Abstract: An optical waveguide is formed using a gas-enclosed vessel that has an internal space in which a polyvalent ionizable gas is enclosed, a laser beam irradiation unit, and a discharge circuit that causes a pulse current to flow in the gas-enclosed vessel at an initial current value. The pulse current is increased from the initial current value to a subsequent current value greater than the initial current value, and a polyvalent ionization channel is formed in the internal space, while increasing the pulse current, by irradiating the internal space in the plasma state with a trigger laser beam generated by the pulse laser beam irradiation device. The polyvalent ionization channel expands by an inverse pinch effect after the internal space is irradiated with the trigger laser beam due to a concentration of the pulse current in the internal space.

Abstract: An optical waveguide is formed using a gas-enclosed vessel that has an internal space in which a polyvalent ionizable gas is enclosed, a laser beam irradiation unit, and a discharge circuit that causes a pulse current to flow in the gas-enclosed vessel at an initial current value. The pulse current is increased from the initial current value to a subsequent current value greater than the initial current value, and a polyvalent ionization channel is formed in the internal space, while increasing the pulse current, by irradiating the internal space in the plasma state with a trigger laser beam generated by the pulse laser beam irradiation device. The polyvalent ionization channel expands by an inverse pinch effect after the internal space is irradiated with the trigger laser beam due to a concentration of the pulse current in the internal space.