The properties of quadratic spatial solitons generated in periodically poled lithium tantalite in the femtosecond regime are investigated. By using only a fundamental frequency beam as the input to excite quadratic spatial solitons, single and spatially anisotropic multiple solitons are generated. Our experiments demonstrate that the number of solitons is dependent on the input power. In the experiment, beam narrowing occurs first, leading to single-soliton generation. The threshold for multiple solitons is around 1.5 mW. The number of solitons does not increase indefinitely with input power. Multiple soliton generation only occurs in the input power range of 1.5 to 6.3 mW. The number of solitons decreases to 1 when the input power is 6.3 mW. The temporal and spectral characteristics of the spatial solitons are measured by using the GRENOUILLE technique.
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