Question

This problem concerns external modulation of a laser source. The transfer characteristic of the electro-optic intensity modulator shown in Fig. 2 is given by

Know the bias voltage Vb is changed from 2 Volt to 1 Volt. Assume that the fibre loss is 0.3 dB/km.

(i) Sketch the transfer characteristic of the electro-optic modulator and show the new bias point. By considering this characteristic, state whether you expect the small signal gain to be higher or lower for this new bias voltage of Vb = 1 Volt compared to the value for Vb = 2 Volt.

(ii) Which of the above bias voltages do you recommend for design?

38 (mw) out- 4 RF Bias IP Laser *-30 km Optical Detector Electro-optic Modulator Fig. 2

Answer 1

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