Method to generate terahertz radiation and terahertz radiation source

A method to generate terahertz radiation in a nonlinear optical medium, the method comprising:

• subjecting a pump beam to pulse front tilting by inducing a tilted pulse front of the pump beam as a sum of a plurality of pulse front tilts to satisfy a matching condition of vp,cs cos(γ)=vTHz,f including inducing individual ones of the plurality of pulse front tilts separately as a partial pulse front tilt of the pump beam in subsequent steps comprising at least a first step and a second step, where vp;cs is a group velocity of the pump beam, vTHz;f is a phase velocity of the THz pulse, and γ is an angle formed between the pulse front and the phase front of said pump beam,
• guiding the pump beam with tilted pulse front through imaging optics,
• coupling the pump beam with the tilted pulse front into the nonlinear optical medium through an entry surface of the nonlinear optical medium,
• performing a step of the subsequent steps of inducing the individual ones of the plurality of pulse front tilts by coupling the pump beam into the nonlinear optical medium through a stair-step structure formed in the entry surface of the nonlinear optical medium,
• generating THz radiation using the optical medium in nonlinear optical processes as a result of the pump beam, and
• passing the THz radiation through an exit surface of the nonlinear optical medium that is parallel within about two degrees to the entry surface of the nonlinear optical medium.