Intracavity laser diode pumped and modulated Er3+-doped fiber lasers

We reported on a pulsed compound Er³⁺-doped laser that simultaneously uses an intracavity laser diode for optical pumping, gain or phase modulation, and as a bandwidth control etalon. We demonstrate a simple method to produce high-energy pulses with peak powers up to 100 times the average power, and with durations on the order of 1 μs using the synchronization of relaxation oscillations by drive current modulation of the intracavity pump laser diode. The forced sustained relaxation oscillations are shown to depend on wavelength, and the frequency locking curve exhibits strong asymmetry with hysteresis behavior. Tunable locked spiking operation provides an interesting tool for characterization of the laser dynamics. We have found that the relaxation oscillations and laser transition behavior of the Er³⁺ -doped fiber laser are somewhat different in 1.53 and 1.55 μm bands. The substantial finding is that the fiber laser, operating at λ=1.53 μm, could be mode locked by modulation of drive current of 0.98 μm pump laser diode. FM mode locking was obtained with an output pulse width of ≈400 ps, which was limited by bandwidth of laser diode etalon