Different Kinds Of Optical Swi Essay, Research Paper

Different Kinds of Optical Switches:

The biggest problem with creating an all-optical network would be the switching; re-routing the information from source A to destination B . When information is sent, it does not flow directly from point A to point B. It passes through a series of switches that narrow the path down, and eventually the signal reaches point B. These switches have thousand s of possible routes which information can be transfered. Right now, the optical networks that stretch across the globe switches electronically. This is a huge set back, if you are trying to make a network that works at the speed of light. Light travels at about 982,080,000 feet per second, and electrons at 300,000 ft/sec. So when an optical network uses an electronic switch, the light first has to be converted to an electronic signal, then it has to go through the switch, and finally the electrons are converted back to a light beam. This process only takes a few milliseconds, but these seconds can be compared to what an optical switch operates at which is nanoseconds. The signal is slowed down so much that it can be compared to going down the highway at top speed, then when you reach the off ramp you stop, get out of your car, stumble and walk awkwardly, and slowly to the next onramp then you get back in a car and speed off at top speed. Optical to electronic switches are more of an extreme, the light is going over 3,000 times faster than the electrons. It is a very unnecessary and costly reduction in speed.

Many corporations have took interest in this problem and decided to take action by inventing optical prototype switches. Some of which are faster then others, but are all faster than optical-electric switches. One of the best working switches is the MEMS Switch (shown on diagram). It uses mirrors that are less than half a millimeter in diameter. These mirrors reflect the light from one pipe to another. There are 256 mirrors that fit onto one piece of silicon that is 2.5 cm squared. There is room to improve in the number of mirrors in MEMS. But in order to make the switch efficient there will need to be over 1000 mirrors. In operation the light beam runs through an input pipe, bounces off of a MEMS mirror then diflects off of the reflector, which sends it to a mirror that reflects the light a third time into an outgoing pipe. This process takes a few milliseconds, and is thousands of times faster than any optical electric switch; it also uses hundreds of times less energy. The one problem with a mirror switch is that the mirrors may get misaligned, and send data off in strange directions. Another type of switch is the bubble switch. It uses a very unique method of reflecting a beam of light using an inkjet bubble. What happens is the light is sent into an x shaped intersection. At the center of the x there is an inkjet head, if the switch is told to turn on, the inkjet head will blow a microscopic bubble, which reflects the light down a different pathway. The inkjet head produces a bubble in a strategic point to make the ray of light make a right turn, at a right angle. This method is also very small in size, but there are problems trying to build switches that have 1000 input pipes and 1000 output pipes, due to the number of printer heads it uses. A third type of switch uses liquid crystals to direct light in different directions. It can change the orientation of polarized light, either vertical or horizontal, depending on whether a voltage is applied. The light then passes through a beam displacer, where, if the light is polarized horizontally, goes straight through. If it is polarized vertically, it moves to the right. There are many problems with this kind of switch. For one, the liquid crystals take a relatively long time to switch the polarization of the light. It also can distort the light a bit when it passes through the liquid crystals.

These are definitely not the only switches being developed for fiber optics. There is a switch that is being developed that heats the wavelength which changes the rate of the pulse of the light, and that determines which outgoing pipe to put the light into. So there are definitely some creative minds going into the development of this technology. There is also a lot of money going into it, funds are being sent to developers from many phone and television companies. They are all hoping to get a part of the wire that can carry multiple transmissions of different devices (i.e. internet, TV, phone). Fiber optics, the ultimate in transferring data.