Detailed investigation of thermal effects in longitudinally diode-pumped Nd:YVO/sub 4/ lasers

Abstract

An investigation of thermal lensing effects in longitudinally diode-pumped Nd:YVO 4 lasers is made in detail both numerically and experimentally. A finite-element model is used to theoretically simulate thermal lensing in various Nd:YVO 4 crystals and pumping scenarios. The predicted values for thermally induced lens strengths are compared with experimentally observed results. We find that these two sets of results are in broad agreement, provided that the spatial profile of the pump-induced heat generation is accurately modeled. The saturation of the pump absorption is found to be of particular importance in producing an accurate prediction of the thermal lens strength, and a composite structure of the crystals is desirable to relieve the thermal lensing.Index Terms-Composite crystal, diode-pumped laser, Nd:YVO 4 , thermal effect, thermal lensing.

Transient thermal effect in the gain medium of pulsed and end-pumped laser

“…In our model, the periphery of the square Nd:YAG crystal is held at a constant temperature of 289K [4]. The transient temperature distribution in the crystal using a Cartesian coordinate system satisfies the partial differential equation [5] …”

Diode Pumped High Peak Power Quasi Q-Switched and Passively Q-Switched Nd:YVO<sub>4</sub> Lasers at 1064 nm and 532 nm using Cr:YAG and KTP crystals

“…In the absence of laser action; the thermal loading on the medium is strong because of the high heat absorption within the material. Therefore, the thermally induced focusing lens of the material is highest during non-lasing operation [16][17][18][19][20][21].…”

The thermal effect in a grazing-incidence slab laser with the novel composite cooling method

“…Crystals used in grazing-incidence lasers are also with large stimulated emission cross-section, especially for the conventional crystals such as Nd: YVO 4 and Nd: GdVO 4 , which can be operated with high efficiency (Bernard and Alcock 1993;Damzen et al 2001;Minassian et al 2003). Therefore, the ideal exponential absorption model is used in our modeling (Xiong et al 2003). The major sources of heat production are quantum defect (Koechner 1999), non-radiative transition (Fan 1993), fluorimetric quenching induced by impurity and defect (Danielmeyer et al 1973), and the Auger recombination (Musgrave et al 2001).…”

“…The absorption saturation is expected to occur with pump powers of only a few watts. The absorption coefficient can be presented as (Xiong et al 2003) α (x) = α 0 1 1…”