瑞士洛桑联邦理工学院(EPFL)的研究团队宣称找到一种简单的创新途径，只需轻松地切换至新的发射器，即可使现有网络中的光纤传输率提高10倍。根据EPFL的研究人员Camille Bres与Luc Thevenaz指出，采用奈奎斯特正弦脉冲，可在时域重迭且采用最小带宽的脉冲上为信息进行编码，从而实现最大化的光纤传输率。
由于脉冲能尽可能减少符号间的干扰，其他研究团队也试图产生奈奎斯特正弦脉冲，但最后还都得再采用更复杂的讯号产生器。Camille Bres与Luc Thevenaz则声称其光谱合成技术能更有效地操作，而且也是唯一能简单建置商用光纤发射器的技术。
“我们合成出一种能带来完美脉冲波形的频谱。透过使用简单的强度调变器产生一组光谱线，有规率地留出间隔，并显现完全相同的振幅与相位。这是在时域中自动产生的正弦脉冲波形，”Luc Thevenaz表示，“这非常简单明了，但以前都没人想过要这样做。”
以奈奎斯特脉冲编码10倍信息容量的概念图
Source：Jamani Caillet / EPFL3O3esmc
EPFL的研究团队宣称，在实验室环境下，雷射与调变器可产生较广的频谱脉冲，正好是产生99%完美奈奎斯特脉冲的所需的各种条件。
研 究人员们表示，对于光纤芯片制造商来说，设计一款能实现其编码技术的发射器芯片，将会是更简单明了的做法。其中应该要能包括“产生方形频谱所需的调变器， 以及一组短延迟线与调变器，以产生数据序列，同时交错于暂存序列中，以提高数据传输率，”Luc Thevenaz表示。
EPFL研究人员Camille Bres与Luc Thevenaz宣称可使传统光纤中的信息量提高10倍。
Source：EPFL3O3esmc
根据研究人员表示，由于这项频谱合成技术能够产生矩形的频梳锁相，因而也可能用于其他领域，包括微波光子学、光储存以及全光采样等。
本文授权编译自EE Times，版权所有，谢绝转载
编译：Susan Hong
参考英文原文：Transmitter Chip Boosts Optical Fiber Capacity 10X，by R. Colin Johnson
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Transmitter Chip Boosts Optical Fiber Capacity 10X
R. Colin Johnson
PORTLAND, Ore. — Increase fiber optic capacity in existing networks by 10-times just by switching to a new kind of transmitter -- that's the claim of a research group at EPFL (école Polytechnique Fédérale de Lausanne, Switzerland). Using sinc-shaped Nyquist pulses, information can be encoded on pulses that overlap in the time domain and use a minimum of spectral bandwidth, thus maximizing optical capacity, according to the EPFL research team of Camille Brès and Luc Thévenaz.
Other groups have tried to produce Nyquist sinc pulses to minimize inter-symbol interference, but had to resort to complex signal generators. Brès and Thévenaz claim their spectral synthesis technique works better, plus is the only one that will be easy to implement for commercial optical transmitters.
"We synthesize a spectrum that gives the perfect pulse shape. We do it by using a simple intensity modulator to generate a set of spectral lines, regularly spaced and showing exactly the same amplitude and the same phase. This gives automatically in the time domain the sinc pulse shape," Thévenaz told us. "This is very simple and straightforward, but nobody thought to do it this way before."
Artists conception of Nyquist pulses encoding 10-times more information (Source: (C) Jamani Caillet / EPFL)
Artists conception of Nyquist pulses encoding 10-times more information (Source: ? Jamani Caillet / EPFL)
The EPFL team claims that in the lab a laser and a modulator -- to produce wide-spectrum pulses -- are all that's needed to generate Nyquist pulses that are 99 percent perfect.
The researchers claim that designing a transmitter chip that realizes their encoding technique should be a straightforward exercise for optical chipmakers, and would include "the modulators required to generate the square shaped spectrum and a set of short delay lines and modulators to generate data sequences and to interleave them in the temporal sequence, to increase the data rate," said Thévenaz.
EPFL research team of Luc Thevenaz and Camille Bres claim to pack 10-times as much information in conventional optical fibers. (Source: EPFL)
EPFL research team of Luc Thévenaz and Camille Brès claim to pack 10-times as much information in conventional optical fibers.
(Source: EPFL)
The spectral synthesis technique -- which produces a rectangular-shaped, phase-locked frequency comb -- could also be useful in other fields, according to the researchers, including microwave photonics, light storage, and all-optical sampling.
