Study of Gain Switching in Vertical Cavity Surface Emitting Laser under Different Electrical Pulse Inputs

Vertical cavity surface emitting laser (VCSEL) is a strong candidate for short pulse generation among the other semiconductor lasers in the era of laser technology. A 1550 nm, low power VCSEL is excited under different current shapes and the chief laser parameters are found out. The concept of gain switching under various current profiles are utilised effectively to bring out maximum laser power with minimum pulse width, which are the essential factors for long haul high speed optical data transmission. For a haversine electrical current input with 3.7 Ith amplitude, a laser peak power of 2.2 mW at 57 ps pulse width is obtained. In the case of trapezoidal pulse, 67 ps pulse width is obtained for 2.6 Ith current amplitude. It is also observed that square pulse of amplitude 2 Ith produces short optical pulse of 0.887 mW peak power and 89 ps width which shows the best performance when compared to other forms of pulses discussed in this work at the same input condition.