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  In the other hand, shear waves have drawn an increasing interest in medical imaging, with the development of shear wave elastography techniques for the last two decades \cite{muthupillai1995magnetic}, \cite{sandrin2002shear}. As its names indicates, this term covers the techniques used to measure or map the elastic properties of biological tissues using shear wave propagation. The shear modulus, directly proportional to Young's modulus in soft tissues, varies of several orders of magnitude between different tissues in human body and potentially offers a good contrast. As a shear wave propagates in an organ at a speed proportional to the square root of the shear modulus, measuring its speed throughout the organ allows to compute the shear modulus of the tissue. Shear waves can be induced by an external vibrator \cite{muthupillai1995magnetic}, a focused acoustic beam \cite{sarvazyan1998shear}, \cite{11937286}, the Lorentz force \cite{16051039}, \cite{grasland2014elastoEMarticle}, or natural body displacements \cite{gallot2011passive}, \cite{Zorgani_2015}, \cite{Weaver_2012}. Shear wave elastography techniques have been successfully applied for the detection of various pathologies in organs such as the liver \cite{sandrin2003transient}, the breast \cite{goddi2012breast}, \cite{sinkus2005viscoelastic}, the prostate \cite{cochlin2002elastography}, \cite{12878247}, the arteries \cite{schmitt2010ultrasound} and the eye cornea \cite{tanter2009high}, to name a few examples. Very recently, Li et al. have used induce surface acoustic wave induced with a laser to assess bladder wall elasticity \cite{25574440} and cornea elasticity \cite{22627517}.  In this study, we show that shear waves can be induced in soft tissues by a laser beam. We also have been able to distinguish two different regimes depending on laser energy. We  propose a physical  model for to describe  the underlying physics. observed phenomenons.  We finally applied the technique in a biological tissue to evaluate its show the  potential application in shear wave elastography. In the first experiment, illustrated by Figure \ref{Figure1}, we used a Q-switch Nd:YAG laser (EverGreen 200, Quantel, Les Ulis, France), which produced a pulse of energy $E$ = 200 mJ at a central wavelength of 532 nm during 10 ns in a 5 mm diameter circular beam.We defined  Z is defined here  as the laser beam axis and origin of coordinates (0,0,0) as  the laser impact location on the medium as the origin of coordinates (0,0,0). medium.  The laser beam was absorbed in a 4x8x8 cm$^3$ tissue-mimicking black mat phantom made of water and of 5\% polyvinyl alcohol and 1 \% black graphite powder. A freezing/thawing cycle was applied to stiffen the material to a value of 15$\pm$5 kPa \cite{17375819}. To observe the resulting shear waves, the medium was scanned with a 5 MHz ultrasonic probe made of 128 elements connected to a Verasonics scanner (Verasonics V-1, Redmond, WA, USA). Thelaser beam was triggered 10 ms after the first ultrasound acquisition, $t$ = 0 ms being defined as the laser emission. The  probe was used in ultrafast mode \cite{bercoff2004supersonic}, acquiring 1500 4000  ultrasound images per second. second during 30 ms.  Due to the presence of graphite particles, the medium presented a speckle pattern on the ultrasound image. Tracking the speckle spots with an optical flow technique (Lucas-Kanade method) method with a 64x5 pixels window)  allowed to compute Z-axis component of the displacement in the medium. The displacements Displacements  along time were then filtered from 200 to 800 Hz using a 5th order Butterworth filter.