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In this article, we are going to discuss how to transfer audio through laser light. This is a fun little project and the concept is similar to what we see in fiber optics cable, we will use a laser light to send data from one point to another. To be particular, in this project here we are going to transfer our voice from one point to another by shining a laser light on a solar panel. This is made possible by Light Fidelity or (Li-Fi) in short, for those who are new Li-Fi is a technology in which data can be transferred using light, in our case we sending our voice as data and using Laser as light source.

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The highlight of this project is its simplicity, you can easily build this over a weekend with commonly available components. If you are interested in Li-Fi you can also check our our Li-Fi Text communication and Li-Fi audio transfer projects.

So, without further delay, let’s dive into building the project.

How to transfer Audio using Laser Light?

Transmitting Audio via Laser light is simple than it sounds. On the transmitter side we have a microphone which converts our voice into electrical signals, this signal then amplified using an audio amplifier and the output of this amplifier is directly connected to a LASER diode. This light is then pointed towards the solar panel on our received circuit. Agian, on the receiver side the solar panel is connected as audio input for another audio amplifier which amplifies these signals and plays it on a speaker. All of this works because of the ability of light to carry data.

Transmitter Side

Audio to Electrical Signal:

Our aim is to transfer the live audio signal, so in that case, we need some sort of microphone to convert the audio signal to an electrical signal. Actually, speaking, there comes a little bit of a complex circuit to achieve a perfect output. So, to make it simple, we are going to use the MAX4466 Microphone Amplifier Module, you can check out the link if you want to know more about this microphone module.

Above, you can see the GIF video representing the working of the MAX4466 Microphone Amplifier Module. Now we have the electrical signal that needs to be transmitted over the laser.

Electric Signal to Laser Beam:

In the above process, we have received the electrical signal. Now this electrical signal is used to drive the laser light beam. It can be done using multiple ways, like using some analog circuits (i.e., switching MOSFET). But to make it simple and more effective, we are using a Mini 5V Audio Amplifier Module based on PAM8403, as you can see in the image below.

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The reason behind choosing this is simple. It works in the 5V range, so it can be easily integrated with the MAX4466 Microphone Amplifier Module. It also has an inbuilt potentiometer to adjust the amplitude of the output, and more importantly, it is more affordable. You can use whatever amplifier board you have or even create your own circuits to do the job right. Still, I suggest using the audio amplifier board for better output and hassle-free work. We have previously used the PAM8403 to also build a simple DIY Bluetooth speaker, you can check that out if you are intrested.

Now, a laser diode can be connected to the output of the PAM8403 module.

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Above, you can see the laser diode we are using. If you would like to reduce the current fed to the laser, you can use a resistor of minimum value. Here, the laser we are using has a built-in 30-ohm resistor in series with the power input. If you feel like reducing the power, you can do so by adding an extra resistor in series or even adjusting the potentiometer in the PAM8403 module.

Receiver Side

Laser Light to Electrical Signal:

As in the last step we have already completed the transmitter side, here we go with the receiver side. So the primary process is to convert the audio signal from the laser light beam to its original state of electrical signal. Here, generally, we can use any light-based sensor (i.e., LDR, photodiode, etc.) to do the job right, but those with smaller reception areas are quite tough to use. However, they are not unusable; you can even use them. But here in this project, I am going to use a larger array of photodiodes, which is also known as the solar panel.

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I am going to use a small toy solar panel. Despite its minimal power output, it is more than enough for our project. So, by using this solar panel, we are going to convert the laser beam to an electrical signal.

Electrical Signal to Speaker:

The electrical signal from the solar panel cannot be directly fed to the speaker due to its low power output. Even with a larger solar panel, the small point of light hitting the panel doesn’t make a significant change in the output; we will only get a higher DC voltage with a larger panel. However, we need an analog voltage.

To solve this issue, I am going to use the same amplifier module that we used on the transmitter side so that the output electrical signal can be effectively amplified and passed to the speaker.

Regarding the speaker, you can use any speaker compatible with your amplifier module. I am using a 4-ohm, 10-watt speaker, as shown in the image above.

Therefore, we have successfully completed the theory part. I hope you all understand the main concept behind choosing the components and the workings of the project. So, let’s move on to the hardware part of the project.