A Ho3+-doped photonic crystal fiber laser with output wavelength of 2077nm has been demonstrated using a 1992nm Tm3+-doped fiber laser with output wavelength of 1992nm as a pump source. And the optical- optical conversion slope efficiency is 41.3%. In order to optimize the output power of the Ho3+-doped photonic crystal fiber laser, a simple quasi-three level system theoretical modeling is developed in the condition of Stark-splitted energy level diagram of holmium ion. We obtain the theoretical optical- optical conversion slope efficiency 43.5%, which is higher than the experimental 41.3%. Furthermore, the relative deviation of the η is 5%, which shows the theoretical data is good agreement with experimental data. According to the modeling, the influence factors of the output power have been theoretically studied, in detail. The results show that there are an optimal range of Ho3+-doped concentration n0, transmittance of coupled output mirror T2 and length of the PCF L, respectively. Furthermore, the output power is approximately equal to maximum in the range of the optimal value.
In this paper, we present a theoretical model to describe the passively-Q output characteristics of quasi-three level Ho3+-doped Fluorotellurite fiber lasers. According to the model, we have studied the factors impacting on the output characteristics of the laser through numerical simulation method. The calculating program of the theoretical model is written using the Matlab language. We obtain the passively-Q output laser with the pulse repetition rate of 13.1 kHz, pulse width of 28.63ns, peak power of 25W, and pulse energy of 0.34 μJ at the pump power of 0.1W. When the pump power increases, the pulse width of the laser decreases, the pulse repetition rate linearly increases, both the pulse energy and the peak power also increases. The pulse width of the laser linearly increases and the pulse energy increases when the length L does. When the output coupler transmission T increases, both the pulse width and the peak power of the laser decrease. The pulse energy of the laser firstly increases and then decreases when the output coupler transmission T does. We qualitatively analyze what causes the change laws of the outputlaser characteristics, such as the pulse width and the pulse energy.