Laser light sources have some key differences compared to LEDs. Let’s break it down carefully.
- Like LEDs, lasers can be modulated directly with an electrical signal to vary the intensity.
- You can use a baseband signal (after adding a DC bias if needed) or a high-frequency carrier for advanced modulation.
- Laser diodes typically have much higher bandwidth than LEDs (hundreds of MHz to tens of GHz), so they can support higher data rates and faster modulation.
Key Differences Between LED and Laser Sources
| Feature | LED | Laser |
|---|---|---|
| Beam Pattern | Lambertian (diffuse) | Highly directional (narrow beam) |
| Bandwidth | Low (~10s of MHz) | High (~100s of MHz – GHz) |
| Intensity Modulation | Easy, safe | Needs careful biasing to avoid damage |
| Coherence | Incoherent | Coherent (phase-stable light) |
| FOV at Receiver | Wide (less alignment critical) | Very narrow (alignment critical) |
Summary
- Benefits of Laser:
- Higher bandwidth → faster data rates possible
- Narrow beam → requires precise alignment
- Coherence → can support advanced optical modulation techniques