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Apr 17

From quantum Zeno effect to all optical switch, part II.

By Frank Kuo CLEO Conference, CLEO: Applications, QELS Conference No Comments »
This post originally appeared on CLEO 2011 by Frank Kuo and is reproduced with permission from its author.

In the last blog, we took a trip starting from quantum Zeno effect and reached to one of its applications — all-optical switch — at a quick pace. This time, we will look into more phenomena that researchers use in order to achieve this all-optical switch future.

We discussed about photonic crystals (PCs) and their versatility in a recent blog. We learned that by changing the patterns of the PCs, it is able to select which color of light that can travel within it or be rejected. While the patterns play the crucial role in PCs, we have to realize that it is the modulation of the refractive index produced by the patterns that give PCs their unique physical properties. With this being said, it is not difficult to understand that if the refractive index of the material that PCs are made of can be changed, we are able to affect (or tune) PCs’ properties. This is exactly what researchers are trying to do recently:

Considering the silicon PC shown in figure 1a, there are two colors of light allowed to propagate in it (mode c and mode s). Now, it is known that putting some free electrons in the conduction band of Si would change its refractive index. To use this feature, researchers shine this PC with some light (pump) such that a few electrons in the Si can be kicked to the conduction band. Changing the refractive index shifts the center frequencies of mode c and mode s directly. In addition, since PC is so sensitive to its refractive index, just a few hundred fJ of energy is required to tune the transmittance property of the PC. The all-optical switch is then realized by the following: Let’s input two colors of light into the PC — one is very close to mode s and one is right at mode s (figure 1b). Without the additional pumping light, mode s is transmitted. With the pump, mode s is suppressed and the other color now is able to transmit since the transmittance property is shifted. So by pump-on/pump on, we will have different colors of light coming out — an all-optical switch, as we expect.

Figure 1. an all-optical switch based on a silicon PC. (a) The structure and the transmittance curve of this specific PC. (b) with/without pump, the transmittance of the PC is shifted. Here we use mode s as an example. Courtesy of T. Tanabe, M. Notomi, S. Mitsugi, A. Shinya, and E. Kuramochi on APL 87 151112 (2005).

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Apr 11

From quantum Zeno effect to all-optical switch, part I.

By Frank Kuo CLEO Conference, CLEO: Applications, QELS Conference 3 Comments »
This post originally appeared on CLEO 2011 by Frank Kuo and is reproduced with permission from its author.
Needless to say, scientists have been puzzled and fascinated by the quantum nature of the physical law for more than a century. The history of science is all over it and evolves with it. Having this in mind, it is very reasonable to see that the Science magazine has named the discovery of the quantum machine as the most significant scientific advance of 2010. It is the first quantum mechanical resonator that can actually be seen by bare eyes and deserves another detailed blog by itself.

How about in the optical world? Have we successfully implemented or utilized the quantum nature of materials for cool applications? The exciting answer is YES, and we will be looking at some of them in this short blog:

Let’s start from one of the most bizarre behavior that quantum mechanics can do – Quantum Zeno Effect. It states that if your observation of an event is frequently enough, its decay to the natural state of equilibrium will be affected significantly, either being slowed down, frozen, or accelerated. In fact, scientists call it anti-Quantum Zeno Effect, if the process is being accelerated (by the way, you will be able to hear the talk from its explorer — Gershon Kurizki in CLEO 2011: QELS Fundamental Science).

The name “Quantum Zeno effect” adopts a broader meaning when it enters the optical world. We now use this term to describe manipulating the evolutions of the populations of different quantum states (or photons with different colors) by external perturbation.

If you feel the aforementioned is hard to digest, I promise the following will be not. We will be looking at some real examples and these are aiming for a high goal — all-optical switches. If you wonder why all-optical switch is important, just think about how hot your CPU can get most of the time and how fast light can travel compared with electrons.

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Apr 07

Candy store for Lasers and Electro-Optics

By JamesVanHowe CLEO Conference, CLEO: Applications, QELS Conference No Comments »

Program Chairs Video Interviews: From CLEO website

This post originally appeared on Jim’s Cleo Blog and is reproduced with permission from its author.

If you haven’t been to the CLEO 2011 conference website in the last week (or even if you have), it is worth taking a look at the video interviews with the programming chairs. There are 11 videos addressing the chairs’ top picks for talks, their views of trends in optics, advice for conference goers, and their impressions of CLEO’s scope and impact for optics research.

In the interviews, the chairs spoke in unison of how CLEO is unique among optics conferences in its breadth of research, particularly spanning basic research to market-ready products. On one hand, you can find talks on fundamental quantum mechanics such as those in the Symposium on the Zeno Effect in Optoelectronics and Quantum Optics whose subject delves into the fundamental nature of measurement. The quantum Zeno effect (or paradox) refers to inhibiting quantum transitions by frequent, repeated measurement. On the other hand, in session “Laser Micro and Nano Structuring”, in CLEO: Technology and Applications: Industrial, Guido Hennig from Daetwyler Graphics AG, will give an invited talk, AMD4, “Laser Microstructuring and Processing in Printing Industry,“ discussing the use of high-power fiber lasers for engraving printing plates, as well as high-speed laser modulation for laser-induced ink transfer. In one of the video interviews, Harold Metcalf, from SUNY Stoneybrook, CLEO:QELS Fundamental Science General Co-Chair, aptly characterizes the wide scope of such interesting topics. “Looking over the program and the titles of the sessions, I feel like a kid in a candy store- with unlimited funds, but limited time. It’s impossible to do everything,” quips Metcalf. To view the “candy store” selection, which I highly recommend as a way of searching for interesting talks you might otherwise miss, go to the conference itinerary planner and click on “Search” and then the “Session Title” drop down menu. You’ll be overwhelmed, impressed, and excited.

Some of the specific goodies highlighted by the program chairs in the video-interviews were contributed papers and invited talks discussing UV LEDs, photovoltaics, nanoscale laser sources, metamaterials, broadband spectroscopy, and integrating optics on-chip….to view the entire original post, click here.

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