On the Q-switched operation of Titanium:Sapphire lasers using a graphene-based saturable absorber mirror

Abstract

We numerically demonstrate Q-switched operation of Titanium:Sapphire lasers using mono and multilayer graphene, deposited on a totally reflecting end mirror as a saturable absorber. Output energies, pulse duration and repetition frequencies of the Q-switched pulse trains are given as a function of the pump intensity for different number of graphene layers and cavity lengths. For the geometries studied, pulses from 16.2 to 467 ns can be achieved, with energies ranging from 8.7 to 71 µJ and repetition rates from 0.057 to 2.27 MHz. These results can be useful for designing and building laser cavities for Q-switched and mode-locked operation in laser media with short lifetimes as Titanium:Sapphire.

Q-Switched Operation with Carbon-Based Saturable Absorbers in a Nd:YLF Laser

“…In previous works, a model given by Haus and Spühler [20,21] has given good results when comparing experimental with simulated Q-switched operation using a monolayer G-SAM (graphene saturable absorber mirror) in a Nd:YLF laser [10] or predicting Q-switched operation in a short-cavity titanium:sapphire laser [19]. In this model, the intracavity power P , the gain g and the density of population inversion q can be calculated with the following set of equations [20,21]:…”

“…Short-length cavities give shorter pulse durations, higher output powers and higher repetition rates in the Q-Switched regime [10,19] than longer ones. The SAM was considered to have a reflectivity R SAM = 0.998 without the saturable absorber on it and the output mirror R OM = 0.98.…”

“…Hence, when looking for mode locking operation in a laser using a saturable absorber to produce ultrashort laser pulses, some attention should be paid to the possibility of Q-switched operation, which can make it more difficult to find pure mode locking. For example, the titanium:sapphire laser, which has optimal performance in mode locking, can be affected by the appearance of Q-switch in certain cavity designs [17][18][19]. In this paper, we want to evaluate the convenience of using carbon nanotubes or graphene in diode-pumped lasers, evaluating their performance as saturable absorbers for Q-switched operation.…”

Passively Q-switched Er,Yb:GdAl3(BO3)4 laser with single-walled carbon nanotube based saturable absorber

“…The set of equations ( 1)-( 6) was solved numerically. A similar approach was used in [15] where a separate equation for the losses introduced by a graphene-based saturable absorber mirror for a Ti 3+ :sapphire laser was used.…”