Stationary pulse generation due to self-gain modulation in rare-earth-doped fiber lasers
Boris Nyushkov1, Maksim Radchenko1,2, Igor Korel1,2; 1Novosibirsk State Technical University, Novosibirsk, Russia; 2Institute of Laser Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
Abstract
Conventional methods for generating regular trains of short pulses in fiber lasers are typically based on either the active modulation of laser parameters or the mechanism of saturable absorption. The incorporation of modulators or saturable absorbers into lasers generally complicates the system design, reduce reliability and energy efficiency. We explore, both theoretically and experimentally, new pulse generation mechanism that does not require any saturable absorbers, intracavity modulators or modulated/pulsed pump sources. The method relies upon the self-gain modulation which is achieved by applying the negative optical feedback to a conventional configuration of rare-earth-doped fiber lasers. We demonstrate that the self-sustaining cross-gain modulation in the proposed laser configuration facilitates stationary generation of pulse bunches or single pulses, depending on parameters of the negative optical feedback. By inducing the self-gain modulation in an experimental Er-fiber laser and adjusting the delay in the negative optical feedback, we achieved stationary generation of regular nanosecond-scale pulse bunches with a repetition rate of 30 – 120 kHz (tunable by pump power control). Generation of a regular train of sub-nanosecond pulses with the fundamental pulse repetition rate of 20 MHz is also shown to be achievable with a certain delay in the negative optical feedback. The proposed method is rather general: it was approved also for Yb-fiber lasers. We anticipate that it can facilitate more affordable and reliable pulse generation in a variety of applied laser systems.
Speaker
Boris Nyushkov
Novosibirsk State Technical University, Novosibirsk, Russia
Russia
Discussion
Ask question
