Biannual-Published Newsletter of the
ISSUE
04
DEPARTMENT OF ENGINEERING
Fall 2009
University of Nicosia
Get Tuned
Organic Light Emitting Diode (OLED) Technology Message from the Head
By Dr George Gregoriou
In this issue... Organic LED Technology Cloud Computing All-Optical Switching employing MEMS Diffraction of light and Blu Ray Discs
First of all, I would like to wish you a
Department Seminar
Happy, Healthy and Prosperous New
device which is usually 100 to 500 nanometers thick. There are designs with two or with three layers of organic compounds. The most common is the two-layer version.
Year. As the new Head of the Department of Engineering, I will do my best to serve the Department, both faculty and students. Our Department is going through its third year of life as a part of the University of Nicosia. During the last couple of years, a lot of progress has been achieved with the hard work of the
previous
Head
Department, Prof. the
rest
of
of
the
Polycarpou, and
the
faculty.
The
Department has grown both in terms of number of students and number of faculty members. The academic pathways
of
offered, Engineering
the
two
programs
namely,
Computer
and
Electronics
Engineering, have been restructured and enriched in order to reflect the modern trends in the corresponding fields of study and meet international standards.
The ECPU will soon be
evaluating the above programs, as well as all the programs of our university, in order to give its final approval. I will end my short message with something that I believe is very important for all of us to remember: it is difficult to reach a goal in life but is even more difficult to preserve what has been achieved. Finally, I would like to remind the students of the Department of Engineering that all faculty members are there to assist them through their studies and discuss with them any problems they may encounter.
Best Regards Dr. Marios Nestoros
Imagine having a high definition TV that is 80 inches wide and a few millimeters thick, consumes less power than most TVs on the market today and can be rolled up when not in use. What if you could have a heads-up display in your car? How about a display monitor built into your clothing? These devices may soon be possible with the help of an emerging technology called organic light-emitting diodes (OLEDs). OLEDs are solid-state devices composed of thin films of organic molecules that create light with the application of electricity. OLEDs can provide brighter, crisper displays on electronic devices and use less power than conventional light-emitting diodes (LEDs) or liquid crystal displays (LCDs) used today. OLED technology will emerge as a leading next-generation technology for displays and lighting. It is already used in mp3 players, cellular phones, digital cameras, television screens, computer displays and many other products. It can also be used as a light source for general space illumination. OLED Technology An OLED is a solid-state semiconductor
The five main parts of OLED are substrate, anode, cathode and two organic layers. The substrate should support the OLED and can consist of glass, foil or clear plastic. The anode is usually transparent and removes electrons, the cathode does exactly the opposite, it injects electrons. Depending on the type of OLED used, the cathode can be transparent or not. The organic layers are a conductive layer and an emissive layer. The conductive layer is made of organic plastic molecules (one conductive polymer used in OLEDs is polyaniline) and the emissive layer from different organic plastic molecules (one polymer used in the emissive layer is polyfluorene). These molecules transport electrons from the cathode. This is the part where light is emitted. …continued at page 5 References: http://www.howstuffworks.com http://www.wikipedia.org http://www.about‐oled.com
Did you know that … At the heart of all personal computers sits a microprocessor that controls the logic of almost all digital devices, from clock radios to fuel-injection systems in automobiles. The most important characteristic that defines microprocessors’ performance is the clock speed. Given in gigahertz (GHz), the clock speed determines how many instructions per second the processor can execute. For example, a 64-bit microprocessor that runs at 3GHz is more powerful than a 32-bit microprocessor
that
runs
at
2.8GHz. If you think overclocking sounds like an ominous term, you have the right idea. Basically overclocking means to run a microprocessor faster than the clock speed for which it has been tested
and
approved.
Over-
clocking is a popular technique for getting a little performance boost from your system, without purchasing any additional hardware. Because of the performance boost overclocking, is very popular among gamers. Most times overclocking will result in a performance boost of 10 percent or less. For example, a computer with an Intel Core Duo
processor
running
at
2.8GHz could be configured to run at speeds equivalent to a Core Duo 3GHz processor by increasing the bus speed on the motherboard. Overclocking will not always have the exact same results. Two identical systems being overclocked most likely will not produce the same results. One will usually always overclock better than the other. To overclock your CPU you must be quite familiar with computer hardware, and it is always a procedure conducted at your own risk!
Cloud Computing By Dr Ioannis Kyriakides Imagine playing games like World of Warcraft or Call of Duty on your cell phone or a handheld game console. Or if you are even geekier, imagine running your Matlab assignment on your cellphone one last time before submitting it. You may think that all these could be possible twenty years from now. The above applications require so much processing power that can only now be provided by sophisticated game consoles or powerful PC's with a very good graphics card. How could we then possibly use these applications on a tiny cellphone? The answer is cloud computing.
The tough job will be handled by the almighty cloud!
What is the catch, you may ask. There are a few actually. One is quite reasonable: someone has to pay for the host supercomputers out there on the cloud and their operational cost. And the ones to pay are, of course, the users. The host will provide the software and computations as a service that can be used for a fee. The overall cost for the user will, however, be less than when using current technology. Paying for a simple PC or cellphone and the required services will be less expensive than buying a powerful enough computer or gadget. Is there another We are all familiar with the computing catch? The use of the cloud will mark part of the term. But what is with the the end of software piracy. Since the cloud? Well, the cloud is just a figura- most important part of the software tive term for the internet. With the will be installed on the host, there cloud computing concept, a small piece simply won't be any software to pirate. of hardware, such as a cellphone or a You may have already realized that very simple PC, will assign a computa- there is a large group of people being tionally expensive task to a more pow- unhappy with the cloud computing erful compuconcept. And tational mathese are not chine by comonly the pimunicating the rates out there task via the but also the internet. Theones who view refore, during large corporagame play, tions such as the cellphone Microsoft, and may transmit yes, Issue’s Google asQ& This the player's ones trying to moves to a take control out host supercoof the people’s mputer. Then hands and make the host, will more profit out Courtesy http://en.wikipedia.org/ easily and of it. speedily calculate the outcome of the hero action and the rest of the game pa- In spite of all the objections, cloud rameters and render the graphics. Next, computing seems like a really interestthe host will transmit the resulting video ing concept that may in the near fuin a compressed from back to the cell- ture provide us with access to more phone. Thus, a game with elaborate gra- computational power, more cheaply phics can be played with a simple termi- and efficiently. nal. The same principle will apply with any other software that we need to run. Therefore, in the near future, using cloud computing, we will be able to run complex applications without the need to buy expensive PC's or game consoles with large computational muscle.
To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the glass is twice as big as it needs to be.
EYE ON TECHNOLOGY
All-Optical Switching employing MEMS By Dr Antonis Hadjantonis The rapid explosion of IP has brought about an ever-increasing need for speed and transport capacity which only optical networking employing wavelength division multiplexing WDM technology seems capable to satisfy. This is because electronic speeds are currently limited to about 40Gbps while the Dense WDM (DWDM) optical fiber is nowadays discussed of transmitting in the order of Pbps (millions of Gbps). To this end, optical networking has evolved from its first generation, the simple P2P optical communication link, to the third generation alloptical reconfigurable, intelligent and fault-tolerant network. In such a network, data plane remains in the optical domain from source to destination, which implies that all-optical switching is performed at intermediate nodes. These nodes are also known as Optical Cross-Connects (OXCs). A typical OXC with two wavelengths (位1 and 位2) and three input/output ports is shown in figure below.
Optical switching can be performed by various technologies like semiconductor optical amplifiers (SOA), thermo-optic switches, electro-optic switches, bubble-based waveguide switches, and microelectromechanical system switches (MEMS). MEMS are miniature mechanical devices which are typically fabricated on silica substrates and employ electromechanical functionalities (very much similar to the integrated cir-
cuits, or ICs). In the context of light switching, the MEMS switches mean arrays of miniature movable mirrors fabricated on silicon. Their dimensions range in the millimeters and they can be deflected from one position to another by means of electronic actuator techniques (like electromagnetic or electrostatic methods). MEMS optical switches can be 2dimensional (2D) or 3-dimensional (3D) with the latter having sizes that exceed 10,000 ports.
Diffraction of light and Blu Ray Discs By Dr Marios Nestoros A Blu-ray Disc is an optical disc storage unit similar to a DVD or a CD disc, but with much higher storage capacity. The improved design of the Blu-ray was made feasible due to the fabrication of diode lasers,
which
are
tiny
and
cheap, able to emit at 405 nm (blue colour) as compared to 650 nm (red) for conventional DVD and CD systems. The spot size at which a beam of light can be focused is determined from diffraction (the spreading of a wave while passing through an aperture) and is thus proportional to wavelength. By using smaller light spot sizes we can inscri-
The deflection of the mirrors provides connectivity from an input port to an output port as seen in the figure above. This entails that the position of the mirror must be decided, assumed and tested a priori. That is why before any data can flow in the network, the whole circuit from the ingress to the egress node must be setup (i.e. we are dealing with a circuit switching network). 3D MEMS switches configure, stabilize and test quite fast (in about 10ms) and can provide low insertion losses (~5dB), cross talk (x-talk) losses of 55dB and polarization dispersion losses of approximately 0.5dB.
be information on smaller regions on the disc and hence increase its storage capacity. In practice, a Blu-ray system using the 405 nm laser line can achieve spot sizes around 0.30 micrometers, half the spot size achieved with DVD systems and around five times smaller than that achieved by a CD system as can be seen in the figure below. As a result, a single-layer Blu-ray
disc,
which
is
roughly the same size as a DVD, can hold up to 27 GB of data. That is more than two hours of high-definition video or about 13 hours of standard video. A doublelayer Blu-ray disc can store up to 50 GB, enough to hold about 4.5 hours of highdefinition video or more than 20 hours of standard video. Resources http://electronics.howstuffworks.com/bluray3.htm http://en.wikipedia.org/wiki/Blu-ray_Disc
In the heart of GPS Triangulation Improbable as it may seem, the whole idea behind GPS is to use satellites in space as reference points for locations here on earth. That's right, by very, very accurately measuring our distance from three satellites we can "triangulate" our position anywhere on earth. Forget for a moment how our receiver measures this distance an let us consider how distance measurements from three satellites can pinpoint you in space. The Big Idea Geometrically Step One Suppose we measure our distance from a satellite and find it to be 11,000 Km. Knowing that we're 11,000 Km from a particular satellite narrows down all the possible locations we could be in the whole universe to the surface of a sphere that is centered on this satellite and has a radius of 11,000 miles. Step Two Next, say we measure our distance to a second satellite and find out that it's 12,000 miles away. That tells us that we're not only on the first sphere but we're also on a sphere that's 12,000 miles from the second satellite. In other words, we're somewhere on the circle where these two spheres intersect. Step Three If we then make a measurement from a third satellite and find that we're 13,000 miles from that one, that narrows our position down even further, to the two points where the 13,000 mile sphere cuts through the circle that's the intersection of the first two spheres. So by ranging from three satellites we can narrow our position to just two points in space. To decide which one is our true location we could make a fourth measurement. But usually one of the two points is a ridiculous answer (either too far from Earth or moving at an impossible velocity) and can be rejected without a measurement. More about GPS and its usages in the following issue of “Get Tuned”
One-day Workshop on Automobile Electronics On December 8th 2009, the Department of Engineering hosted a one-day workshop on automobile electronics. The seminar which was well attended by several teachers from technical schools was organized by Sprel Ltd™ and was presented by Mr Philip Rutt, Automotive Distribution Manager of Pico Technology, UK. The morning theoretical session was followed by an afternoon practical session at the A’ Technical School in Nicosia.
Satellite-based Positioning Systems - GPS What is GPS? The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. GPS uses these "man-made stars" as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter! In a sense it's like giving every square meter on the planet a unique address. GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. And that makes the technology accessible to virtually everyone.
How GPS works? Here's how GPS works in five logical steps: 1. The basis of GPS is "triangulation" from satellites. 2. To "triangulate," a GPS receiver measures distance using the travel time of radio signals. 3. To measure travel time, GPS needs very accurate timing which it achieves with some tricks. 4. Along with distance, you need to know exactly where the satellites are in space. High orbits and careful monitoring are the secret. 5. Finally you must correct for any delays the signal experiences as it travels through the atmosphere. Based on the information for your location you can build a number of applications (uses). The most important use of GPS is for navigation in which the GPS device provides the user a well-defined route to its destination by utilizing the map information available in the device. Recourses: http://www.trimble.com
Organic Light Emitting Diode (OLED) Technology ‌continued from first page Current and Future Uses of OLEDs Currently, OLEDs are used in smallscreen devices such as cell phones, PDAs, digital cameras and TV sets. Several companies have already built prototype computer monitors and large-screen TVs that use OLED technology. Research and development in the field of OLEDs is proceeding rapidly and may lead to future applications in heads-up displays, automotive dashboards, billboard-type displays, home and office lighting and flexible displays. Because OLEDs refresh faster than LCDs (almost 1,000 times faster) a device with an OLED display could change information almost in real time. Video images could be much more realistic and constantly updated. The newspaper of the future might be an OLED display that refreshes with breaking news and, like a regular newspaper; you could fold it up when you're done reading it and stick it in your backpack or briefcase.
How OLEDs Work OLEDs emit light in a similar manner to LEDs, through a process called electrophosphorescence.
The process is as follows: (a) The battery or power supply of the device containing the OLED applies a voltage across it. (b) An electrical current flows from the cathode to the anode through the organic layers (an electrical current is a flow of electrons).
OLED Advantages The LCD is currently the display of choice in small devices and is also popular in large-screen TVs. Regular LEDs often form the digits on digital clocks and other electronic devices. OLEDs offer many advantages over both LCDs and LEDs: (a) The plastic, organic layers of an OLED are thinner, lighter and more flexible than the crystalline layers in an LED or LCD. (b) Because the light-emitting layers of an OLED are lighter, the substrate of an OLED can be flexible instead of rigid. OLED substrates can be plastic rather than the glass used for LEDs and LCDs.
-The cathode gives electrons to the emissive layer of organic molecules. -The anode removes electrons from the conductive layer of organic molecules (this is the equivalent to giving electron holes to the conductive layer). (c) At the boundary between the emissive and the conductive layers, electrons find electron holes. - When an electron finds an electron hole, the electron fills the hole (it falls into an energy level of the atom that's missing an electron). -When this happens, the electron gives up energy in the form of a photon of light. (d) The OLED emits light. (e) The color of the light depends on the type of organic molecule in the emissive layer. Manufacturers place several types of organic films on the same OLED to make color displays. (f) The intensity or brightness of the light depends on the amount of electrical current applied: the more the current, the brighter the light.
OLED Disadvantages OLED seems to be the perfect technology for all types of displays, but it also has some problems:
(c) OLEDs are brighter than LEDs. Because the organic layers of an OLED are much thinner than the correspo-nding
inorganic
crystal
layers of an LED, the conductive and emissive layers of an OLED can be multi-layered.
Also, LEDs
and LCDs require glass for support, and glass absorbs some light. (d) The OLED displays require less voltage, often between two and ten volts. OLEDs do not require
backlighting
like
LCDs.
LCDs work by selectively blocking areas of the backlight to make the images that you see, while OLEDs generate light themselves. Because OLEDs do not require backlighting, they consume much less power than LCDs (most of the LCD power goes to the backlighting). This is especially important for battery-operated devices such as cell phones.
Further-
more, as there is no backlight needed, thinner displays can be produced.
(a) While red and green OLED films have longer lifetimes (46,000 to 230,000 hours), blue organics
(e) OLEDs are easier to produce
currently have limited lifetimes (up to around 14,000 hours; 5 years at 8 hours of use a day).
and can be made to larger sizes.
(b) Manufacturing processes are expensive right now.
Because OLEDs are essentially
(c) Organic materials can easily be damaged by water intrusion into the displays. Therefore an im-
plastics, they can be made into
proved sealing process is necessary for OLED displays. Also, the development of the technology is restrained by patents held by a small number of companies. For commercial development of OLED technology it is often necessary to acquire a license.
large, thin sheets. It is much more difficult to grow and lay down so many liquid crystals.
Department Seminar “A
tutorial
on
Advanced
Modulation
Techniques for Optical Communications”
Engineering Joke Once upon a time there lived three men: a doctor, a chemist, and an engineer. For some reason all three offended the king and were sentenced to die on the same day. The day of the execution arrived, and the doctor was led up to the guillotine. As he strapped the doctor to the guillotine, the executioner asked: -
Head up or head down? Head up," said the doctor. Blindfold or no blindfold? No blindfold.
So the executioner raised the axe, and z-z-z-ing! Down came the blade, and stopped barely an inch above the doctor's neck. Well, the law stated that if an execution didn't succeed the first time the prisoner had to be released, so the doctor was set free. Then the chemist was led up to the guillotine.
by Dr. I. Roudas The Department of Engineering held a tutorial on advanced modulation techniques for Optical Communications on Thursday, November 12th, 2009. The purpose of the tutorial was to review recent theoretical and experimental advances in coherent Polarization Division Multiplexed Quadrature Phase Shift Keying (PDM-QPSK) optical communications links. When QPSK is combined with PDM, theoretical spectral efficiency four times larger than binary on-off keying (OOK) can be achieved. One of the many applications is that QPSK and PDM can be used to achieve an effective bit rate of 40 Gb/s by using a symbol rate of only 10 Gbaud (signal symbol rate).
-
Head up or head down? Head up. Blindfold or no blindfold? No blindfold.
So the executioner raised his axe, but before he could cut the rope, the engineer yelled out: - WAIT! I see what the problem is!
Department of Engineering UNIVERSITY OF NICOSIA 46 Makedonitissas Avenue P.O. Box 24005 1700 Nicosia CYPRUS (+357) 22841500 phone (+357) 22357481 fax ece@unic.ac.cy www.ece.unic.ac.cy
The event attracted a lot of interest and was well attended.
About the speaker
- Head up or head down?, said the executioner. - Head up. - Blindfold or no blindfold? - No blindfold. So the executioner raised his axe, and z-z-z-ing! Down came the blade, and stopped an inch above the chemist's neck. So the chemist was set free. Finally the engineer was led up to the guillotine.
The above created a worldwide research interest in 10 GBd, coherent PDM-QPSK optical communications systems during the last few years, which culminated in several record experimental results and the development of application-specific integrated circuits (ASICs) for digital signal processing (DSP) in coherent homodyne synchronous receivers operating at this symbol rate.
Such a significant reduction in the signaling rate is beneficial for two reasons: First, it leads to a dramatic reduction in equipment cost, since off-the-shelf, commercially-available, optoelectronic and electronic components with 10 GHz bandwidth can be used instead of their expensive, 40 GHz bandwidth counterparts. Second, the resilience to linear transmission effects is greatly enhanced. A most desirable feature of QPSK modulation at 10 GBd is the possibility to use practical, all-digital, coherent homodyne synchronous receivers. These coherent receivers can achieve record sensitivities and enable unlimited electronic equalization of chromatic dispersion and polarization mode dispersion, in the absence of nonlinearities.
Dr. Ioannis Roudas, received the B.S. degree in Physics and the M.S. degree in Electronics and Radio Engineering from the University of Athens in 1988 and 1990, respectively. He continued his graduate studies in the Ecole Nationale Supérieure des Télécommunications, in Paris, from where he received the M.S. degree in Components and Devices of Optical and Microwave Communications and the Ph.D. degree in Coherent Optical Communication Systems in 1991 and 1995, respectively. From 1995 to 1998, he was with the Optical Networking Research Department, Bell Communications Research (Bellcore), Red Bank, NJ. In addition, he was an Adjunct Professor of the graduate course entitled “Lightwave Systems” at the Electrical Engineering Department, Columbia University, New York, NY, during the fall semesters of 1997 and 1998. From 1999 to 2002, he was with the Photonic Research and Test Center, Corning Incorporated, Somerset, NJ. Since 2003, he is an Associate with the ECE Department at the University of Patras in Greece. His research interests include polarization-mode dispersion compensation, advanced modulation formats, and optical packet switching. He serves as a Reviewer for the IEEE/OSA Journal of Lightwave Technology, the IEEE Photonics Technology Letters, and Optics Communications.