The role of the optical transmitter is to:
- convert the electrical signal into optical form, and
- launch the resulting optical signal into the optical fiber.
The optical transmitter consists of the following components:
- optical source
- electrical pulse generator
- optical modulator (see Figure 1).
The launched power is an important design parameter, as indicates how much fiber loss can be tolerated. It is often expressed in units of dBm with 1 mW as the reference level (see Figure 2).
Figure 1: Transmitter components
Figure 2: Laser Power Units