Hysteresis in an erbium doped ZBLAN waveguide GHz mode-locked laser

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Passively mode-locked fiber lasers are crucial for generating ultrashort optical pulses.
• Hysteresis phenomena in lasers can lead to complex dynamics and limit tunability.
• Erbium-doped ZBLAN chip waveguide lasers offer potential for compact and versatile laser systems.

Purpose of the Study:

• To experimentally observe and numerically analyze a new type of hysteresis behavior in a passively mode-locked erbium-doped ZBLAN chip waveguide laser.
• To investigate the influence of spectral tuning and intracavity dispersion on laser pulse characteristics.
• To understand the underlying physical mechanisms responsible for the observed hysteresis.

Main Methods:

• Experimental setup involving a passively mode-locked erbium-doped ZBLAN chip waveguide laser.
• Tuning the spectral transmission window by translating a collimation lens.
• Varying the net intracavity dispersion.
• Numerical modeling to simulate laser dynamics and hysteresis.
• Analysis of pulse width, spectral bandwidth, and bistable pulse characteristics.

Main Results:

• Observation of a novel hysteresis behavior in pulse width and spectral bandwidth.
• Demonstration of bistable pulse characteristics and abrupt spectral transitions.
• Hysteresis is persistent in the single-pulse operation regime.
• The phenomenon is strongly dependent on the sign and magnitude of intracavity dispersion.
• Numerical model successfully confirms the experimental hysteresis.

Conclusions:

• The observed hysteresis arises from the interplay between dispersion-induced chirp and delayed absorption recovery of the saturable absorber mirror (SESAM).
• This finding provides new insights into the complex dynamics of mode-locked lasers.
• The results are significant for understanding and controlling laser behavior in optical systems.