Don't have sufficient background, but could a chain reaction of electron-positron splitting and gamma rays radiation occur? I played with lasers, but whenever

Don't have sufficient background, but could a chain reaction of electron-positron splitting and gamma rays radiation occur? I played with lasers, but whenever I read something more in depth like this, I am awed by the nature of light and photons. I especially like the bit of diffracting the laser beam to not damage the amplifier, and then bringing it back to together again - no damaged amplifier, but a high energy beam!