Transform-limited optical pulse generation up to 20-GHz repetition rate by a sinusoidally driven InGaAsP electroabsorption modulator

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