CN1694385B - 直接调制激光光学传输系统 - Google Patents
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Abstract
本发明揭示一种用于产生一调制光学信号供在色散光纤链路上发送的光学发射机,其中一宽带模拟射频信号输入被施加至一调制电路来直接调制一具有所述模拟信号输入的半导体激光器。所述发射机可进一步包括一接近所述激光器的温度感测器及一耦合至所述温度感测器用于响应所述激光器的一输出特征(例如,线性)调整所述激光器温度的负反馈控制回路。
Description
技术领域
本发明涉及一种用于模拟信号的光学传输系统,且特定而言涉及一种直接调制式固态激光器。更特定而言,本发明涉及使用一电子电路从一诸如半导体激光器等调幅传输装置中提供一线性输出,该调幅传输装置具有一因固有的非线性而自其输入畸变的输出。通过给该非线性装置的输入施加一预畸变信号来补偿该非线性装置的畸变。所选择的预畸变须使该非线性装置的畸变恢复该非畸变信号,从而能够在1550纳米的长色散光纤介质上发送信号。
背景技术
据认为,使用一电信号直接调制一发光二极管(LED)或半导体激光器的模拟强度是此项技术中熟知用于在光纤上传输诸如音频和视频等模拟信号的最简单方法之一。虽然此类模拟技术具有其带宽要求明显小于数字脉冲编码调制或模拟或脉冲频率调制的优点,但调幅可受到噪音和光源非线性的影响。
出于此原因,直接调制技术一直与1310纳米激光器结合使用,而该类1310纳米激光器仅应用于使用零色散光纤链路的短传输链路。对于城域(metro)及长距离光纤传输链路中的应用而言,链路的低损耗要求使用外部调制式1 550纳米激光器,但此类外部调制技术即复杂又昂贵。因此,本发明拟解决的问题是提供一种用于直接调制一1550纳米激光器的简单且低成本系统,以便可在城域(metro)和长距离光学网络中使用模拟光学输出。
已知,1550纳米激光器的直接调制用于数字光学传输系统中,例如密集波分多路复用系统等。
在先前技术中,尚不知存在可供1550纳米模拟光学传输系统使用的合适的低啁啾激光器。一种低啁啾激光器是数字光学传输系统中使用的外部共振腔激 光器,该种激光器在市场上可以买到。
一1550纳米模拟光学传输系统除需要低啁啾特性外,还必须具有高线性。某些模拟发射机中固有的畸变会阻碍一线性电调制信号以线性方式转变成一光学信号,并且会导致该信号发生畸变。该些效应对于需要卓越的线性来防止通道相互干扰的多通道视频传输尤其不利。高度线性化的模拟光学系统在商业电视传输、CATV、交互式电视及视频电话传输中具有广泛应用。
人们已对光学及其它非线性发射机的线性化进行了一段时间的研究,但提出的解决方案均存在实际缺陷。大多数应用所具有的带宽对于实际用途而言均太大。前馈技术需要复杂的系统组件,例如光功率组合器及多个光源。准光学前馈技术也存在类似的复杂性问题并且进一步需要相互区配极为精确的部件。
过去一直沿用的一种用于减少激光器或其它非线性装置中固有畸变的方法是实施预畸变。在此技术中,将一调制信号与一在振幅上与该非性装置内的固有畸变相等但符号相反的信号组合。当该非线性装置调制该组合信号时,该组合信号的预畸变会消除该装置的固有畸变并仅传输该源信号的线性部分。该预畸变信号通常为输入基频的加/减组合形式,其原因在于该些互调产物构成模拟信号传输中最肥沃的畸变源。举例而言,在有线电视的AM信号分配中,一特定频带上通常具有多达40个频率,因此,该些频率极有可能产生二阶和三阶互调产物。
该些预畸变技术一直用于现有的1310纳米光学发射机中,第6,288,814号美国专利已对此予以举例说明,该专利以引用方式并入本文中。
某些早期的预畸变技术通常是将一输入信号分成两个或更多个电路径并在一个或多个与该非线性传输装置中固有畸变相似的路径上产生预畸变。所产生的预畸变是该非线性装置固有畸变的反转,并且当与该输入再组合时可用于消除该装置固有畸变的影响。
在对该些信号进行再组合并发送至该非线性装置进行调制之前,可使用衰减将预畸变振幅匹配于装置固有畸变特性的振幅。然而,由于非线性装置的振 幅和相位畸变特性通常依赖于调制信号的频率,因此该方法具有粗糙性缺陷。较新的技术可提供对该些依赖于频率的非线性进行补偿的手段。
如果忽略纠正畸变的频率依赖性,所导致的结果对于诸多系统及带宽相对窄的信号而言尚可容忍,但当将一电TV信号转变为一用于电缆传输的光学信号时,则变得尤其麻烦。此等用于有线电视的信号可具有40或更多个输入频率,所有该些频率均需具有高品质的调幅信号。用于该信号的传输装置必须具有一格外高的线性度。
先进的多路径畸变电路较为灵活,且可极有效地对多种非线性装置的输出实施线性化。颁予Blauvelt等人的第4,992,754号美国专利即披露了一种此类多路径预畸变电路。该电路能够产生频率专有的畸变产物用来补偿依赖于频率的非线性,并用于需要一格外高线性度的应用,例如有线电视应用。
虽然多路径预畸变电路可广泛用于诸多应用中,但该等电路的设计却相当复杂。此复杂性在电路中的表现是该等电路对于仅需要中度线性化的应用而言过于昂贵。熟悉此项技术者会赏识一种供有限应用使用的设计相对简单的低成本电路,且假如此一电路可使用现信号传输应用中常用的低成本组件制作而成则更佳。
本文所述的电路可产生依赖于频率的三阶畸变。简单的三阶畸变(例如一理想型二极管所产生的三阶畸变)具有该畸变真实且不依赖于频率的性质。然而,许多非线性发射机或放大器包含诸如电感、电容或延迟等无功元件,该些元件可导致装置产生依赖于输入和输出频率及畸变频率的畸变。颁予Nazarathy的第5,161,44号美国专利揭示了一种该专利图5中所示的电路,该电路可产生基本真实的不依赖于频率的预畸变。出于偏压目的并为了阻断DC和AC电流,Nazarathy所揭示的电路中添加了电容器和电感器。然而,对于每一输入频率集合而言,Nazarathy所揭示的电路可能不具有与非线性装置所产生畸变在振幅上实质相同且在符号上相反的正确相位或频率依赖性。
因此,本发明即旨在解决该些及其它在操作1550纳米激光模拟光学传输系 统中所发现的因难。
发明内容
本发明的一个目的是提供一种使用一直接调制激光器的改良型光学传输系统。
本发明的另一目的是提供一种在1550纳米模拟光学传输系统中使用的低啁啾激光器。
本发明的再一目的是提供一种在1550纳米模拟光学传输系统中使用的预畸变电路。
本发明的再一目的是提供一种适合于长距离色散光纤介质的低啁啾高线性模拟光学传输系统。
本发明的再一目的是提供一种适合在长距离色散光纤介质的模拟光学传输系统中用于控制一低啁啾激光器的反馈电路。
本发明还有一目的是提供一种在一宽带模拟光学传输系统中使用的直接调制和畸变补偿方法。
本发明的特点
简要并概括而言,本发明提供:一种供在包括一模拟信号输入的色散光纤链路上使用的光学传输系统;一种低啁啾激光器;一种用于直接调制该激光器的调制电路;及一种用于减少半导体激光器中依赖于频率的畸变分量的预畸变电路。
本发明进一步提供一种低成本直接调制技术,该技术较佳包括一预畸变电路,以减小一诸如激光器等非线性装置中所产生的二阶或更高阶畸变产物。
在本发明的一个方面中,该低啁啾激光器是一在“C频带”1530纳米至1570纳米范围内操作的外部共振腔激光器。
在本发明的另一方面中,本发明提供一种用于减小模拟信号传输中畸变的预畸变电路,该电路将一输入调制信号分成两个电路径,其中一个是主要路径, 另一个是次要路径。一位于该次要路径上的预畸变放大器产生该输入信号的二阶或更高阶互调畸变产物。将由此产生的畸变或预畸变调整至在振幅上实质上等于而在符号上相反于被施加该信号的非线性调制装置中所固有的畸变。调整预畸变信号的振幅和相位,以匹配该非线性装置对畸变的频率依赖性。该些信号的相位由电路径之一中的一延迟或相位调整元件实施同步。然后,对主要和次要信号进行再结合,产生一包括互调产物畸变的单一调制信号。籍此,该预畸变电路通过消除非线性发射装置内固有的畸变而基本上将调制信号的传输线性化,从而使模拟信号适合在色散光纤链路上传输。
通过阅读包括详细说明在内的本发明揭示内容及亲身实践本发明,熟悉此项技术者极易发现本发明的其它目的、优点和新颖特点。虽然下文将参照较佳实施例来说明本发明,但应理解:本发明不仅限于该些较佳实施例。熟悉此项技术的普通技术人员通过阅读本文中的教示将会联想出本发明在其它领域中的其它应用、修改和实施例,而该些应用、修改和实施例皆属于本文所揭示并要求权利的发明范围内且本发明可具有与之相关的明显的实用性。
附图说明
结合附图参阅下文的详细说明将会更好更全面地理解本发明的该些和其它特点和优点。
图1是一本发明光学传输系统的极度简化的方框图;
图2是图1所示系统中使用的半导体激光器的横截面视图;
图3是先前技术中熟知的外部共振腔激光器的方框图;
图4a和4b是图1所示系统中使用的一预畸变电路的一当前较佳实施例的方框图;
图5是预畸变对一调制信号波型所产生作用的图解说明;及
图6是一用于调整激光器温度以保证激光器在一最小或最佳畸变操作点运行的负反馈回路的方框图。
本发明的新颖特点和特征陈述于随附权利要求中。然而,通过结合附图来阅读和参阅一具体实施例的详细说明可最佳地理解本发明自身及其其它特点和优点。
具体实施方式
下文将不阐述本发明的细节,包括其实例性方面和实施例。在附图和下文的详细说明中,使用相同的参考编号指代相同或功能上相似的元件,且该些参考编号旨在以极度简化的图示方式图解说明实例性实施例的主要特点。况且,图式即非意欲描绘出实际实施例的每一特点,也非意欲描绘出所绘示元件的相对尺寸,因此,该些图式未按比例绘制。
图1是直接调制模拟光学发射机方框图。图中显示有一模拟RF信号输入源101,例如一包含多个不同通信信号的宽带信号。RF输入被施加至执行……的RF调节电路102。RF调节电路102的输出被施加至一图4中将予以更详细阐述的预畸变电路103。预畸变电路103将一控制信号提供至一DC激光驱动器或控制电路104,该信号被施加至激光器105并控制光输出107。数字控制电路106也控制着控制电路104和激光器105。
图2是图1所示系统中所用的半导体激光器的一横截面视图,例如所示分布式反馈激光器(DFB);除去省略了光栅外,其他结构与法布里-珀罗(FP)激光器相同。
图3是先前技术中熟知的外部共振腔激光器的一方框图。该外部反射器在光学上即可为窄带也可为宽带,既可具有高反射率,也可具有低反射率。其可由镜面、衍射光栅、光纤布拉格光栅或任何其它合适的技术构建而成。激光器与该外部反射器之间的传播即可在自由空间内,也可局限在一波导内。
图4a和4b是图1所示系统中所用预畸变电路的一当前较佳实施例的极度简化的电路图,其中图4a是典型的RF预畸变电路,用于纠正由光纤色散诱发的二阶畸变,图4b是典型的RF预畸变电路,用于纠正激光器固有的三阶畸变。
现参见图4,一输入源信号12被馈送至一定向耦合器10内并被分成一主要电路径13和一次要电路径14。通常,该主要电路径上的信号的一部分在功率上实质大于该次要电路径上的信号。举例而言,可使用一11dB定向耦合器来实现此结果。该次要电路径在电路中依序包括:一畸变发生器15、一振幅调整块17、一“倾斜”或频率调整块19及一相位微调整块21。该些元件沿该次要电路径的顺序在不背离本发明的功能目的的前提下可有所变化。
在一实施例中,该次要电路径上的信号首先被馈送至该畸变发生器内,该畸变发生器的输出包括输入频率的互调畸变。可产生二阶及更高阶畸变。理想的情况是,通过消除、滤波或其它手段在畸变发生器中抑制基频。如此产生的互调产物在相位上与输入信号相反。此反转可在该畸变发生器内实现或使用一单独的反相器元件(未显示)来实现。
来自畸变发生器的畸变输出在振幅上与接收输出信号25的传输装置(图1中未显示)中预计的固有畸变的振幅相匹配。此匹配功能发生在振幅调整块17内,且此调整,举例而言,可通过一可变衰减器手动实现,或通过一自动增益控制元件动态实现。因此,振幅调整块17的输出包括该输入信号一小部分的互调畸变并且在振幅上实质等于且在符号上相反于接收预畸变电路输出信号25的非线性传输装置内固有的畸变。该输出或预畸变信号可有效减小非线性装置中不依赖于频率的畸变分量。
在次要电路径上产生预畸变信号通常涉及一相对于主要电路径的时间延迟。在主要路径与次要路径进行再组合之前,进行一调整来设定主要路径电信号相对于次要路径电信号相位的相对相位,这样可最佳地消除非线性装置内固有的畸变。该相位匹配由一外部延迟装置23在主要电路径上实施,而该外部延迟装置接收由定向耦合器10分割的信号13的主要部分。该时间延迟即可手动调整也可自动调整,一实例性延迟装置可是一简单的用于引入一合适延迟的选择长度的传输线。
图中图解说明一实际的线内预畸变器电路的实例性实施例,该电路依次包 括:一单块微波集成电路(MMIC)放大器30、一CATV混合放大器32、一RF反相器34及一位于一非线性装置(例如一激光器)前的可变电抗器36。该线内路径上的信号首先被馈送至一单端放大器内,例如一MMIC放大器,以主要产生实部的预畸变分量。MMIC放大器是RF电路设计中常使用的一种低成本组件。MMIC具有低成本优点,但是使用构建成混合集成电路或由离散组件构建而成的放大器也可以获得类似性能。MMIC放大器的输出包括放大的输入基频及输入信号频率的互调畸变。二阶互调产物主要由MMIC放大器产生。
来自MMIC放大器的畸变输出的实部分量的振幅较佳在振幅上与该非线性传输装置内预计的固有畸变的实部分量的振幅相匹配。然而,人们已发现MMIC放大器显现出仅与一非线性激光器的畸变特征成正比的畸变特征,并因此可能需要调整。对于相等的输入信号电平而言,来自MMIC放大器的畸变振幅通常大于非线性激光器所产生的振幅。为匹配畸变振幅,来自MMIC的输出信号电平必须低于激光器的输入信号电平。此需要在MMIC与该激光器之间使用一增益块。另外,可能还需要通过衰减器38在MMIC前引入一衰减,以使每个组件均以当前信号电平运行。
由于其成本低、广泛用于同轴分配网络中且线性输出在相关的输入频率之上,因此,CATV混合放大器32适合用于增强MMIC放大器的输出信号。CATV放大器在大多数低等至中等信号电平上产生可忽略不计的畸变。在高信号电平上,CATV放大器可显现畸变。然而,这不成问题,因为发生畸变的信号电平通常高于用于调制一典型非线性激光装置的相关信号电平。
可对衰减量和CATV放大器的增益进行必要的改变,以在输入调制信号中产生畸变产物。MMIC内的畸变振幅由输入信号的强度来决定。高信号强度时的畸变较大。因此,如果希望一较大的畸变,则少衰减该输入信号并减少CATV混合放大器的增益。同样,可调整MMIC放大器和CATV放大器上的偏压来改变畸变的相对振幅。通过更强劲地驱动MMIC放大器,可获得比输入信号较小情况下更大的畸变(相对于信号强度)。
如果必要,在RF反相器34中对CATV放大器调整至正确电平的预畸变信号进行反转,以提供一可用于消除该线性装置内实部畸变分量的信号。
预畸变的虚部分量在实例性实施例中主要由可变电抗器36产生;在一典型实施例中,可变电抗器36由一接地的电阻器68和二极管72构成。该可变电抗器具有一随电压而变的电容,可产生随输入信号的频率平方增大并与基频信号不同相90度的谐波畸变产物。当在不带有一电阻器的情况下使用该可变电抗器时,所产生的畸变是纯粹的虚部畸变,其振幅与畸变信号的频率成正比增加。增设该电阻器可引入一小的实部分量,可通过改变该电阻器的值来改变该实部分量。
通过改变一外部源提供至可变电抗器输入74的电压可控制该可变电抗器所产生的预畸变信号的虚部分量。当电压增大时,由于电容在反偏压下随电压发生该较小变化,因此产生较低的畸变。在较低电压下,该二极管显现较大畸变。如同振幅调整一样,该可变电抗器内的调整也可手动或自动进行。假设在该线内路径上有一简单的正弦波输入通过该可变电抗器,则该正弦波的峰在时间上会前移,而谷会后移。
虽然主要用于产生实部畸变分量,MMIC放大器可具有各种用于畸变的机理,其中某些机理可依赖于频率,而某些机理移动畸变的相位。不同的机理可在不同的偏压下起支配作用。通过在偏压输入76,78处改变放大器的偏压并在输入74处改变可变电抗器的输入电压,可在大多情况下对畸变进行必要的调整来补偿非线性装置。
人们发现,通常可在短短几分钟时间内完成对振幅、频率和相位的手动调整。人们要做的是实施适当的调整并同时观察非线性装置输出内的畸变。该调整谋求最大限度地降低非线性装置的最终畸变。最佳调整是当预畸变信号具有与非线性装置内固有畸变相同的值且预畸变恰好与畸变180度不同相时。也可通过使用(例如)一反馈控制电路自动实施此一调整。如果提前知晓一特定装置的非线性或该些非线性特征是可测量的,则可通过电子方法甚至更快地调谐 MMIC放大器、CATV放大器及可变电抗器的偏压。
一旦已设定线内电路径上预畸变信号的实部和虚部分量,信号即被输出至一非线性传输装置。
一实例性传输装置可以是一由该输出信号调制的半导体激光器或LED。
许多改变和修改对熟悉此项技术的人员是显而易见的,且该些改变和修改并不背离本发明的精神和范畴。举例而言,虽然本文以一用于调制一激光器或发光二极管的TV信号为背景来阐述及图解说明本发明,但其它诸如放大器等非线性装置也可具有此技术可基本消除的固有畸变。对主要和次要路径中信号的相对相位的微调在图示实施例中是在次要路径中进行的,但也可在实施粗调的主要路径中进行。微调较佳在次要路径中进行,其原因是主要路径中的此种延迟可能会对此路径造成不适当的阻碍。
图5图解说明预畸变对一调制信号波形的影响。特别地,其说明RF预畸变器如何作用于一非线性激光器来获得一线性化光输出。图的上半部分表示本发明处理一RF信号系统中的分量顺序,该图下半部分中的相应电压图表示作为输入的一函数的输出电压。
图6是一用于调整激光器温度以保证激光器在一最小或最佳畸变操作点下运行的负反馈回路的方框图。
图6图解说明靠近该激光器使用一温度控制器来控制该激光器的温度,以最大限度减小光纤链路接收机端存在的畸变。该温度控制器通常是一此项技术中熟知的Peltier热电冷却器。有数个与一激光器相关的物理参数随温度而变。在此等变量至关重要的应用中,无论外部环境温度如何,能够控制该激光器的实际温度是非常重要的。本发明使用一光电二极管监视该激光器的输出,并将该信号转变为一控制信号耦合至一激光器输出监视控制电路,该电路包括一耦合至该温度控制器的负反馈控制电路,以响应该激光器的输出调整该激光器的温度。
本发明技术和设备的各个方面可构建在数字电路中,或构建在计算机硬件、 固件、软件或其组合中。本发明的电路可构建在以有形方式包含在一机器可读存储装置中供一可编程处理器执行的计算机产品中,或构建在位于一网络节点或网址上可自动或根据请求下载至计算机产品的软件上。前述技术可由下述装置实施:例如,一单一中央处理器、一多处理器、一个或多个数字信号处理器、逻辑门的门阵列、或用于通过作用于输入数据并产生输出的方式执行一系列信号或指令程序来执行本发明功能的硬布线逻辑电路。该些方法可有利地构建在可执行于一编程系统上的一个或多个计算机程序中,该可编程系统包括:至少一耦合用于从一数据存储系统接收数据和指令并向该数据存储系统发送数据和指令的可编程处理器、至少一输入/输出装置及至少一输出装置。可使用一高级过程式或面向对象的编程语言,或汇编或机器语言(若需要)构建每一计算机程序;在任何情况下,该语言均可以是编译或解释语言。合适的处理器包括,举例而言,通用及专用微处理器。一般而言,一处理器将从只读存储器及/或随机存取存储器接收指令和数据。适合以有形方式包含计算机程序指令和数据的存储装置包括所有形式的非易失性存储器,其中包括:举例而言,半导体装置,例如EPROM、EEPROM及快闪存储器装置;磁盘,例如内部硬磁盘及可装卸式磁盘;磁光盘;及CD-ROM光盘。前述任何装置均可由专门设计的专用集成电路(ASICS)进行补充或含纳于该些专用集成电路中。
应了解,上述每一元件或两个或更多个元件也可有效应用于不同于上述类型的其它类型的结构中。
虽然本文以一光学传输系统为实施例图解说明并阐述本发明,但本发明并不意欲受限于所示细节,其原因是在不以任何方式背离本发明精神的前提下可对本发明做各种修改和结构改变。
无需再做进一步分析,上述内容如此全面地揭示本发明的要旨,以使其他人通过应用现有知识即可在不省略从先前技术角度看合理构成本发明一般或特定方面的基本特征的前提下轻易地将本发明修改应用于各种应用中,因此,此类修改应该并且拟涵盖在随附权利要求的等效意义和范围内。
Claims (28)
1.一种用于产生一调制信号供在一色散光纤链路上发送至一远距离接收机的光学发射机,其包括:
一输入,其用于接收一宽带模拟射频信号输入;
一具有一外部共振腔的半导体激光器,其用于产生一供在一光纤上发送的光学信号;
一调制电路,其用于使用所述宽带模拟射频信号直接调制所述激光器,所述调制电路包括一预畸变电路以减小所述光纤链路接收机端处存在的信号内的畸变;及
一连接至所述半导体激光器的输出的输出功率调整构件,所述输出功率调整构件用于调整所述半导体激光器产生的所述光学信号的平均输出功率,以使所述功率低于所述色散光纤链路的受激布里渊散射阈值的功率。
2.如权利要求1所述的光学发射机,其中所述激光器的光输出波长位于1530至1570纳米范围内。
3.如权利要求1所述的光学发射机,其中所述宽带模拟射频信号输入具有一大于一倍频的带宽并包括多个不同的信息载送通道。
4.如权利要求1所述的光学发射机,其中所述预畸变电路补偿所述激光器的非线性响应。
5.如权利要求1所述的光学发射机,其中所述预畸变电路补偿在所述接收机端处测定的因通过一色散光纤链路发送一调频光学信号而产生的畸变。
6.如权利要求1所述的光学发射机,其中所述预畸变电路可进行选择性调整,以依据所述链路的长度补偿由所述色散光纤链路产生的畸变。
7.如权利要求1所述的光学发射机,其中所述预畸变电路在工厂设定至一预定值,以依据所述链路的长度补偿由所述色散光纤链路产生的畸变。
8.如权利要求1所述的发射机,其中所述调制电路进一步包括一低频信号调制器,以增大所述色散光纤链路的受激布里渊散射阈值。
9.如权利要求1所述的光学发射机,其中所述预畸变电路包括沿所述宽带模拟射频信号路径依序设置的多个线内畸变产生电路元件,以便通过加性组合来自线内畸变产生电路元件组合的畸变分量而在所述电路内合成一适当的实部和虚部畸变,所述实部和虚部畸变达到足以实质上消除或减小因所述激光器非线性而产生的畸变的程度;且其中在所述线内畸变产生电路元件内所述宽带模拟射频信号不分离成一基频信号路径和一单独不同的畸变产生路径。
10.如权利要求1所述的光学发射机,其中所述调制电路包括一AM-VSB调制器。
11.如权利要求1所述的光学发射机,其中所述调制电路包括一正交调幅器。
12.如权利要求11所述的光学发射机,其中所述输出功率调整构件是一相位调制器。
13.如权利要求11所述的光学发射机,其中所述输出功率调整构件是一铌酸锂相位调制器。
14.如权利要求11所述的光学发射机,其中所述输出功率调整构件是一压电相位调制器。
15.一种用于产生一调制光学信号供在一色散光纤链路上发送至一远距离接收机的光学发射机,其包括:
一输入,其用于接收一宽带模拟射频信号输入;
一半导体激光器,其用于产生一供在一光纤上发送的光学信号;
一调制电路,其用于使用所述宽带模拟射频信号直接调制所述激光器;
一接近所述激光器的温度感测器,其用于监视所述激光器的温度;及
一耦合至所述温度感测器的控制电路,其用于响应所述激光器的一光学输出特征调整所述激光器的温度。
16.如权利要求15所述的光学发射机,其中所述激光器的输出特征是作为所述激光器输入信号的函数的所述光学信号的线性关系。
17.如权利要求15所述的光学发射机,其中所述激光器的输出特征是通过以下方式测得:使用一导频音作为所述激光器的一输入并在所述输出处检查互调产物,以确定作为所述激光器输入信号的函数的输出信号的线性。
18.如权利要求15所述的光学发射机,其中所述激光器是一外部共振腔激光器。
19.如权利要求15所述的光学发射机,其中所述激光器的光输出波长位于1530至1570纳米范围内。
20.如权利要求15所述的光学发射机,其中所述宽带模拟射频信号输入具有一大于一倍频的带宽并包括多个不同的信息载送通道。
21.如权利要求15所述的光学发射机,其中所述调制电路进一步包括一低频信号调制器,以增大所述色散光纤链路的受激布里渊散射阈值。
22.一种用于产生一调制光学信号供在一色散光纤链路上发送至一远距离接收机的光学发射机,其包括:
一输入,其用于接收一宽带模拟射频信号输入;
一半导体激光器,其用于产生一供在一光纤上发送的光学信号;
一调制电路,其用于使用所述宽带模拟射频信号直接调制所述激光器;及
连接至所述半导体激光器输出的输出功率调整构件,该构件用于调整所述半导体激光器产生的光学信号的平均输出功率,以使所述功率低于所述色散光纤链路的受激布里渊散射阈值的功率。
23.如权利要求22所述的光学发射机,其中所述输出功率调整构件是一相位调制器。
24.如权利要求22所述的光学发射机,其中所述输出功率调整构件是一铌酸锂相位调制器。
25.如权利要求22所述的光学发射机,其中所述输出功率调整构件是一压电相位调制器。
26.如权利要求22所述的光学发射机,其中所述激光器是一外部共振腔激光器。
27.如权利要求22所述的光学发射机,其中所述激光器的光输出波长位于1530至1570纳米范围内。
28.如权利要求22所述的光学发射机,其中所述宽带模拟射频信号输入具有一大于一倍频的带宽并包括多个不同的信息载送通道。
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JP (1) | JP2005269658A (zh) |
KR (1) | KR20060044429A (zh) |
CN (1) | CN1694385B (zh) |
TW (1) | TWI357229B (zh) |
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CN1694383A (zh) | 2005-11-09 |
US7466925B2 (en) | 2008-12-16 |
US20050271396A1 (en) | 2005-12-08 |
JP2005269658A (ja) | 2005-09-29 |
TW200608719A (en) | 2006-03-01 |
KR20060044429A (ko) | 2006-05-16 |
TWI357229B (en) | 2012-01-21 |
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