Fiber Optic Transmission Project

In this project, we constructed a fiber optic transmission system based on a solid-state semiconductor Class IIIb laser kept at a maximum of 5 mW (which is barely eye-safe assuming normal or faster than normal blink reflex).

Although any kind of data can be sent through a fiber optic cable (such as audio, video, and packet-based information like that of TCP/IP, UDP, and other internet-based transmission schemes), we chose to send audio signals by modulating the drive current of a laser with the audio output of a standard CD player.

We then propagated this signal through two different mediums: an air gap of about 10 centimeters and 3 meters of single-mode fiber optic cable. We received the signal using a photodetector coupled with an amplifier, and demodulated the signal using a linear correspondence between audio voltage input, laser intensity, and voltage output.

Finally, we plugged a a signal spectrum analyzer, as well as a standard pair of computer speakers, into our amplifier to see if there was any appreciable loss in sound quality. There was significant loss in the 0 - 60 Hz range as well as the 17-26 kHz range, but almost flawless performance in between.

To put that in perspective, our system can accurately transmit about 96% of the commonly accepted range of human hearing (20 Hz - 18 kHz), and 100% of the normal range of the human voice (300 Hz - 3 kHz).

Category:

People & Blogs

[AnggusKopeliani]

профаны...)

[BabyGracious]

You're not using a digital signal via the laser? So rather than on/off you're modulating beam intensity to represent frequency?

[Films4You]

Save research funding 'Google Digital Optical Cables'

Fiber optic technology sends data without electricity through a conductor. Instead of electrical signals, modulated light is used to quickly transmit data through an insulated glass Fiber-type material.The signal cannot be disrupted by outside sources, especially electricity which in the form of your AV power cords can cause interference in your standard copper based cable.

[TravvyG]

This stuff interest me haha hey people I wonna study IT in the network department like making and learning about All sorts of Networks and how to maintain and manage them etc at Uni but I don't know what the Subject is called can anyone tell me please thanks in advance. Btw I'm in Australia so anyone know any Universitys in Queensland that have high quality education in that area thanks again ^_^

[BashPants]

this is noob stuff. I did this back in high school... we also used about 12 mirrors. The pros can transfer super fast internet connection using this same technology. in the big tech shows that need alot of pipe they beam lasers from the rooftops.

[NiGhtMarEs0nWax]

its not really that hard, although the principles are easy to understand, it would take a certain level of understanding from electronics and programming pov. im asuming the guy with the beard is the programmer and the guy with the silly haircut is the electronics nerd :)

good work though guys, im totally jelous

[bilzoo2000]

oops, i may have errored when i assumed MIT had The only EECS program...

[bilzoo2000]

Damn MIT students with their hard to understand explanation about fiber optic transmission. Actually, I like the video, maybe I'll make something like this if i can find some fiber optic cable.

[taichikamiya]

I like the work u both did :) so 5stars for this video. Now i see i can be doing cool stuff after univerity basic studies :D