light and near infrared, whereas typical metal waveguide modes are studied in the microwave regime. We demonstrate how plasmonic modes become conventional waveguide modes as the frequency varies from visible light to microwaves. In particular, given the metal permittivity at microwaves, the plasmonic dispersion becomes the conventional waveguide dispersion. Moreover, the surface plasmon dispersion at a single metal/insulator boundary can be extracted over a metal/insulator/metal (MIM) heterostructure if the metal-to-metal spacing is taken infinite. In doing so, the coupling effect of plasmonic modes is clearly revealed. As the symmetric coupled plasmon mode is known to correspond to the TEM $({hbox{TM}}_{0})$ mode, we found that the antisymmetric coupled surface plasmon mode is essentially related to the ${hbox{TM}}_{1}$ mode.      

全光波长变换技术的研究进展

全光波长变换技术是高速光纤通信网络的关键技术之一,是高速光纤通信系统中急需解决的问题.文章结合作者所研究的内容,对近年波长变化技术的研究情况进行了全面的回顾和总结,对几种全光波长变换技术的机制、特点和实现进行了比较分析.     

A Visible and Near-Infrared Light-Fueled Omnidirectional Twist-Bend Crawling Robot

In recent years, although light-driven soft actuators have attracted intense scientific attention and achieved remarkable progress, the design and construction of an intelligent robotic system with maneuverability, self-adaptability, untethered control, and greater freedom of action, in particular the omnidirectional motion capability on a plane, remains challenging. Herein, four types of photo-thermal fillers and an unprecedented twist-bend actuation mode is introduced into a liquid crystal elastomer-based soft robot. The obtained twist-bend crawling robot not only exhibits in situ rotation, four-way turning, and four-way linear motion under light irradiation with four wavelength bands (520, 655, 808, and 980 nm), but also demonstrates the ability to avoid obstacles in complex geographical environments. This work may bring a new perspective for fabrication and development of soft robots that can adapt to dynamic and complex environmental conditions.     

全光波长变换器研究进展

分析了全光波长变换器的几种方案，阐述了各自的优缺点，指出利用级联二阶非线性光学晶体的波长变换方案是目前的发展趋势。     

基于四波混频的波长变换技术

基于四波混频的波长变换技术由于其严格的透明性被认为是很有发展前途的波长变换技术。通过非线性极化方程推导了四波混频的相位匹配条件和耦合方程 ,进而介绍了基于四波混频的波长变换的原理和应用方案。     

全光波长转换技术研究

全光波长转换器(AOWC)是目前全光网研究中的一个热点问题。本文先简要介绍AOWC所采用的基本原理 ,然后根据转换器所用的非线性器件 ,分类介绍了目前常见全光波长转换器实现方案 ,并对当前的研究动态提出了看法