Highly efficient generation of strong-field 0.1-THz radiation

We demonstrate the generation of single-cycle 0.1-THz radiation in a lithium niobate crystal using optical rectification and obtain THz output energy of 65 μJ with 31.6 MV/m peak field. This amounts to an optical-to-THz energy conversion efficiency of 0.3% at 85 K, which is in agreement with theory.