Transform-Limited Optical Pulse Generation up to 20-GHz Repetition Rate by a Sinusoidally Driven InGaAsP Electroabsorption Modulator

We propose and demonstrate a simple technique to generate a transform-limited optical short pulse with variable repetition rates by using a sinusoidally driven InGaAsP electroabsorption modulator without any optical resonators. By using the pulse compression effect due to nonlinear attenuation characteristics to the applied voltage to the modulator, a transform-limited optical pulse can be generated just with sinusoidal modulation. Theoretical calculation and experimental results show that the pulse shape is very close to sech2 shapes, and the pulse width can be easily varied by the bias and modulation voltages. Transform-limited optical pulse generation with a minimum pulse width of 11 ps was successfully achieved by the sinusoidally driven modulator up to 20-GHz repetition rate. The time-bandwidth product was as small as 0.32.