Source: Nature

<>

Understanding Pulse Propagation in Mode-Locked Lasers

Introduction

Mode-locked lasers are important tools in various fields due to their ability to generate ultrashort pulses of light. In this blog post, we will delve into the numerical simulation of pulse propagation in mode-locked lasers, focusing on a simple example of passive mode locking.

Passive Mode Locking Example

In passive mode locking, a laser resonator is used to generate ultrashort pulses. The resonator consists of various components such as a ring, an output coupler (OC), a gain medium (Crystal), and a saturable absorber (SESAM).

The gain function of the crystal has a bandwidth of 5 nm, the SESAM has a modulation depth of 1%, and the output coupler has a transmission of 5%. In this example, we neglect the effects of chromatic dispersion and Kerr nonlinearity for simplicity.

Pulse Propagation Simulation

By numerically simulating the pulse propagation within the resonator, we can observe the evolution of the pulse over time. The initial pulse duration is chosen to be longer than the steady-state value, allowing us to study the dynamics of pulse formation.

After 5000 resonator round trips, the temporal pulse profile shows that the pulse has drifted away from t=0. This drift is caused by the saturable absorber attenuating the leading wing of the pulse more than the trailing wing.

Conclusion

Numerical simulations play a crucial role in understanding the behavior of mode-locked lasers. By studying examples like passive mode locking, researchers can gain insights into the complex dynamics of ultrashort pulse generation.

Source: MDPI
Feel free to comment your thoughts.