Fiber Optic Receiver

About the fiber optic receiver

The device used to convert the signal back from light to electrical form is usually either a PIN diode or a phototransistor. Phototransistors have good sensitivity but only a low bandwidth. On the other hand, PIN diodes have a much higher bandwidth but a lower sensitivity. If both high bandwidth and high sensitivity are required, then special avalanche photodiodes are used, but at a severe cost penalty. The same considerations about losses at the interface between the cable and receiver apply as for the transmitter, and both polishing and cleaving are used to prepare the fiber ends.

The output voltages from the receiver are very small and amplification is always necessary. The system is very prone to noise corruption at this point. However, the development of receivers which incorporate an amplifier are finding great success in reducing the scale of this noise problem.

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