Systems and methods for spatiotemporal control of a laser and applications of same
Methods and systems are disclosed for using a chromatic lens system to provide a “flying focus”—i.e., an advanced focusing scheme enabling spatiotemporal control of a focal location. In a method, a photon beam is emitted from a source at a wavelength. The photon beam may have more than one wavelength. The photon beam is focused to a focal location using a chromatic lens system. The focal location is at a first longitudinal distance along an optical axis from the chromatic lens system. The wavelength of the photon beam is changed as a function of time to change the focal location as a function of time. The wavelength may be changed such that the focal location changes with a focal velocity.
1. A method for amplifying a photon beam, comprising:
providing a pump beam emitted from a first source into a medium in a first propagation direction, wherein the pump beam has a pump beam wavelength (λ1);
providing a seed photon beam emitted from a second source into the medium in a second propagation direction which is substantially opposite to the first propagation direction, wherein the seed photon beam has a group velocity;
focusing the pump beam to a pump beam focal location in the medium using a chromatic lens system to ionize the medium at the focal location;
changing the wavelength of the pump beam to change the pump beam focal location and inducing an ionization front with an ionization front velocity which matches the group velocity of the seed photon beam; and
wherein a difference between a frequency and wave vector of the pump beam and a frequency and wave vector of the seed photon beam is equal to a frequency and wave vector of a periodic electron density modulation.
2. The method of claim 1 , wherein the wavelength of the pump beam is changed as a function of time, and the function of time is selected such that a portion of the pump beam energy is transferred to the seed photon beam by way of the periodic electron density modulation.