Laser Communication

Project Description

Have you ever wondered how we are able to send information across long distances to satellites or over oceans to other continents Laser communication systems encode information in the laser light by modulating its intensity. When the light hits the receiver, the changes in intensity are converted into an electrical signal and the information is recovered. The principle is used in Bluetooth, the internet, and cellphone communication.

In this activity, students will use the audio output from a cell phone, and transmit the signal via laser light to a solar cell receiver.

Project Notes

Transmission Module

Converts digital electrical signal to laser light through amplitude modulation:

Accomplish amplitude modulation through a transformer:

Receiver Module

Converts signal from laser light to digital electrical signal using a solar cell:

Anatomy of an Aux Cord

Wiring Techniques

Jumper Wires

Twist-on Wire Connectors

Laser Safety Considerations

  • Do not stare into the laser beam.
  • Do not point the laser at others.
  • Carefully handle and be aware of where you are pointing the laser.
  • Turn the laser off (by taking the batteries out) when you’re not using it.

Supply List

Transmitter

Audio cable, 3.5mm, cut end: DigiKey P/N CA-2207

Audio transformer: Amazon, CynKen P/N EI14

Laser diode: Amazon, GeeBat P/N 80-141-10

Battery pack, AA, 3 cells: DigiKey P/N BH3AA-W

Jumper wires, female to female: Amazon SUNKEE 100pcs

Receiver

Solar cell: Amazon 5V, 160mA 80x80mm

PVC pipe: McMASTER-CARR, P/N 4880K74

Audio cable, 3.5mm, cut end: DigiKey P/N CA-2207

Twist-on wire connectors, No. 22-14 gauge: Amazon 1,000pcs

Amplified speaker, example: RadioShack P/N 2771008

Circuit Diagram