Ultrafast laser induced microexplosion: A new strategy to synthesise super-dense nanomaterials

The authors demonstrate the ability to compress materials to high density/temperature using femtosecond laser pulses from a standard table-top laser tightly focused inside transparent dielectrics such as glass, quartz, or sapphire. Extremely high pressure (~10 TPa) and temperature (5 times10⁵K) have been produced using a single ~200 fs laser pulse focused inside transparent dielectrics. The laser pulse of intensity over 0.1 PW/cm² converts a material within the absorption volume of ~0.15 mm³ into plasma in a few femtoseconds. A pressure of ~10 TPa, far exceeding the strength of any material, builds up to the end of the pulse. The pressure generates strong shock and rarefaction waves. Finally, this results in the formation of a nano-void surrounded by a shell of shock-compressed material. In sapphire, the size of the compressed shell revealed that it has a density 1.14 times of the initial sapphire density. The unique conditions, namely, the extreme pressure and temperature at record high heating and cooling rates become available in a well-controlled laboratory environment.