Experimental Study of Modulation Dynamics of Laser and Photodetector to Realize Visible Light Communication .
Wireless communication providing ubiquitous and higher bandwidth services for access networks and data centers is under extensive research since the end of last decade. Since, Radio Frequency (RF) communication suffers from interference, high latency issues and penetration through the walls causing
2025-06-28 16:27:09 - Adil Khan
Experimental Study of Modulation Dynamics of Laser and Photodetector to Realize Visible Light Communication .
Project Area of Specialization Electrical/Electronic EngineeringProject SummaryWireless communication providing ubiquitous and higher bandwidth services for access networks and data centers is under extensive research since the end of last decade. Since, Radio Frequency (RF) communication suffers from interference, high latency issues and penetration through the walls causing security issues. It also suffers from power inefficiency as it requires separate setup for communication of RF waves. Therefore, to overcome these limitations, Visible Light Communication (VLC) is an alternative solution due to its inherent higher bandwidth, free of charge optical band spectrum and immune to Electromagnetic Interference (EMI). In addition, VLC can be used for illumination and it consumes less power. Great progress is reported for high-speed data transmission using Light Emitting Didoes (LEDs) as a visible light transmitter. In this project a communication system will be designed that will use low-cost laser and photodiode. The detailed characterization of laser and photodiode will be carried out by investigating their modulation dynamics and bandwidths. This characterization will provide the bandwidths capabilities of both the laser and photodiode that will enable us to analyze the performance of the designed communication system.
Project ObjectivesWe demonstrate high-speed data transmission with a commercial high power laser diode at 450 nm. Bandwidth will be achieved at some current using a high-speed visible light communication setup.Free-space data transmission rate was achieved at room temperature.
Project Implementation MethodThe intended work will start with the theoretical investigation followed by modelling and simulation work. Simulated results will be finally verified through experimental work. VLC will be used to measure the performance of a laser (450nm). As a first step, to find the laser characteristics, the Light – Current (L-I) curve will be plotted that will characterizes the emission properties of a semiconductor laser as it will show the current that needs to be applied to obtain a certain amount of power. In addition, the characterization of photodiode will be done. Then, a sinusoidal signal generated by an RF signal generator will be directly modulated as shown in the figure below using a bias tee. The signal of this laser diode will be transmitted to a high-speed silicon photodiode. The light output from laser diode is then collected into electrical signal using the photo detector. The received signal is measured by an analyzer at different currents. To determine the high data rate characteristics of the laser diode, a pseudo-random bit sequence (PRBS) from a pattern generator will be added at each DC operating bias and eye diagram will be plotted.
Benefits of the Project?It supports larger bandwidth and hence overcome bandwidth limitation of RF communication.
?VLC communication works when both source and receiver are in LOS within the same room. VLC based data communication can not be intercepted by any one from the another room. Hence VLC provides secured communication unlike RF communication.
?VLC source is used for both illumination and communication, it has low power consumption. Hence VLC is power efficient system.
?VLC is light based communication. Hence it is not affected due to EM radiations from RF systems.
?It is easy to install.
The intended work includes modelling and simulation work. Simulated results will be finally verified through experimental work. VLC will be used to measure the performance of a laser. As a first step,the Light – Current (L-I) curve will be plotted that will characterizes the emission properties of a semiconductor laser as it will show the current that needs to be applied to obtain a certain amount of power. In addition, the characterization of photodiode will be done. Then, a sinusoidal signal generated by an RF signal generator will be directly modulated. The signal of this laser diode will be transmitted to a high-speed silicon photodiode. The light output from laser diode is then collected into electrical signal using the photo detector. The received signal is measured by an analyzer at different currents. To determine the high data rate characteristics of the laser diode, a pseudo-random bit sequence (PRBS) from a pattern generator will be added at each DC operating bias and eye diagram will be plotted.
Final Deliverable of the Project Hardware SystemCore Industry TelecommunicationOther IndustriesCore Technology Big DataOther TechnologiesSustainable Development Goals Industry, Innovation and InfrastructureRequired Resources| Item Name | Type | No. of Units | Per Unit Cost (in Rs) | Total (in Rs) |
|---|---|---|---|---|
| Total in (Rs) | 77200 | |||
| Laser diode | Equipment | 1 | 8200 | 8200 |
| Single mode fibre 5 km | Equipment | 1 | 11000 | 11000 |
| Variable optical attenuator | Equipment | 1 | 5500 | 5500 |
| Power supply (12 V 5 A Dc) | Equipment | 1 | 8000 | 8000 |
| Arduino Uno | Equipment | 2 | 2200 | 4400 |
| Arduino Mega | Equipment | 2 | 3400 | 6800 |
| Optical circulator | Equipment | 1 | 18000 | 18000 |
| Dc battery | Equipment | 6 | 300 | 1800 |
| Wire cutters | Equipment | 1 | 1800 | 1800 |
| Connectors | Equipment | 5 | 200 | 1000 |
| Wires | Equipment | 5 | 200 | 1000 |
| ESP adopter | Equipment | 1 | 1700 | 1700 |
| Poster printing | Miscellaneous | 10 | 250 | 2500 |
| Boucher printing | Miscellaneous | 50 | 100 | 5000 |
| Stationery | Miscellaneous | 5 | 100 | 500 |