Photonic Links Lab - 1 - Optical Voice Link Courtlan Hall & Melanie Jasper Cosmos UC Davis, Cluster 2 Fundamental Science and Technological Applications Niels Gronbech Jensen and Diego Yankelevich July 30, 2007 Photonic Links Lab - 2 Abstract Sound waves can be transformed into optical waves that travel much faster. Sound waves travel at a speed on 344 meters per second and optical waves travel at 3.0 x 10^8 meter per second. We measured the optical bandwidth, because if the frequencies of the sound waves are too high then the optical fibers will not transmit the information. The amplitude of the graph decreased as the frequency increased. We also measured the difference in phases between to sinusoidal graphs by multiplying the frequency by the change in time by two pi. We noticed that the radians grew as the frequency of the wave was increased. Introduction A fiber optic cable if created from a mixture of glass and plastic. These cables are capable of transmitting light across large distances at very fast speeds. The cables have a core, which is the glass, the cladding surrounding the core. The cladding creates a better refractive index making it easier for the light to travels through without propagating much. Then the cladding is covered by Kevlar fibers to provide strength to the cable. And finally the cable is wrapped in rubber to keep away dirt, water and anything else that might interfere. Photonic Links Lab - 3 Figure 1 A Fiber Optic Cable Fiber optic cables carry data all around the world. Optical waves have the ability to carry data, depending on the frequency and amplitude. Optical fibers have a certain bandwidth that the must operate in. if the frequency is too high for the bandwidth, then the amplitude will be so small that it would be almost impossible to receive any data through the waves. Sound waves travel at a much slower rate than optical waves. The two waves are very different. Sound waves are similar to a ripple in a pond, they expand and diverge making it difficult to carry information on them. However, optical waves are sinusoidal. They travel extremely fast, at around 3.0 x 10^8 meters per second in a vacuum. Optical fibers have revolutionized communication. It is now much faster and easier to send and receive messages across long distances. Sound waves in America can now be transformed into optical waves, and then be sent through optical fibers to Europe. In Europe they are transformed back into sound waves and the information is received in a fraction of the time it would take for radio waves to transmit the information. Photonic Links Lab - 4 - Figure 2 The web of fiber optic cables across the oceans In this lab we created a fiber optic link that was capable of transferring sound waves through fiber optic cables by transforming them into light waves, and by using an oscilloscope we measured the light bandwidth and phase difference between two sinusoidal. Materials Wire cutters Small Phillips screwdriver 1ml water 25-watt soldering iron two 9V batteries Razor blade Needle-nose pliers Wrench Rosin-core solder 18-gauge wire-stripper Dual-trace oscilloscope Transmitter BNC (T) connector Alligator clamps Receiver Fiber optic cable Photonic Links Lab - 5 - Methods To begin the lab we built a transmitter and receiver from an optical voice link kit. We followed the kit instruction booklet for assembly. We soldered all the parts to the chip and inserted 9-volt batteries for the power source. Then we connected the transmitter to the receiver with a fiber optic cable and tested the link by speaking into the microphone on the transmitter and listening for our voice come out of the speaker on the receiver. Then we attached alligator clams to the speaker and attached it to the oscilloscope and signal generator to find the sinusoidal graph. We measured the bandwidth of the optical voice link kit by measuring at what frequency the amplitude became too small to read. We also measured the difference in radians between two sinusoidal graphs at different frequencies. Photonic Links Lab - 6 Frequency Hz Amplitude mV 100 300 1000 3000 5000 10000 30000 50000 100000 300000 500000 815 810 800 750 500 375 100 75 45 15 5 Amplitude (mV) Amplitude of a wave as a function of frequency 1000 800 600 400 200 0 Series1 1 100 10000 Frequency 100000 0 Photonic Links Lab - 7 - Frequency Hz 100 1000 5000 10000 50000 100000 Radians 1.319 6.283 12.566 4.712 14.1368 62.83 Frequency vs Radians 70 60 R a d ia n s 50 40 30 20 10 0 1 10 100 1000 Frequency (Hz) 10000 100000 Photonic Links Lab - 8 - Analysis In the first experiment we discovered that the photonic link worked well. Though it also had to be very exact. If two pieces of wire were just barely touching then it would not work. We also had to tune it with a knob attached to the transmitter. In the end our photonic link worked well. Once we got it working we tried to test the frequency that the link worked with. We steadily raised the frequency until we were unable to read it. We discovered that the link worked at a wide range of frequencies. We were able to read it all the way until 500,000 Hz. For the last experiment we measured the difference of radians between two sinusoidal graphs. We discovered that the difference becomes more drastic between 10,000 and 100,000 Hz. Conclusion We discovered that an even our simple optical links worked at a wide variety of frequencies. It used the laser running through the optical cable to transmit information. The optical link worked well and has good potential to become more commonly used in the future. It has advantages over regular electric cables because it is unaffected by the weather. The optical links work well to transmit information.