WECS, Laguna Beach, and Meeting John Pendry
David Vier, Willie, Syrus and I completed the poster maybe a day before the
Workshop on Electromagnetic Crystal Structures (WECS) in Laguna Beach that
Eli Yablonovitch had invited me to. From the agenda, I saw that John Pendry
was going to be there, and I was really interested to see what he would think
about our approach to the wire medium. Shelly, who was also going up to the
meeting, suggested we meet with John together, so we agreed on a time to meet
at the poster session.
It was the first time I'd ever met John; he was incredibly good natured and
extremely approachable. He graciously agreed to look over our poster, and
after just a few minutes confirmed that we had an equivalent way of arriving
at a microwave plasmonic medium. He was actually amused by the loop-wires
that we had made.
"Who made all of those loops?" John wondered.
"Syrus and Willie, a couple of graduate students in our lab."
"Oh dear!" John kind of laughed. "Seems like a lot of work. I think I'll
stick with my thin wires, thank you very much," he added, jokingly.
Thin wires, loop wires, it didn't matter to me; we had done it! We now had a
plasmonic medium that was easy for us to make and measure, and which also had
John Pendry's endorsement. I was completely satisfied.
"By the way, are you coming to my talk?" John asked. "I think you’ll find it
very interesting as well."
Shelly and I, of course, attended all the talks at the meeting, and John's
talk was top on our list. And the timing could not have been better: John was
about to give his first talk on the split-ring medium.
WECS，Laguna海滩，与John Pendry见面
可能是Eli Yablonovitch邀请我在Laguna海滩举办的电磁晶体结构研讨会
Workshop on Electromagnetic Crystal Structures（WECS）的前一天，David Vier,
Willie, Syrus和我完成了海报。从会议议程中，看到John Pendry也即将参加，我真的
很感兴趣看他会怎样看待我们处里导线介质的方式。Shelly也北上参加这个会议，他建议
我们与John见面，所以我们约定了一个时间在海报会议上见面。这是我第一次见过John;
他是非常善良且极为平易近人。他欣然地同意看看我们的海报，并且在短短的几分钟后确
认我们用相同的方法得到微波电浆介质的。他实际上也是假设回路和线圈的方式跟我们所
做的一样。
“谁做的所有这些回路的？” John好奇地问。
“Syrus and Willie，我们实验室的一对的研究生。”
“哦，天啊！”John式的笑了起来。“似乎是一个大量的工作，我想我会坚持我的细导
线，非常感谢你，”他开玩笑地补充说，。
这些细导线，电线圈，对我并不重要; 我们已经做到了！我们现在有对我们来说容易制造
和测量的电浆介质，并且也有John Pendry的认可。我完全满意。
“顺便说一下，你能来我谈谈吗？” John问。“我想你将也会觉得非常有趣的。”
当然，Shelly和我，在所有参加会谈的会议上，能和John的谈话是我们名单上第一名。
时间点再也不可能更好了：John正要给裂环介质上的第一次演讲。
I had started playing around with the wire medium to create something that
would have a negative ? at microwave frequencies, with a goal of emulating
the nanoparticles we were working with in our microscopy experiments. I had
not thought beyond that possibility.
But John's talk changed that. He was now interested in trying to create
artificial magnetism, and proposed a series of new structures, from
conductors rolled up into little tubes like "Swiss rolls," to little, flat,
rings with gaps in them, he called "split-ring resonators." Though there were
no inherently magnetic materials in these structures - they were pure
conductors - John predicted they would have a magnetic resonance, with a
regions where the effective permeability, μ could be controlled, with large
positive values or even negative values.
我已经开始玩弄在微波频率波段的光与导线介质所产生的东西，会产生负的？目标是
模拟我们在显微镜下工作与奈米粒子。我还没有想过超越这种可能性。
但John的谈话改变这一切。他现在有兴趣制造人工磁性，并提出了一系列新的结构，
从导线卷成如“瑞士卷”，以小，扁平，环中有缝隙，他所谓的“裂环共振器“。虽然在
这些结构没有本质上的磁性材料- 他们是纯粹的导体 - John预言他们将有磁共振，与那里
区域的有效磁导率μ可以被控制，以大正值或甚至负值出现。
"A negative μ?! That's impossible! What does that even mean?" Shelly, who
was sitting next to me during John's talk, was leaning over with a shocked
look on his face. "John's crazy! There's no such thing as negative μ. I've
never heard of it."
I thought about it. We all accepted that ? could be negative. Why should a
negative μ be impossible? What was really exciting was the fact that John
was now proposing an artificial magnetic structure that could control μ.
With the wires, that could control ?, and the rings that could control μ,
you could create materials with completely arbitrary electromagnetic
properties. That's what was really amazing.
“负μ？！那是不可能的！这是什么意思啊？” 在John的谈话中，Shelly就坐在我旁
边，俯身并在他的脸上用震惊的表情。“John太疯狂了！我从来没有听说过有这样作为
负μ的东西。”
I thought about it. We all accepted that ? could be negative. Why should a
negative μ be impossible? What was really exciting was the fact that John
was now proposing an artificial magnetic structure that could control μ.
With the wires, that could control ?, and the rings that could control μ,
you could create materials with completely arbitrary electromagnetic
properties. That's what was really amazing.
I returned to UCSD, fired up about demonstrating artificial magnetism. Shelly
was also now somewhat interested, because he had believed that a negative μ
was impossible, and was curious to see if this impossible material could be
made. So, we were both motivated in our own ways to continue building
microwave structures, at least for a little while longer.
Also, I'm pretty sure, Shelly and I were the only ones interested in building
the artifici al magnetic structures at that point.
我想过这个问题。我们都接受了？可能是负的。为什么负μ应该是不可能的？真正令
人兴奋的事实是John现在正建议一个可以控制μ的人工磁结构。与导线一样可以控制负的
介电常数ε？而且可控制μ的环，你可以创造完全任意电磁特性的材料。这是非常令人惊
奇的。
我回到了加州大学圣地亚哥分校，启动了演示人工磁性。Shelly是现在也有点兴趣，
因为他认为一个负μ的磁导率是不可能的，并且很好奇想看看这个不可能的材料被制造出
来。
所以，至少有一段时间我们是出于自己的方式来继续建造微波结构，。
另外，Shelly和我唯一的兴趣是建造人工磁结构。这一点我相当的肯定。
You see, the WECS was a conference about photonic crystals. And, the vast
majority of people working on photonic crystals are, naturally, interested in
photonics, which usually is about visible light or light at near-infrared
wavelengths. Probably ninety-nine percent of the people at the workshop had
no interest in microwaves. When it came time for questions, there was an
uncomfortable silence, except for one person. That person was George Merkel,
a researcher from the Army Research Laboratory.
George came across as a little annoyed. "Everything you're talking about has
been done before," George announced. "These ring structures, the wire
structures - they were all looked at in the 40s and 50s, mostly by Army
researchers. It's interesting stuff, but it didn't go anywhere. There was
some thought of using the wire medium as a way to model wave propagation in
the Ionsphere, but it didn't catch on. Some people made lenses and other
quasi-optical devices."
你看，Workshop on Electromagnetic Crystal Structures (WECS)是一个关于光子
晶体的学术会议。而且，绝大多数的人们的工作的主要都是光子晶体，自然地，感兴趣的
是光子，通常大约是可见光或是在近红外线波长的光。也许在研讨会上99％的人对微波毫
无兴趣。当来到问问题的时间，有一种令人不舒服的沉默，除了一个人。
那人是George Merkel，一个来自美国陆军研究实验室的研究员。George看起来有点
恼火。“你说的每一件事在之前早已经做过了，” George公布。
“这些环状结构，导线结构 –大多是被陆军研究人员，它们在1940年代和1950年代都
曾看过了。这是很有趣的东西，但它并没有任何用途。利用导线介质有些被思考做为在电
离层波传播的模型一种方式，但它并没有流行开来。有些人做镜头和其他准光学元件。“
It turned out that George Merkel was right! He forwarded a big stack of old
papers to Eli, who didn't have time to read them all and who then sent them
on to me. The wire medium had indeed been discovered by Rotman, and the
split-ring resonator as a magnetic material had been described by
Scheulnekoff. In fact, their approach was an engineering one that was much
closer to the way I was now thinking about these things.
One of the difficulties of all of those papers, though, was that the
effective medium theories were rough and approximate, having been done before
there were full-wave numerical simulators that would be able to give precise
results. The formulas, even if approximate, were difficult to derive and
cumbersome, sometimes expressed as infinite sums that would have to be
truncated. Every time you would change the geometry, even a little, you might
need to derive entirely different formulas. It was daunting! I could see how
difficult it might have been to arrive at a well-designed artificial
electromagnetic material using the approximate analytical formulas that gave
the only viable design path at the time.
John Pendry's work, while an independent rediscovery of sorts, had cast
artificial materials in a new light. It was the perspective of a physicist
rather than an engineer, and that opened up new opportunities.
原来，George Merkel是对的！他转发的一大堆旧论文一大叠给Eli，他没有时间阅读
所有这些论文，然后Eli把它们寄到我这里。Rotman确实已经发现导线介质，并且做为磁
性材料的裂环共振器的已经被Scheulnekoff描述。其实上，他们是一个工程的方法，这就
更接近我现在对这些事情的想法。
One of the difficulties of all of those papers, though, was that the
effective medium theories were rough and approximate, having been done before
there were full-wave numerical simulators that would be able to give precise
results. The formulas, even if approximate, were difficult to derive and
cumbersome, sometimes expressed as infinite sums that would have to be
truncated. Every time you would change the geometry, even a little, you might
need to derive entirely different formulas. It was daunting! I could see how
difficult it might have been to arrive at a well-designed artificial
electromagnetic material using the approximate analytical formulas that gave
the only viable design path at the time.
John Pendry's work, while an independent rediscovery of sorts, had cast
artificial materials in a new light. It was the perspective of a physicist
rather than an engineer, and that opened up new opportunities.
然而，所有这些论文其中之一的困难是有效介质理论是粗糙的和近似的，之前就已经
有全波数值模拟器能够提供精确的结果。这些公式，即使是用近似，也是难以推导和繁
琐，有时候表示为无穷求和将必须被截断。每一次你会改变的几何形状，即使是一点点，
你可能需要推导完全不同的公式。它是令人望而生畏的！我能看到这些有多么困难它可能
到达一个精心设计的人工电磁材料采用近似解析的公式给出了设计时的唯一可行的路径。
John Pendry的工作，当他各式各样的独立重新发现，已经给人工材料一种新的观点，这
是从物理学家的角度而不是从工程师的角度来看，这开辟了新的机会。