A Maleki

Analytical model for temperature, stress and strain distribution inside a side-pumped Nd:YAG laser rod having a Gaussian pump profile

In this paper, we introduce an analytical model for the temperature distribution of a diode side-pumped Nd:YAG laser rod by considering a Gaussian pump profile, taking into account the dependence of thermal conductivity on temperature. The stress and strain components are then derived by considering the dependence of the thermal expansion coefficient on the temperature. Our analytical model shows a very good agreement with numerical results. The maximum relative error, when compared with numerical results, is about 0.2 and 2.0% at the center of a laser rod for temperature and stress respectively.

A compact diode-pumped pulsed Nd:YAG slab laser based on a master oscillator power amplifier configuration

In this paper, the design and construction of a pulsed Nd:YAG laser is described. The structure of this laser is based on a master oscillator power amplifier system. A master oscillator is an electro-optical Q-switched Nd:YAG rod laser. Face-pumping is used for the excitation of the slab structure, and a double-pass method is designed for the amplification stages. Two Nd:YAG zigzag slabs are utilized as power amplification stages in this laser. The laser diodes are stacked in a compact configuration and are used for rod and slabs pumping. The total pump energy in the amplifier stages is 3200 mJ at 808 nm. The output pulse energy achieved at 1064 nm is about 850 mJ of 10 ns pulse duration corresponding to 26.5% optical-to-optical conversion efficiency. Moreover, this laser can generate pulse energies around 430 mJ at 532 nm. The dependence of the output energy of MOPA and second harmonic generation operations on different pulse repetition rates (PRRs) from 1 to 100 Hz has been investigated. Experimental results show that the maximum fluctuations of the output energies are about 2.5 and 4% for 1064 and 532 nm, respectively.

Analytical model for temperature distribution of an end diode-pumped laser slab with Robin boundary conditions by Green’s function method

In this paper, an analytical model is introduced for temperature distribution of an end diode-pumped laser slab by Greens function method. To solve the heat equation, Robin boundary conditions are considered because four lateral faces of the slab are cooled by water. An analytical model is extracted for single and dual end-pumping configuration. For an example, the 2D and 3D temperature distributions are plotted and our analytical model is validated by numerical solution based on the finite element method (FEM). The results show that our model has very good agreement with numerical solution. Furthermore, dependence of the temperature distribution on absorbed pump power is shown.

Experimental study of electro-optical Q-switched pulsed Nd:YAG laser

We report the specification of a compact and stable side diode-pumped Q-switched pulsed Nd:YAG laser. We experimentally study and compare the performance of the pulsed Nd:YAG laser in the free-running and Q-switched modes at different pulse repetition rates from 1 Hz to 100 Hz. The laser output energy is stabilized by using a special configuration of the optical resonator. In this laser, an unsymmetrical concave–concave resonator is used and this structure helps the mode volume to be nearly fixed when the pulse repetition rate is increased. According to the experimental results in the Q-switched operation, the laser output energy is nearly constant around 70 m J with an FWHM pulse width of 7 ns at100 Hz. The optical-to-optical conversion efficiency in the Q-switched regime is 17.5%.

Analytical model for thermal lensing and spherical aberration in diode side-pumped Nd：YAG laser rod having Gaussian pump profile

In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd:YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.